Documents published in 2024 : Scipedia

Influence evaluation of flow diverter stent parent vessel coverage on cerebral aneurysm through the CFD-DEM coupling simulation
Y. Ohkura, D. Watanabe, R. Taniguchi, S. Yamani

WCCM2024.

Abstract
Cerebral aneurysms are a type of cerebrovascular disorder where a balloon-like bulge forms in part of an artery in the brain. One of the developed treatments for large cerebral aneurysms is the Flow-diverter Stent (FDS) placement technique. Effective treatment outcomes in cerebral aneurysm treatment using FDS require proper placement of the device. Improper placement can lead to increased blood flow velocity and Wall Shear Stress (WSS) within the aneurysm, as well as increased pressure, which suggests a potential risk of rupture in large aneurysms. Considering these circumstances, this study evaluates the impact of FDS positioning on cerebral aneurysms by creating multiple FDS placement models with the device positioned proximally and distally to the aneurysm. Subsequently, we conducted fluid-structure interaction simulation analyses using the Particle Finite Element Method-Second Generation (PFEM-2) for the non-Newtonian fluid model of blood and the Discrete Element Method (DEM) for the FDS. This study reports the results of comparing blood behavior, WSS, and pressure inside the cerebral aneurysm based on the FDS placement position.
Abstract
Cerebral aneurysms are a type of cerebrovascular disorder where a balloon-like bulge forms in part of an artery in the brain. One of the developed treatments for large cerebral [...]
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Delta-P1 model implementation for numerical simulation of photothermal cancer therapy in three-dimensional heterogeneous tissues
R. Gomez Araque, C. Bustamante, R. Valencia, W. Florez

WCCM2024.

Abstract
Photothermal therapy (PTT) stands as a promising avenue for cancer treatment. Metallic nanoparticles (NPs) absorb near-infrared light, inducing localized heating for tumor cell apoptosis. Predicting spatial temperature information in preclinical models is crucial due to cell death sensitivity to temperature changes. Heat transfer models, rely on the radiative transport equation (RTE), where its approximation is essential for this purpose. Existing models for the radiative transport equation, such as the Beer-Lambert law, the diffusion approximation, the discrete ordinates method, and Monte Carlo (MC) simulations, are widely used in the context of PTT. However, each of them has limitations. This study focuses on the δP1 model, wich is an extension of the diffusion approximation. Unlike standard diffusion approximation (SDA), the δP1 model treats forward and scattered light independently, preserving accuracy over a wider range of optical properties, including media with plasmonic NPs. The δP1 model equations are discretized and solved by the Finite Element Method (FEM) . Its numerical results for fluence rate in a heterogeneous geometry with nanoshells is compared to MC simulations and the standard diffusion approximation. This study validates and applies the model to the simulation of light transport in photothermal therapy in general two-dimensional geometries. Results demonstrate the δP1 shows a significant improvement over the SDA in heat transfer simulations in heterogeneous tissues geometries. This underscores its potential as a valuable tool for optimizing photothermal therapy preclinical models.
Abstract
Photothermal therapy (PTT) stands as a promising avenue for cancer treatment. Metallic nanoparticles (NPs) absorb near-infrared light, inducing localized heating for tumor [...]
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Deriving intervertebral disc FEM models from MRI image segmentation in large cohorts
K. Nispel, T. Lerchl, G. Gruber, H. Moeller

WCCM2024.

Abstract
Due to limited MRI resolution, patient-specific simulation models derived from medical images often lack bio-fidelity. To address this, we present a smoothing pipeline for generating high-fidelity meshes of vertebrae and intervertebral discs from medical images, which serve as a base for biomechanical simulations. Using a diverse array of vertebrae smoothing algorithms, including Laplace, HC Laplace, Taubin, and Two Step, alongside surface subdivision methods such as Tri-to-Quad by 4-8, Loop, LS3-Loop, Catmull-Clark, and Butterfly, we systematically explored 136 combinations across six protocols to determine an optimal smoothing pipeline. Subsequently, an adaptive smoothing algorithm was developed for intervertebral disc meshes. By adjusting intervertebral disc vertex locations to those of the vertebra mesh, we ensured seamless alignment of contact surfaces including shared nodes. Evaluation of our pipeline against conventional smoothing methods demonstrates superior edge preservation and reduced stair-step effects, enhancing the fidelity of the generated meshes. Finite Element Method simulations further confirmed the accuracy of our selective smoothing pipeline, showing increased notch stress. Our pipeline, validated on a diverse dataset, offers an automated solution for generating patient-specific vertebrae and intervertebral disc models with enhanced biomechanical fidelity, enabling comprehensive studies in large cohorts and deeper insights into spine biomechanics and pathology.
Abstract
Due to limited MRI resolution, patient-specific simulation models derived from medical images often lack bio-fidelity. To address this, we present a smoothing pipeline for [...]
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Optimum design method for artificial ear ossicles based on a high-precision vibration analysis model
Y. Liu

WCCM2024.

Abstract
In this study, we propose a topology optimization approach aimed at designing an optimal artificial auditory ossicle to enhance hearing restoration in the sound conduction reconstruction of a damaged human middle ear. The primary objective of our design is to maximize the vibration displacement of the stapes footplate by employing the concept of mutual mean compliance. Using this method, we can determine the optimal topology configurations of the artificial component based on topology sensitivity, which we theoretically derive in this paper. To demonstrate the effectiveness and practical utility of our proposed approach, we present a design example of artificial auditory ossicles utilized in tympanoplasty procedures.
Abstract
In this study, we propose a topology optimization approach aimed at designing an optimal artificial auditory ossicle to enhance hearing restoration in the sound conduction [...]
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Markov chain Monte Carlo capabilities in Dakota
E. Prudencio, A. Stephens

WCCM2024.

Abstract
We give an overview of MCMC capabilities in the Dakota software package from Sandia National Laboratories, and present some Bayesian calibration results.
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Modelling and simulation of a fully electric hybrid propulsion system for passenger ships using AVL Cruise-M software
L. Micoli, R. Russo, T. Coppola, D. Severi

WCCM2024.

Abstract
The maritime industry's pursuit of sustainability drives the exploration of alternative fuels, with hydrogen emerging as a promising solution. This paper presents a comprehensive study on a fully electric hybrid propulsion system for passenger ships, utilizing hydrogen as the primary power source. Multi-physics simulation using AVL Cruise-M software enables detailed analysis of system dynamics and performance. Results from a full acceleration test reveal the intricate interplay between the fuel cell and battery system, crucial for meeting power demands during transient phases. Examination of material flows highlights the importance of maintaining optimal water balance for system efficiency and durability. Temperature and pressure variations significantly influence FC efficiency, showcasing improvements over time, stabilizing at approximately 56% efficiency after 2.6 minutes. These findings underscore the value of comprehensive simulations and temporal analysis in optimizing hybrid propulsion systems, suggesting strategies for further enhancement, such as precise temperature and mass flow control.
Abstract
The maritime industry's pursuit of sustainability drives the exploration of alternative fuels, with hydrogen emerging as a promising solution. This paper presents a comprehensive [...]
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Understanding the solidification and heat treatment characteristics in the CoCrNiSix medium-entropy alloy by experimentally verifiable multiscale thermodynamic and kinetic computational techniques
T. Su, H. Huang, J. Chen

WCCM2024.

Abstract
CoCrNi medium-entropy alloy (MEA) possesses an FCC crystal structure with multiple slip systems and low stacking fault energy [1]; a substantial amount of nanoscale deformation twins can be generated under low-temperature and high-speed deformation. Adding a proper amount of Si can not only reduce the manufacturing cost and mass density but also enhance ballistic resistance by further lowering the stacking fault energy. Previous studies [2] utilized small-scale vacuum arc remelting techniques to investigate the solid solution or secondary phase strengthening of CoCrNi-based MEAs with Al or Si additions. However, to extend the application of lightweight, high-entropy alloys to industrial-grade impact-resistant plate manufacturing, especially for low-temperature environments, it is necessary to study the solidification and heat treatment characteristics of CoCrNiSix castings. This study employs finite element analysis at the macroscopic scale to investigate the solidification phase transformation and heat transfer characteristics of CoCrNiSix under precision-cast conditions. Additionally, at the mesoscopic scale, the phase-field method [3] is used to simulate the dendritic solidification microstructure and element segregation of CoCrNiSix. Thermodynamic parameters required for simulations are calculated using Thermo-Calc high-entropy alloy databases TCHEA6 and MOBHEA2. This research also utilizes electron microscopy to analyze the microstructures of chemically complex CoCrNiSix ingots, focusing on measuring the secondary dendrite arm spacing and elemental segregation profiles. Collecting these microstructure-related features allows us to reasonably infer the cooling rate corresponding to the investment casting process of CoCrNiSix and design rational parameter combinations for homogenization heat treatment of the cast ingots in terms of temperature and isothermal holding time. By validating macroscopic and mesoscopic simulation results through CoCrNiSix microstructure analysis experiments, the multiscale kinetic computational techniques included in this study can be further applied to cost-saving and process optimization practices in the manufacturing of various lightweight high-entropy alloys
Abstract
CoCrNi medium-entropy alloy (MEA) possesses an FCC crystal structure with multiple slip systems and low stacking fault energy [1]; a substantial amount of nanoscale deformation [...]
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Space-time Galerkin finite element discretization and error control for coupled problems
T. Wick, P. Junker, J. Thiele, J. Roth

WCCM2024.

Abstract
In this work, we consider one key component, namely the wave equation, of a recently proposed space-time variational material model. The overall model is derived from a thermodynamically consistent Hamilton functional in the space-time cylinder in which mechanics, temperature and internal variables couple. Through the derivation, rather unusual end time conditions for the second-order in time wave equation arise. In order to understand their behavior better, we solely focus on the wave equation (neglecting temperature and internal variables) and formulate a Galerkin finite element discretization in time and space. Based on this discretization and the corresponding implementation, some numerical simulations are conducted. Therein, both traditional initial conditions for the displacements and the velocities are considered, as well as our newly proposed conditions for initial time and final time acting on the velocity variable only
Abstract
In this work, we consider one key component, namely the wave equation, of a recently proposed space-time variational material model. The overall model is derived from a thermodynamically [...]
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Goal oriented error estimation for space-time adaptivity in phase-field fracture
V. Kosin, A. Fau, F. Hild, T. Wick

WCCM2024.

Abstract
This work focuses on temporal adaptivity for phase-field fracture problems. The methodology requires a space-time formulation and utilizes a space-time Galerkin finite element discretization for the governing phase-field equations. Then, goal functionals (i.e., quantities of interest) are introduced. The computational implementation of goal-oriented error control employs the dual-weighted residual method in which an adjoint problem must be solved. As the analysis is quasi-static, without a temporal derivative, the adjoint problem of the quasistatic primal problem decouples in time. Nonetheless, time-averaged goal functionals can also be considered. The temporal errors are localized using a partition of unity, which allows one to adaptively refine and coarsen the time intervals in the space-time cylinder. Numerical tests are performed on a single edge notched tensile test to investigate the quality of the proposed error estimator.
Abstract
This work focuses on temporal adaptivity for phase-field fracture problems. The methodology requires a space-time formulation and utilizes a space-time Galerkin finite element [...]
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Assessment of flow-induced stresses in spiral weld pipes with bends
S. Ahmadizade, S. Verma, A. Hemmati

WCCM2024.

Abstract
This study numerically investigates flow-induced stresses and displacements in bent pipes at varying angles (20◦ ≤ θb ≤ 80◦ ) using Solids4Foam at Reynolds number of 20,000. The results indicate that increasing θb enhances the formation of symmetric vortex structures, which coincide with enhanced non-uniformity in pressure distribution and wall shear stresses. Additionally, maximum equivalent stresses (σeq) for the solid shell occur near the inlet. The pipes with higher θb also depict a reduced displacement magnitude(D), which hints at the strong role of fixed displacement boundary condition assigned at the pipe inlet and outlet. These findings provide essential insights for performing numerical investigation of pipeline reliability and structural integrity in oil transportation.
Abstract
This study numerically investigates flow-induced stresses and displacements in bent pipes at varying angles (20◦ ≤ θb ≤ 80◦ ) using Solids4Foam at Reynolds number [...]
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Computational interpretation of shape memory epoxy: processing and its operation
Y. Kim, H. Kim, J. Choi

WCCM2024.

Abstract
The shape forming and restoration mechanisms of shape memory epoxy originate from the molecular-scale dynamics that epoxy molecules undergo during thermomechanical processes. In this study, the microstructural changes that occur at the molecular scale caused by heat and load during the programming and operation of the epoxy network were investigated using molecular dynamics simulations. The mechanical behaviors of each molecule were analyzed by classifying it into translation, rotation, and deformation based on the classical kinematic framework. Specifically, depending on its structural properties, each molecular component was rearranged to different levels, forming local residual stresses. The principle leading to shape recovery as the subsequent thermal load breaks the equilibrium of residual stresses and resulting changes in the mechanical anisotropy of entire epoxy network were also analyzed through a subcontinuum perspective. This study has the potential to be extended to a method for designing epoxy resins that satisfy desired physical properties and shape recovery performance
Abstract
The shape forming and restoration mechanisms of shape memory epoxy originate from the molecular-scale dynamics that epoxy molecules undergo during thermomechanical processes. [...]
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An improved flux vector splitting method for characteristic-wise WENO schemes of the Euler equations
J. Kim, Y. Shen

WCCM2024.

Abstract
Steger-Warming (SW) [1] and Lax-Friedrich-type (LF) [2] flux vector splitting methods are used extensively by shock capturing WENO schemes in varieties of compressible flow simulations. Due to the less dissipation, the SW method is preferred in flow calculations that require fine scale structures such as direct numerical simulation of turbulence. However, this paper shows that, even if the characteristic-wise WENO scheme is used, the SW method may still exhibit some oscillations near contact discontinuities, while the LF method does not. Analysis similar to the reference [3] shows that, using the SW method may make the characteristic-wise WENO scheme become close the component-wise WENO scheme near subsonic contact discontinuities. Based on that, an improved flux vector splitting method, which adjusts the eigenvalues of the flux vector splitting in the characteristic-wise WENO procedure, is proposed to obtain the low-dissipation property and prevent contact discontinuity oscillations at the same time. Numerical experiments are performed to validate and evaluate the new method. Numerical results show that the proposed method keeps the non-oscillatory flow field near discontinuities as LF method and also avoids smearing out other flow regions, similar to the SW method.
Abstract
Steger-Warming (SW) [1] and Lax-Friedrich-type (LF) [2] flux vector splitting methods are used extensively by shock capturing WENO schemes in varieties of compressible flow [...]
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Modeling the enhanced geothermal systems using the extended–FEM and an equivalent continuum model
A. Khoei, S. Mortazavi, O. Rezaie Beydokhti, P. Pirmoradi

WCCM2024.

Abstract
. In this paper, a computational technique is presented for Thermo-Hydro-Mechanical (THM) simulation of Enhanced Geothermal Systems (EGS) based on the eXtended Finite Element Method (XFEM) and Equivalent Continuum Method (ECM) in the framework of Local Thermal Non-Equilibrium (LTNE). Heat extraction from Enhanced Geothermal Systems involves several multi-physics coupling processes, including the seepage through the fractured porous media, the thermal exchange between the working fluid and the matrix, and the deformation of fractured porous media that play essential roles in exploiting the geothermal energy contained in hot dry rocks. The ECM provides the equivalent tensors for the fluid permeability and solid compliance, which is an essential feature for the coupled Thermo-Hydro Mechanical simulation of fracture networks. In the model, the XFEM is employed for large scale fractures to capture the mass and heat transfer between the fracture and matrix more accurately, while the ECM is applied on the network of small-scale fractures. Hence, the proposed model benefits from the advantages of both methods, and it allows for managing between accuracy and cost. The set of THM equations is solved with both Local Thermal Equilibrium (LTE) and Local Thermal Non-Equilibrium (LTNE) assumptions to find out the impact of each method on the production temperature. The capability of the proposed computational model is demonstrated for the diagonal arrangement of the injection and production wells with different fracture orientations in-between. The simultaneous effects of fracture connectivity and inclination are investigated between the two injection and production wells. It is observed that the temperature difference between the two cases is higher in the middle of the domain by comparing the results of LTE and LTNE assumptions. Moreover, it is concluded that the LTE model overestimates the fluid temperature in comparison to the LTNE model in cold water injection problems. The results show the proposed computational model is a promising tool for estimation of the heat mining performance of EGS
Abstract
. In this paper, a computational technique is presented for Thermo-Hydro-Mechanical (THM) simulation of Enhanced Geothermal Systems (EGS) based on the eXtended Finite Element [...]
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Stabilization of mixed displacement-pressure finite elements at finite strains using polyhedral formulations and Voronoi meshing
B. Sauren, E. Oheim, S. Klinkel

WCCM2024.

Abstract
The hexahedral mixed displacement-pressure finite element of the lowest order (H1/P0) has shown to be simple and effective during both linear and nonlinear analysis of incompressible solids. While the discrete displacement field is generally considered to be sufficiently accurate, the discrete pressure field can sometimes be heavily polluted by spurious pressure modes. This results from the fact that the element does not fulfill the inf-sup condition. While postprocessing techniques, such as pressure filtering or smoothing, exist to remove the spurious pressure modes from the solution, this contribution aims on the exclusion of spurious pressure modes from the solution a priori due to the element geometry. By employing polyhedral finite element formulations on Voronoi tessellations in three dimensions, we show that the discrete kernel of the linearized mixed bilinear form only consists of the hydrostatic pressure mode. A spurious pressure mode is automatically suppressed due to the vertex-to-volume ratio in the finite element mesh. These considerations hold for any arbitrary physically admissible displacement state that can occur within a Newton-Raphson framework. A nonlinear numerical example shows that spurious pressure modes are indeed suppressed if the type of tessellation is changed from hexahedral to Voronoi.
Abstract
The hexahedral mixed displacement-pressure finite element of the lowest order (H1/P0) has shown to be simple and effective during both linear and nonlinear analysis of incompressible [...]
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A coupled SPH-FDM method for simulations of unsteady flows
C. Huang, H. Jiang, F. He, A. Shakibaeinia

WCCM2024.

Abstract
The fluid-flexible-structure interaction (FFSI) is characterized by the large deformation, the thin structure, and the complex of the flow field. Accurately simulating FFSI poses three challenges, which are the reproduction of thin structure, the capture of moving interface, and the numerical stability of multi-physics field coupling, respectively. In this study, the FFSI is simulated by the smoothed particle hydrodynamics (SPH) because of its natural advantage in dealing with the moving interface. The shell model with single-layer particles[1] is introduced into SPH to simulate the thin flexible structure. The truncation error caused by the single-layer boundary is modified by the normal flux approach[2]. κ-ε turbulence model is introduced into SPH to enhance the numerical stability and capture complex flow details. In addition, other techniques or models that ensure the efficiency and stability of the calculation are used in this study, including PST (particle shifting technique), δ-SPH method, and GPU (graphics processing unit). The flows around the single filament are simulated to verify the accuracy and stability of the current FFSI algorithm based on the SPH method.
Abstract
The fluid-flexible-structure interaction (FFSI) is characterized by the large deformation, the thin structure, and the complex of the flow field. Accurately simulating FFSI [...]
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A computationally efficient method for considering a large number of nonlinear multi-point constraints within the finite element method
J. Wackerfuβ, J. Boungard

WCCM2024.

Abstract
Nonlinear constraints are crucial in modeling various problems in computational mechanics. Among other things, they can be used for the subsequent consideration of rigid inclusions in a body originally modeled as deformable, without requiring a remeshing of the considered domain and thus contributing to a rapid modeling building. Unlike Lagrange multipliers and the penalty method, the master-slave elimination reduces the problem dimension but is limited to linear constraints. We introduce a new master-slave elimination method for arbitrary nonlinear multi-point constraints. It is compared to existing methods through analysis of the resulting equations and numerical examples. Results indicate that the method is as accurate, robust, and flexible as Lagrange multipliers, with improved efficiency due to reduced degrees of freedom, which is particularly advantageous when a large number of constraints have to be considered.
Abstract
Nonlinear constraints are crucial in modeling various problems in computational mechanics. Among other things, they can be used for the subsequent consideration of rigid inclusions [...]
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Geometric formulation of three-temperature radiation hydrodynamics
B. Tran, B. Southworth, J. Burby, M. Leok

WCCM2024.

Abstract
Three-temperature (3T) radiation hydrodynamics models high energy-density plasma of nonlinearly coupled electron, ion, and radiation fields, finding applications in astrophysics and inertial confinement fusion. We present a geometric formulation of three-temperature radiation hydrodynamics. This is done utilizing an irreverisble portHamiltonian framework in the entropy representation. This geometric formulation separates the advection, interaction, and diffusion processes occuring into separate operators and establishes the energy-preserving interconnections between them. Structural properties such as mass, momentum and energy conservation as well as entropy production arise naturally from the geometric formulation. As an application, we briefly discuss a framework for the energy control of the 3T system within the port-Hamiltonian framework.
Abstract
Three-temperature (3T) radiation hydrodynamics models high energy-density plasma of nonlinearly coupled electron, ion, and radiation fields, finding applications in astrophysics [...]
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The Picard-Newton iteration for the Boussinesq equations
L. Rebholz, E. Hawkins

WCCM2024.

Abstract
We consider the Picard-Newton and Anderson accelerated Picard-Newton solvers applied to the Boussinesq equations, nonlinear Helmholtz equations and Liouville equation, for the purpose of accelerating convergence and improving robustness with respect to problem parameters. In all cases, we show the proposed solvers improve efficiency over the commonly used solvers and are able to find solutions for a much larger set of problem parameters.
Abstract
We consider the Picard-Newton and Anderson accelerated Picard-Newton solvers applied to the Boussinesq equations, nonlinear Helmholtz equations and Liouville equation, for [...]
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A new concept for embedding sub-structures via level-sets
T. Fries, J. Neumeyer, M. Kaiser

WCCM2024.

Abstract
A framework is presented to continuously embed sub-structures such as fibres and membranes into otherwise homogeneous, isotropic bulk materials. The bulk material is modeled with classical finite strain theory. The sub-structures are geometrically defined via all level sets of a scalar function over the bulk domain. A mechanical model that is simultaneously applicable to all level sets is given and coupled to the bulk material. This results in a new concept for anisotropic materials with possible applications in biological tissues, layered rocks, composites, and textiles. For the numerical analysis, the bulk domain is discretized possibly using higher-order finite elements which do not conform to the level sets implying the shapes of the embedded sub-structures. Numerical results confirm the success of the proposed embedded sub-structure models in different contexts
Abstract
A framework is presented to continuously embed sub-structures such as fibres and membranes into otherwise homogeneous, isotropic bulk materials. The bulk material is modeled [...]
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On triangular self-stabilized virtual elements for Kirchhoff-Love shells
T. Park Wu, P. de Mattos Pimenta, P. Wriggers

WCCM2024.

Abstract
This work presents a self-stabilized triangular virtual element for linear Kirchhoff–Love shells. The domain decomposition by flat triangles directly approximates the shell geometry without resorting to a curvilinear coordinate system or an initial mapping approach. The problem is discretized by the lowest-order conventional virtual element method for the membrane, in which stabilization is needless, and by a stabilization-free virtual element procedure for the plate. Numerical examples of static problems show the potential of the formulation as a prelude for the evolution of self-stabilized Kirchhoff–Love shell virtual elements.
Abstract
This work presents a self-stabilized triangular virtual element for linear Kirchhoff–Love shells. The domain decomposition by flat triangles directly approximates the shell [...]
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Projector assembly: bridging Poisson and elasticity formulations
T. Moherdaui, A. Gay Neto, P. Wriggers

WCCM2024.

Abstract
Virtual element methods define their shape functions implicitly (tailored to each element’s geometry), foregoing the typical reference element and transformation scheme usually employed by the finite element method. The formulation leverages the use of polynomial projections supplied by heuristic stabilizations when necessary. These projections are represented by projector matrices, which require the solution of a local system. Elasticity formulations usually employ an ð¿ 2 -projection from a displacement multifield onto a strain multifield, requiring the solution of a considerably larger system than a typical Poisson problem would require, with dense matrices and lots of zeroes. This work presents a way to obtain the projections for elasticity formulation by assembling from the ð¿ 2 -projection for each derivative of the one-field a Poisson formulation, resulting in smaller local systems being solved and more efficient storage. This approach is based on the linearity of both projections and derivatives, and is shown in the examples to preserve the convergence rate of the method.
Abstract
Virtual element methods define their shape functions implicitly (tailored to each element’s geometry), foregoing the typical reference element and transformation scheme [...]
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Mixed partition of unity methods and stochastic Gillespie algorithms for Transport-Reaction equations
M. Kirkilionis

WCCM2024.

Abstract
We introduce a new type of model framework which is part stochastic and part deterministic. The starting point is a finite size particle system within a single reaction volume, with type exchanges modelled by a contact process. Inside the reaction volume, each particle can interact with every other particle with the same probability. This is the setting of a classical reaction system simulated with a Gillespie algorithm. Such systems can be used to describe other than chemistry type exchanges, like an infection process, and therefore are already very versatile. Their advantage is that they are able to be used where small size effects can play a role, like extinction events, which are impossible to model with differential equations, including stochastic differential equations. However finite size and single reaction volume settings for reaction systems are too restrictive in other ways. We might like to add internal or external states to the particles. These states are coordinates in a position space. An example of an internal position/state space is age (since entering the system), an example for an external position/state space is geographical location. The particles then can also change their positions in these state spaces, according to some probability distribution which evolution is modelled deterministically. The classical example for a transport process is a partial differential equation like the heat equation, or more general parabolic advection-diffusion equations. We assume that the distribution of the particles in position space is not influencing the evolution of the probability distribution driving in turn the evolution of the particles’ positions. The model framework with its finite-size particle population approach can very accurately model situations where finite-size effects take place, however provides in addition detailed descriptions of both internal and external particle state spaces where needed. The framework can therefore be used in addition to traditional established models, like transport PDEs or internally structured population models, when the computation of the statistics of finite-size effects is important.
Abstract
We introduce a new type of model framework which is part stochastic and part deterministic. The starting point is a finite size particle system within a single reaction volume, [...]
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Immersed-boundary approach based on integrated RBFs and smooth extension for solving PDEs in complex domains
N. Mai-Duy, C. Tran, D. Strunin, W. Karunasena

WCCM2024.

Abstract
We propose an immersed-boundary approach, based on point collocation, five-point integrated radial basis function stencils, rectangular Cartesian grids and smooth extension of the solution, for solving the two-dimensional elliptic partial differential equation in a geometrically complex domain.
Abstract
We propose an immersed-boundary approach, based on point collocation, five-point integrated radial basis function stencils, rectangular Cartesian grids and smooth extension [...]
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pyMesoscale: A friendly python library for generating 3D concrete mesoscale models based on the local background grid method
F. Muhammad, S. Kolawale Adekunle

WCCM2024.

Abstract
Mesoscale modeling of concrete and its composites has attracted a lot of researchers over the years with the promise of establishing an accurate relationship between the mesoscopic model and the macroscopic mechanical properties of concrete. The primary constraints inhibiting the widespread application of mesoscale modeling include (i) achieving high packing density with control over aggregate shape and gradation, (ii) high computational cost, (iii) accomplishing realistic interfacial transition zone, and (iv) implementing efficient aggregate intrusion detection. Besides these constraints, one major challenge is the lack of open program codes for algorithms implemented in published research papers. For example, improving, upgrading, and repurposing an existing algorithm by other researchers requires the open availability of the codes. The unavailability of these codes and the common absence of subtle implementation details in published papers hinder research progress on mesoscale modeling of concrete composites. This paper presents pyMesoscale, a Python library for generating 3D mesoscale models for concrete like composites. pyMesoscale implements the local background method, a highly effective mesoscale generation algorithm that offers a much better aggregate intrusion detection system and a high aggregate volume fraction. Developed with Python due to its smoother learning curve and beginner friendliness, pyMesoscale reduces implementation complexity for ease of use by both new and experienced researchers in the field. This paper offers the mathematical formulars and the detailed steps required to implement the generation of mesoscale geometric model of concrete and its derived mesoscale finite element model covering aggregate gradation and shape, random aggregate translation and aggregate intrusion detection.
Abstract
Mesoscale modeling of concrete and its composites has attracted a lot of researchers over the years with the promise of establishing an accurate relationship between the mesoscopic [...]
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Modeling the quasi-brittle fracture of structural materials using a mixed stabilized two-field finite element formulation
C. Guzmán, W. Morocho, S. Cáceres, E. Castillo

WCCM2024.

Abstract
The fracture process zone (FPZ) is typically characterized as a small region around a crack where non-linear phenomena occur, such as plasticity. In brittle materials, this zone is small and can be safely neglected. However, in quasi-brittle materials, which exhibit a combination of brittle and ductile behavior rather than a clear manifestation of either, the material within the FPZ tends to damage and displays a softening curve after reaching peak load. This behavior is frequently observed in structural materials like concrete and timber, and it can be challenging to model. Traditionally, displacement-based irreducible finite element (FE) formulations have been widely used for simulating structural materials. However, this approach comes with significant drawbacks, such as mesh dependence and convergence problems, when applied to certain phenomena like softening, localization, and fracture. To address these challenges, various techniques have been employed, including extended FE methods and phase-field modeling. In this work, the utilization of a mixed FE formulation in which both displacement and strain serve as primary unknowns within the system, is proposed. To ensure satisfaction of the inf-sup condition, which is associated with saddle point stability in mixed formulations, we employ the variational multiscale method to introduce stabilizing terms into the system. The implementation is conducted using FEniCS, an open-source FE software that offers a high-level programming interface written in Python. The implementation is validated by comparing the obtained results with those reported in the literature for bending test in notched specimens. The results demonstrate remarkably good performance in terms of maximum load, softening curve, and structural size effect in various specimens, exhibiting minimal mesh dependence even when using low-order interpolation elements
Abstract
The fracture process zone (FPZ) is typically characterized as a small region around a crack where non-linear phenomena occur, such as plasticity. In brittle materials, this [...]
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Calibration of damage parameters of super high-rise frame-core structural subsystem under torsional ground motion
Z. Guo, Y. Ma, Z. He

WCCM2024.

Abstract
To clarify the dynamic characteristics of the structure under torsional seismic excitation, a macroscopic dynamic model of the structure and simplified hysteretic models of each sub-system were established through theoretical derivation, and the accuracy of the models was verified using finite element models. To determine the design parameters of the hysteretic models for each sub-system, a multi-objective seismic optimization approach considering both structural cost and overall torsional damage was proposed. Through multi-objective optimization based on torsional overturning analysis, the design parameters of each sub-system were successfully determined. The results indicate that the outrigger truss sub-system plays a significant role in controlling the overall torsional behavior of the structure.
Abstract
To clarify the dynamic characteristics of the structure under torsional seismic excitation, a macroscopic dynamic model of the structure and simplified hysteretic models of [...]
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Synergistic effects of environmental deterioration on fatigue and flexure properties of glass fiber reinforced polymeric (GFRP) composites : a multiscale and multiphysics model.
Z. Li, M. Lepech

WCCM2024.

Abstract
This study aims to simulate synergistic UV & moisture deterioration and demonstrate its role in changing the residual fatigue and flexure strength in architectural GFRP composite material. This study develops an experimentally validated 3D Multiphysics model at a structural level and gets this homogenization-based model to identify the degradation mechanisms observed in the experimental data. Sensitivity analyses are conducted to investigate the effect of mesh density on the accuracy of functions homogenized from micromechanical models. In addition, this macroscale model also quantifies how these degradation mechanisms weaken the strength and durability of environmentally aged composite materials. The aging-fatigue-bend macroscale model assumes that the degradation-induced damage field is concentrated within a depth to the plate surface. According to the computational results, the degradation process caused by the combined effect of UV and moisture exposure involves the removal of polymeric matter from the exposed surface. In other words, the degradation mechanism of UV exposure involves both the chemical alteration and mechanical damage of polymeric matter, primarily located at the exposed surface. This model can be incorporated into many commercial finite element codes for a sustainability study of composite structures/systems. In future work, the models developed in this study will be combined with life cycle assessment (LCA) tools to support better sustainability-focused new material design, thus reducing costs and environmental impacts in the built environment.
Abstract
This study aims to simulate synergistic UV & moisture deterioration and demonstrate its role in changing the residual fatigue and flexure strength in architectural GFRP composite [...]
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Conservation properties of embedded finite-element methods for flow in fractured porous media
M. Nestola, P. Zulian, M. Favino, R. Krause

WCCM2024.

Abstract
We present a simple finite element framework which enables numerical simulations of transport problems in fractured porous media based on equi-dimensional models, i.e., models where fractures are considered heterogeneities of the same geometrical dimension as the embedding background. The two main ingredients of the proposed framework are an adaptive mesh refinement strategy, and an algebraic flux correction stabilization. The proposed finite-element method for equi-dimensional models is inherently simple and can be easily implemented in any common simulation software, as it does not require the complicated management of different meshes and discretizations, which are necessary for numerical simulations based on hybrid-dimensional models, i.e., models where fractures are considered as heterogeneities of a lower geometrical dimension than the embedding background. Actually, our equi-dimensional approach provides a strategy to validate hybrid-dimensional models. Our adaptive approach is inherently conservative and naturally reduces the discretization error which, for problems with heterogeneities, is concentrated at the interfaces.
Abstract
We present a simple finite element framework which enables numerical simulations of transport problems in fractured porous media based on equi-dimensional models, i.e., models [...]
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Computational modeling of cutting disc-rock interaction in mixed ground conditions
S. Butt, G. Meschke

WCCM2024.

Abstract
This paper presents the performance of a simulation tool based on state-based peridynamic theory, developed to model the interaction between cutting discs of a Tunnel Boring Machine (TBM) and the ground being excavated. Compared to existing TBM performance prediction models, the current computational approach accounts for mixed ground conditions, different TBM and disc designs, as well as the direct coupling with wear models. The developed peridynamic model is thoroughly validated using several benchmarks, including indentation tests on sandstone specimens. Additionally, a full-scale Linear Cutting Machine (LCM) test conducted on Colorado Red granite is simulated, where cutting forces obtained from the computational model at various disc spacings are compared against experimental data. Excavation in mixed ground conditions, which can lead to excessive tool wear or failure due to rapidly changing cutting forces, was examined through an LCM experiment. Scaled-down peridynamic simulations show cutting force trends consistent with the LCM experiment results. Finally, to predict the influence of these varying cutting forces on tool life, an abrasive wear model is implemented in the peridynamic simulation framework.
Abstract
This paper presents the performance of a simulation tool based on state-based peridynamic theory, developed to model the interaction between cutting discs of a Tunnel Boring [...]
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An improved hybrid computational mechanics framework for composite damage modelling and simulation
H. Liu, G. Qi, I. Kim, D. Wowk

WCCM2024.

Abstract
In this study, an integrated modeling framework is proposed, combining continuum damage modeling (CDM), the extended finite element method (X-FEM), and the cohesive zone modeling (CZM) techniques, to model the progressive failure of fibre-reinforced composite laminates. This modeling framework has the capability to efficiently capture fibre failure, matrix cracking, and interlaminar delamination. The Schapery theory (to address polymer matrix viscoelastic behavior) is also incorporated to accurately simulate the pre-peak nonlinearity of the load-bearing response due to matrix microcracking. The proposed hybrid model is developed and implemented using Abaqus with user-defined subroutines. A multidirectional composite laminate with an open-hole notch configuration under tension (OHT) is examined as a case study. The simulation results are compared with the physical experiments in the open literature. The proposed framework represents a practical paradigm, which not only drastically reduces the pre-processing workload to build a physics-based highfidelity damage model, but also largely decreases the computational cost
Abstract
In this study, an integrated modeling framework is proposed, combining continuum damage modeling (CDM), the extended finite element method (X-FEM), and the cohesive zone modeling [...]
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Multiscale modeling of hydrogen transport in steels and its resulting embrittlement effect
X. Gao, G. Rao, C. Huang

WCCM2024.

Abstract
A multiscale modeling approach is adopted in this study to understand the hydrogen embrittlement (HE) mechanisms and to predict failure of engineering components under the influence of hydrogen environment. Molecular dynamics simulations of the bodycentered cubic (BCC) iron are conducted to examine the theories of hydrogen enhanced localized plasticity (HELP) and hydrogen enhanced decohesion (HEDE). It is shown that hydrogen aggregation at the crack tip and along grain boundary (GB) reduces the surface energy for creating new crack surfaces, leading to changes in fracture modes caused by preemptive crack propagation. At the continuum level, a numerical framework is developed, which incorporates hydrogen transport in steels and the resulting HELP and HEDE mechanisms into a finite element phase field model to predict crack initiation and propagation in engineering components. As an example, a compact tension (CT) specimen made of a pipeline steel is analyzed. The numerical model captures the phenomenon of hydrogen aggregation occurring proximal to the crack tip driven by the high gradient of hydrostatic stress and large plastic deformation in this region. The resultant hydrogen concentration elicits an interplay of HELP and HEDE effects and reduces the specimen’s load carrying capacity. With properly chosen model parameters, the numerical model has the potential of serving as tool for predicting crack propagation and ductile to brittle transition due to the presence of hydrogen.
Abstract
A multiscale modeling approach is adopted in this study to understand the hydrogen embrittlement (HE) mechanisms and to predict failure of engineering components under the [...]
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Critical planes analysis of the impact of porosities on the fatigue of metal solids
F. Fauvin, E. Feulvarch, G. Debono

WCCM2024.

Abstract
In this work, we take interest in the impact of defects present in metal solids manufactured by material fusion or by additive manufacturing on their fatigue life during cyclic loading. Indeed, we observe a more or less strong local plasticity around the defects even if the stresses remain below the elastic limit, which can strongly impact the fatigue life of such solids. In the case of a part obtained by steel casting, it is the retassures that make the part most vulnerable. In the case of solids obtained by additive manufacturing, the most damaging defects are surface roughness and porosities linked to a lack of fusion. In order to estimate the fatigue life of such solids, it is necessary to observe the states of stress and strain around the defects during a cycle. As stress levels can be relatively high locally, critical plane type criteria are relevant for estimating the fatigue life of such solids. In order to carry out a fatigue analysis of a part obtained by steel casting or by additive manufacturing, we propose to model it by finite elements, with a refinement of the elements around the porosities, then to calculate the local stress and strain states, and finally to implement a critical plane type criterion, like the Fatemi-Socie criterion. The critical planes are the planes on which the maximal shear strain amplitudes occur. The local stress and strain states can be highly multi-axial. So the determination of the critical planes can be very computationally and storage consuming. In the present work, an analysis in the space of deviators of the deformation tensor makes possible determination of such planes in each of the numerous nodes of the mesh. These three steps of calculation, correlated with experimental tests, makes it possible to envisage obtaining fatigue life laws for numerous metallic materials presenting defects.
Abstract
In this work, we take interest in the impact of defects present in metal solids manufactured by material fusion or by additive manufacturing on their fatigue life during cyclic [...]
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Semi-analytical failure prediction of adhesive joints by Finite Fracture Mechanics
T. Methfessel, C. El Yaakoubi-Mesbah, W. Becker

WCCM2024.

Abstract
The current contribution suggests a semi-analytical structural model for an adhesive joint with a closed-form higher-order description of the adhesive layer and the potential occurrence of a debonding crack. This enables a highly efficient failure prediction by the concept of Finite Fracture Mechanics, employing a coupled failure criterion that consists of a stress and an energy subcriterion. The comparison with accompanying finite element calculations and experimental findings demonstrates the high predictive quality of this approach
Abstract
The current contribution suggests a semi-analytical structural model for an adhesive joint with a closed-form higher-order description of the adhesive layer and the potential [...]
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Fatigue crack propagation behavior analysis of 15MnTi steel based on cyclic cohesion model
J. Guo, J. He, X. Sun

WCCM2024.

Abstract
15MnTi steel is widely used in high load structures such as bridges, pressure vessels, ships, and vehicles due to its excellent mechanical properties. In the course of service, the failure of steel structure is mostly caused by fatigue fracture. In order to investigate the crack growth of 15MnTi steel under fatigue load, the cohesive zone model (CZM) was used to simulate the crack growth. The CZM can simulate brittle and plastic fracture behavior by using the function of crack interface opening force and opening displacement to avoid the stress singularity of crack tip. On this basis, a cyclic cohesive zone model (CCZM) was established to study the fatigue crack propagation behavior. This model effectively links damage, tractive force, and cumulative displacement while incorporating the process of fatigue crack growth to accurately simulate material damage evolution under fatigue load. Experimental studies on crack growth in 15MnTi steel at three stress ratios reveal a linear relationship between crack growth rate and stress intensity factor range for different stress ratios. The parameters of Paris formula were calculated using crack growth rate and stress intensity factor range, which provided reference for the selection of model parameters. By utilizing the user element subroutine (UEL) in Abaqus and compiling the CCZM using Fortran language specifically for 15MnTi steel, simulations were conducted to analyze the evolution of crack tip state under various stress ratios and discuss the corresponding crack growth behavior based on experimental observations. The results demonstrate that the fatigue crack propagation rate varies linearly with both stress ratio range and stress intensity factor range, consistent with experimental findings. The results of the opening and closing evolution of the crack tip are consistent with the law of crack propagation, which indicates that the plastic behavior of the crack tip can be effectively characterized by the CCZM. Furthermore, parameters obtained from the cyclic cohesive zone model's Paris formula closely match experimental data, thus validating its accuracy and feasibility in simulating fatigue crack propagation behavior.
Abstract
15MnTi steel is widely used in high load structures such as bridges, pressure vessels, ships, and vehicles due to its excellent mechanical properties. In the course of service, [...]
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Numerical simulation of the swelling and deswelling process of gel
I. Riku, K. Mimura

WCCM2024.

Abstract
It is well known that the entropy elasticity of rubberlike materials and Brownian motion are described by formally analogous equations as both originated from thermal fluctuations. In rubberlike materials, the shear modulus is conventionally considered to be proportional to the absolute temperature and the proportionality factor is the number density of polymer chains for an affine polymer chains’ network model. On the other hand, the self-diffusion coefficient of Brownian motion is described as the product of the mobility and the absolute temperature. However, for the polymer chains’ network in a solvent, the interaction between the polymer chains and the solvent molecules occurs and the collective diffusion coefficient of the solvent molecules should be different to the self-diffusion coefficient of Brownian motion. Moreover, the shear modulus of the resultant polymer gel should be dependent on the swelling ratio due to the nonaffine movement of polymer chains. Therefore, to verify the analogy of the equations for the shear modulus of the nonaffine polymer chains’ network model and the collective diffusion coefficient of the solvent molecules, in this study, the swelling and deswelling process of the polymer gel is investigated by the numerical simulations.
Abstract
It is well known that the entropy elasticity of rubberlike materials and Brownian motion are described by formally analogous equations as both originated from thermal fluctuations. [...]
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Numerical studies of compression failure in triply periodic minimal surface-based ceramic foams
T. Tran, R. Piat

WCCM2024.

Abstract
Microstructures with minimal surfaces can be often found in natural porous architectures, where the surface tension minimizes the area. The triply periodic minimal surfaces (TPMS) [1] are an example of such microstructures. Compared with other porous structures, TPMS have three significant features: firstly, their geometries can be completely expressed via analytical functions; secondly, TPMS are periodic in three independent directions and thirdly, the mean curvature of TPMS is zero [2]. Transforming the TPMS-based unit cell into a lattice structure has particular usage in aerospace, nuclear energy, and biomedical applications where light weight, high stiffness, and temperature resistance are of critical importance. In the presented studies, the failure behavior of four typical TPMS structures (Primitive, Gyroid, Neovius, and IWP) under compression was studied using finite element analysis. Numerical modeling of the damage propagation and strength prediction was performed by removing the finite elements in which the appropriate damage criterion is reached. Utilizing the equations of the generated TPMS structures, the wall thickness of unit cell was considered the main parameter that defined the ceramics volume fraction and should be taken into consideration. Therefore, various unit cell models for different wall thicknesses were generated and used to investigate the impact of the cell geometry on the damage initiation, propagation, and overall compression strength. The results of compression strength and damage development were compared with those of other TPMS structures for the same wall thickness and volume fraction. Finally, the grade TPMS porous structure was provided to verify the effect of wall thickness variation on damage evolution on the macroscale.
Abstract
Microstructures with minimal surfaces can be often found in natural porous architectures, where the surface tension minimizes the area. The triply periodic minimal surfaces [...]
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Penetration resistance of graphene coated ceramic materials under projectile impacts
M. Talebi Bidhendi, K. Behdinan

WCCM2024.

Abstract
Extreme conditions including impact can result in material degradation, permanent damages, and occasionally property/life loss. Therefore, investigation of materials and structures under projectile impact has been a canonical field of research over the past decades. Such studies have led to the development of hybrid materials with high performance and durability under the aforementioned loading. As an emerging hybrid material, graphene oxide (GO) - silicon carbide (SiC) provides promising thermo-chemo-mechanical properties with various applications in defense, energy, and aerospace engineering. Nevertheless, penetration resistance of such composites under impact received less attention due to experimental and computational difficulties. Here, ReaxFF molecular dynamics is leveraged to address the aforesaid problem around room temperature. In that regard, the response of 4H-SiC thin films coated by GO samples under indentation and high-velocity projectile impact is studied. It is observed that (a) ceramic substrates coated by GO samples with higher functional groups concentration (oxidation degree) demonstrate softer behavior under indentation, and (b) fracture and penetration resistance under high-velocity impact are altered based on the oxidation degree of the coating layers. In essence, impact-induced complete perforation becomes more localized to the impacted region by increasing the oxidation content of the coating layers. The influence of oxygen functional groups on the adhesion energy between GO and SiC layers is also investigated. It is observed that adhesion energy between SiC and the coating can be ameliorated by the oxidation degree of the graphene samples. Eventually, the above-mentioned findings provide some insights into the bottom-up design pathways for developing ceramic-based protective barriers in which GO is used as a coating layer or reinforcement
Abstract
Extreme conditions including impact can result in material degradation, permanent damages, and occasionally property/life loss. Therefore, investigation of materials and structures [...]
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A primal hybrid finite element method to solve general compressible, quasi-incompressible and incompressible elasticity using stable H(div)-L2 spaces
P. Devloo, G. Avancini, N. Shauer, H. Oliveira

WCCM2024.

Abstract
Hybrid methods are usually derived from an extended variational principle, in which the interelement continuity of the functions subspace is removed and weakly enforced by means of a Lagrange multiplier. In this context, a new primal hybrid finite element formulation is presented, which uses H(div) conforming displacement functions and discontinuos L2 approximation for pressure together with shear traction functions to weakly enforce tangential displacement. This combination allows the simulation of compressible, quasi-incompressible and fully incompressible elastic solids, with convergence rates independent of its bulk modulus. The proposed approach benefits from the property that the divergence of the H(div) displacement functions is De Rham compatible with the (dual) pressure functions. The hybridization of the tangential displacements is weakly enforced through a lower order shear stress space. This leads to a saddle-point problem that is stable over the full range of poisson coefficient (large compressibility up to incompressible). Moreover, a boundary stress (normal and shear) can be recovered that satisfies elementwise equilibrium. Hybridizing the tangent stresses and condensing the internal degrees of freedom, a positive-definite matrix with improved spectral properties can be recovered. The stability, consistency and local conservation features are discussed in details. The formulation is tested and verified for different test cases.
Abstract
Hybrid methods are usually derived from an extended variational principle, in which the interelement continuity of the functions subspace is removed and weakly enforced by [...]
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Complete variable kinematic cuf-based multilayered shell elements
E. Carrera, D. Scano

WCCM2024.

Abstract
The paper presents a methodology for formulating multi-layered composite shell theories with arbitrary kinematic fields. Each displacement variable is examined through an independent expansion function, allowing integration of equivalent single layer and layer-wise approaches within the Carrera Unified Formulation. Finite element method discretizes the structure in the reference plane of the plate using Lagrange-based elements. Governing equations are derived using the principle of virtual displacements. The study considers multilayered structures with different radius-to-thickness ratios and compares results with analytical solutions from the literature. Findings suggest the most appropriate model selection depends strongly on specific problem parameters
Abstract
The paper presents a methodology for formulating multi-layered composite shell theories with arbitrary kinematic fields. Each displacement variable is examined through an [...]
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Band gap evolution in nonlinear dynamics of metamaterials made structures via gradually-changing mechanical properties
R. Augello, E. Carrera

WCCM2024.

Abstract
This paper explores the dynamic behavior of metamaterial-like structures by investigating the evolution of their band gap under the influence of geometrical nonlinearities in the large displacement/rotations field. The study employs a unified framework based on the Carrera Unified Formulation (CUF) and a total Lagrangian approach to develop higher-order onedimensional beam theories that account for geometric nonlinearities. The axis discretization is achieved through a finite element approximation. The equations of motion are solved around nonlinear static equilibrium states, which are determined using a Newton–Raphson algorithm combined with a path-following method of arc-length type. The CUF approach introduces two key innovations that are highly suitable for the evolution of the band gap: 1) Thin-walled structures can be effectively represented using a single one-dimensional beam model, overcoming the common limitations of standard finite elements. This is crucial as three-dimensional solid elements would result in significant computational costs, and twodimensional elements pose limitations for this type of investigation. Finally, employing onedimensional finite elements usually requires a combination of elements, leading to additional mathematical complexities in their connections and lacking geometric precision. 2) CUF enables the use of the full Green-Lagrange strain tensor without the need for assumptions, as is the case with von Karm´ an nonlinearities. ´ The paper specifically compares results obtained with linear and nonlinear stiffness matrices, highlighting the differences. Numerical investigations are conducted on thin-walled structures composed of repeatable cells, assessing mode changes under traction and compression loading. The findings emphasize that the band gap is an inherent property of the equilibrium state, underscoring the necessity of a proper nonlinear analysis for accurately evaluating frequency transitions
Abstract
This paper explores the dynamic behavior of metamaterial-like structures by investigating the evolution of their band gap under the influence of geometrical nonlinearities [...]
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A compact sixth order finite difference scheme for the 3D Poisson equation
C. Kavouklis

WCCM2024.
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Discretization error estimation for flow simulations using general hybrid grids
Y. Kallinderis

WCCM2024.

Abstract
A primary area of the author’s work with his students is outlined in the present article. It regards the estimation of the discretization error with mixed-element and adaptive meshes. Use of general hybrid meshes for computational flow simulations is of importance due to the complexity of both the geometry and the fields. The meshes can consist of a mix of hexahedra, prisms and tetrahedra with pyramids being transitional elements. The discretization error is a primary component of the numerical error in flow simulations. Primary factors affecting it are the local density of the mesh, as well as its “distortions”, namely the variation in local size and orientation (stretching, skewness), the shape of the individual elements (shear, twist), and the local change in their type (grid interfaces). Two distinct approaches have been followed in order to estimate and control the discretization error. The grid-based (“a priori”) approach assesses mesh quality from the analytic expression of the truncation error. The solution-based (“a posteriori”) approach monitors approximations of the variation of flow quantities (“sensors”). Those are then applied to guide adaptation of the grid to the simulated flow field
Abstract
A primary area of the author’s work with his students is outlined in the present article. It regards the estimation of the discretization error with mixed-element and adaptive [...]
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3D-ACA for the time domain boundary element method: Comparison of FMM and H-matrix based approaches
M. Schanz

WCCM2024.

Abstract
The time domain Boundary Element Method (BEM) for the homogeneous wave equation with vanishing initial conditions is considered. The generalized convolution quadrature method (gCQ) developed by Lopez-Fernandez and Sauter is used for the temporal discretisation. The spatial discretisation is done classically using low order shape functions. A collocation approach is applied. Essentially, the gCQ requires to establish boundary element matrices of the corresponding elliptic problem in Laplace domain at several complex frequencies. Consequently, an array of system matrices is obtained. This array of system matrices can be interpreted as a threedimensional array of data which should be approximated by a data-sparse representation. The generalised Adaptive Cross Approximation (3D-ACA) can be applied to get a data sparse representation of these three-dimensional data arrays. Adaptively, the rank of the three-dimensional data array is increased until a prescribed accuracy is obtained. On a pure algebraic level it is decided whether a low-rank approximation of the three-dimensional data array is close enough to the original matrix. Within the data slices corresponding to the BEM calculations at each frequency either the standard H-matrices approach with ACA or a fast multipole (FMM) approach can be used. The third dimension of the data array represents the complex frequencies. Hence, the algorithm makes not only a data sparse approximation in the two spatial dimensions but detects adaptively how much frequencies are necessary for which matrix block. Numerical studies show the performance of these methods
Abstract
The time domain Boundary Element Method (BEM) for the homogeneous wave equation with vanishing initial conditions is considered. The generalized convolution quadrature method [...]
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Les energies renovables i el seu desenvolupament: Situació, impacte i objectius.
J. Enrich, M. Reguant, C. Serra-Sala, G. Congrés2025

Abstracts_4rceec (2024). 213
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L’AIGUA REGENERADA PER ASSEGURAR LA RESILIÈNCIA ECONÒMICA, SOCIAL I AMBIENTAL DE CATALUNYA
M. Hernan, G. Congrés2025

Abstracts_4rceec (2024). 214
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Random Dense Packing of Continuous Distributions of Spherical Particles - Use of Particle Packing Model and Discrete-Particle-Method to predict Particle Spacing Factors
T. Stengel, F. Wiese, N. Obermeier

particles2023.

Abstract
Portland Cement (PC) is responsible for about 8% of global CO2 emissions and is mainly used as a binder in concrete, which is a basic material for all types of load-bearing structures. Due to its versatile usage (precast or ready-mix concrete) and availability almost all over the world, concrete is used in a wide range of applications. When looking at possible pathways to reduce the carbon footprint four measures emerge: 1. 2. 3. 4. Use of renewable energy for PC production (mainly clinker burning process) CO2 capture during PC production. Use of supplementary cementitious materials to reduce the amount of PC. Optimization of PC efficiency within the concrete to reduce the amount of PC needed. To optimize the efficiency of PC, particle packing methods can be used, see e.g. [1], [2]. A well-established geometrical particle packing model is the compressible packing model (CPM) [3], which was extended to the compressible interaction packing model (CIPM) to account for colloidal interactions [4]. Based on the CIPM a so-called cement-spacing-factor (CSF) is calculated [2], [4] by dividing the PC volume in concrete by the maximum packing density (PD). CSF is then used to optimize PC efficiency, i.e., strength of PC based materials. However, CSF calculated based on PD is only an auxiliary parameter (i.e., particle saturation on a volume base), which at best qualitatively describes PC spacing in a particle arrangement and does not take the spread of the PC spacing into account. In this paper, a DEM-based enriched particle packing algorithm is developed that accounts for particle type (i.e., inert particles or PC) and distribution of PC particle distance. The results are compared to strength tests on PC-based pastes and the correlation to the calculated distribution of PC particle distance is shown. Based on PD calculations and the enriched DEM particle packing algorithm an optimization of PC efficiency in concrete can be performed.
Abstract
Portland Cement (PC) is responsible for about 8% of global CO2 emissions and is mainly used as a binder in concrete, which is a basic material for all types of load-bearing [...]
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Particle- based Simulation of Crack Propagation in Structural Connections Produced with Direct Energy Deposition 3D- Printing
J. Olsson, M. Ander, S. Larsson, O. Borgström, E. Tibuzzi, P. Barden, C. Williams

particles2023.

Abstract
This paper explores how Force Flux Peridynamics (FFPD) can support the design of lightweight metal components in building structures produced with Direct Energy Deposition (DED) Additive Manufacturing (AM). DED is a relatively new technology that deposit metal layer-by-layer to create three-dimensional structures without the need for support structures. This process has the potential to significantly reduce the embodied carbon in building structures by reducing the weight of the structural connections and hence the weight of all other structural components [4]. However, the process applied in AM for metals can make the printed objects susceptible to defects which may compromise their structural integrity and may even lead to fracture [5]. In this paper we describe a design process for the creation of lightweight structural components while including modelling of anisotropy, yielding and brittle fracture. The central core of the process is the application of a particle method called Force Flux Peridynamics (FFPD) which is used to predict yielding and fracture. The paper thus builds upon strategies developed and defined in other publications including; the derivation of the FFPD particle method [2], a strategy for calibration of materials in paper [1], a motivation to apply this concept in the context of nodal connections for spatial structures as described in paper [3]. The specific nodal connection that is analysed in this paper is designed for rotational DED printing which creates a component with radial anisotropic mechanical properties. The node is analysed using an axial tensile and an axial compression load case where the load is applied by imposing incremental translations to the attachments where the structural members would be connected. The susceptibility to fracture in relation to the anisotropy of the printed metal is discussed.
Abstract
This paper explores how Force Flux Peridynamics (FFPD) can support the design of lightweight metal components in building structures produced with Direct Energy Deposition [...]
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Numerical Investigation of the Installation of Suction Caisson in Sand Using Material Point Method
M. Alturki, L. Zambrano-Cruzatty, A. Faramarzi, M. Mehravar

particles2023.

Abstract
Suction caisson has gained interest in recent years as an alternative foundation for offshore wind turbines due to its cost-effectiveness and easy installation compared to conventional foundations such as monopile. After initial penetration due to its self-weight, suction is applied until the caisson reaches the desired depth. Applying suction provides additional driving force due to the pressure difference between inside and outside the caisson and induces seepage that degrades friction and tip resistance, which further facilitates the installation. The seepage plays a vital role in installing suction caisson in sand; however, it might change the soil state which affects the ultimate bearing capacity of the caisson. Several research works have been conducted to study the suction caisson installation in sand. However, the complexities of the problem including large deformation, solid-fluid and soil-structure interaction, inhibited these studies from fully understanding the installation mechanism. This paper proposes a large deformation modeling framework by using the material point method (MPM). MPM is a hybrid Lagrangian-Eulerian particle-based method that uses material points over a fixed computational mesh where governing equations are solved. During the convection of the particles, the background mesh is kept fixed, making it suitable for large deformation problems. The model considers soil-structure interaction by adopting a Coulomb contact algorithm between the caisson and surrounding soil. In this paper, the stability of the contact algorithm is ensured by correcting material point velocities in the vicinity of the caisson interface using a limiting velocity based on the element size and time step. The framework is validated by comparing a simulation of caisson installation under constant velocity with results published in the literature. Our proposed framework’s results agree with previous published results, demonstrating that the simplified stabilization procedure does not affect the simulation results. This is a promising result that will enable the incorporation of fully coupled analysis to better understand the effects of induced seepage on the installation mechanism of suction caissons.
Abstract
Suction caisson has gained interest in recent years as an alternative foundation for offshore wind turbines due to its cost-effectiveness and easy installation compared to [...]
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NONLINEAR ANALYSIS OF SOLAR FLARES OF X CLASS
L. Shakaraliyeva

International Journal of Multidisciplinary Educational Research and Innovation (2024). 1

Abstract
The study of solar flares is definitely very important for our planet, because they have a direct impact on it. We have always wondered how solar flares, seemingly so far away from us, can affect the Earth. They are known for their effect on the ionosphere and magnetic field of our planet, thereby causing negative effects in addition to the fascinating aurora borealis. Thus, every flare that occurs on our main luminary can cause geomagnetic storms, bringing massive power outages, malfunctioning GPS systems, radio and telecommunications. In studying this issue, we decided to understand their patterns. Thus, we studied methods of processing large volumes and presenting them in the form of graphs using MATLAB and Python programs, while using the relationship between the characteristics of the radio signal and its topology, developed by our scientist Zhanabaev Z.Ch. The uniqueness of our project is the use of only two coefficients (two-dimensional shape coefficient and information-entropy) characterizing solar flares to determine their patterns. In conclusion, having set the goal of the project is to find the most efficient method to predict solar flare based only on the value of second flux and soft X-ray emission. We were able to make progress and discover a new to science concept of self-organization of solar flares.
Abstract
The study of solar flares is definitely very important for our planet, because they have a direct impact on it. We have always wondered how solar flares, seemingly so far [...]
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REFORMA DE L’ADMINISTRACIÓ I QUALITAT INSTITUCIONAL
Q. Brugué, G. Congrés2025

Abstracts_4rceec (2024). 211
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La relació proveïdor-finançador com a element determinant de la sostenibilitat del sistema sanitari públic
G. Congrés2025

Abstracts_4rceec (2024). 210
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Catalunya Media City: a key infrastructure for the catalan and European audiovisual industry
J. Pujol, E. Cluster, M. Rutllant

Abstracts_4rceec (2024). 212

Abstract
• The Catalunya Media City project aims to create an Audiovisual, Digital and Video Game Hub, a global reference in training, research, creation and innovation. • The project is conceived as a Hub open to citizens and in dialogue with the environment, located both in the Tres Xemeneies area, specifically in the Nau Turbines, in the Tres Xemeneies buildings and adjacent spaces, as well as in Terrassa , in the Audiovisual Park. • The infrastructure must become a strategic asset for the development of local industry, the attraction of talent and Investments. • The Besòs project, together with the Terrassa Audiovisual Park, will make Catalonia a country of reference in the field of cultural industries related to digital, audiovisual and video games. • Work is currently underway on the preparation of the functional plan, which will serve to define and propose the occupation and distribution of the different spaces of the future Catalunya Media City, and contacts are being maintained with the sector to establish synergies and possible col· works
Abstract
• The Catalunya Media City project aims to create an Audiovisual, Digital and Video Game Hub, a global reference in training, research, creation and innovation. • [...]
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An Innovative Technique to Measure Lateral Pressure of Self-Compacting Concrete Using Fiber Bragg Grating Sensor
P. Shakor, . Nadarajah, P. Stocker, J. Chen

(2024).

Abstract
Self-compacting concrete (SCC) is the mostﬂowable concrete type that exerts high pressure on formwork. SCC is the most commonly used concrete globally for construction applications due to its cost-effectiveness. However, to make a formwork resist the exerted lateral pressure of SCC, it is required to have a suitable design for formwork. This paper presents a novel approach on how could create and prepare the Fiber Bragg Grating (FBG) optics using as a sensor to measure lateral pressure and temperature of SCC. To ensure the FBG sensor works properly a validated methodology is conducted. In theﬁrst stage, FBG sensors are calibrated with temperature sensitivity and then are calibrated with water pressure. The latter calibration is used to verify lateral pressure with SCC. However, this is not the only sensor used to record the result, a genuine sensor such as a transducer sensor has been positioned close to the FBG sensor to validate the results of the FBG sensor. The created FBG sensor demonstrates highly promising results, effectively validating the outcomes of the transducer sensor, while also reducing costs and enhancing usability for construction applications.
Abstract
Self-compacting concrete (SCC) is the mostﬂowable concrete type that exerts high pressure on formwork. SCC is the most commonly used concrete globally for construction applications [...]
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CAPÍTULO 16. GESTIÓN DEL RESIDUO Y TECNOLOGÍAS DE REUSO DE MATERIALES COMPUESTOS NO POLIMERIZADOS
X. Martinez

libro-blanco-materiales-compuestos (2024). 2

Abstract
This chapter addresses two relevant challenges to enforce in a manufacturing plant where carbon fiber prepreg is used as raw material for the manufacture of aeronautical parts. The first challenge is the segregation of fresh production waste, where the resin is fresh and has a big potential for being used as material for other applications. This chapter described a proposal for the collection of this highly valuable material in a pilot plant where aircraft stabilizers are manufactured. This second challenge addresses solutions for the reprocessing of waste material discarded during the manufacturing of carbon parts. Hereafter is described the preparation of new materials or by-products, which can be reincorporated into the production system of other composite material parts.
Abstract
This chapter addresses two relevant challenges to enforce in a manufacturing plant where carbon fiber prepreg is used as raw material for the manufacture of aeronautical parts. [...]
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Multi-scale procedure for the mechanical analysis of composite laminate structures considering mixed boundary conditions
F. Turon, F. Otero, X. Martinez

(2023).

Abstract
This paper presents a multi-scale procedure for the study of flat composite structures with discontinuities. In this procedure, the structure is solved using shell elements while the laminate performance and the structural discontinuities (e.g. connections or change in the laminate thickness) are analysed with a subscale model made with solid 3D elements. The kinematics of both models are coupled following the Kirchhoff–Love theory. This coupling is used during the homogenization procedure where the characteristic behaviour of the different micro-models is obtained. Periodical boundary conditions are used for the laminates whereas a combination between periodical and linear boundary conditions are used for the discontinuities. The proposed procedure allows to reproduce accurately the structure elastic behaviour, as well as the stress and strain states in regions with discontinuities, which until now could only be accurately simulated by means of expensive numerical models using volumetric solid elements.
Abstract
This paper presents a multi-scale procedure for the study of flat composite structures with discontinuities. In this procedure, the structure is solved using shell elements [...]
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La influencia del modelo de gestión en el consumo doméstico de agua en Catalunya
M. Iglesias

Abstracts_4rceec (2024). 207
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Multiscale modeling of prismatic heterogeneous structures based on a localized hyperreduced-order method
A. Giuliodori, J. Hernández, E. Soudah

Computer Methods in Applied Mechanics and Engineering (2023). Volume 407, 15 March 2023, 115913

Abstract
This work aims at deriving special types of one-dimensional Finite Elements (1D FE) for efficiently modeling heterogeneous prismatic structures, in the small strains regime, by means of reduced-order modeling (ROM) and domain decomposition techniques. The employed partitioning framework introduces “fictitious” interfaces between contiguous subdomains, leading to a formulation with both subdomain and interface fields. We propose a low-dimensional parameterization at both subdomain and interface levels by using reduced-order bases precomputed in an offline stage by applying the Singular Value Decomposition (SVD) on solution snapshots. In this parameterization, the amplitude of the fictitious interfaces play the role of coarse-scale displacement unknowns. We demonstrate that, with this partitioned framework, it is possible to arrive at a solution strategy that avoids solving the typical nested local/global problem of other similar methods (such as the FE2method). Rather, in our approach, the coarse-grid cells can be regarded as special types of finite elements, whose nodes coincides with the centroids of the interfaces, and whose kinematics are dictated by the modes of the “fictitious” interfaces. This means that the kinematics of our coarse-scale FE are not pre-defined by the user, but extracted from the set of “training” computational experiments. Likewise, we demonstrate that the coarse-scale and fine-scale displacements are related by inter-scale operators that can be precomputed in the offline stage. Lastly, a hyperreduced scheme is considered for the evaluation of the internal forces, allowing us to deal with possible material nonlinearities.
Abstract
This work aims at deriving special types of one-dimensional Finite Elements (1D FE) for efficiently modeling heterogeneous prismatic structures, in the small strains regime, [...]
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Final open-door industrial day
F. Rechsteiner, V. Mathes

Fibregy OA (2024). Vol. Public Deliverables, 34

Abstract
The final open-door industrial day forms the final milestone of the project (MS 20) and thus the project completion. The event will take place again at one of the partners sites. During the meeting the project results are presented comprehensively. The prototypes should also be shown again. In terms of content, the following points are in the foreground: Results of life cycle assessment and waste management, global business plan, standardization recommendations, final conclusions. (D7.12)
Abstract
The final open-door industrial day forms the final milestone of the project (MS 20) and thus the project completion. The event will take place again at one of the partners [...]
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First open-door industrial day
F. Rechsteiner, V. Mathes

Fibregy OA (2024). Vol. Public Deliverables, 33

Abstract
The focus of the First open-door industrial day is on the presentation of the real scale demonstrators. Accordingly, the meeting should take place at one of the partners who is working on the demonstrators or where they are being produced. Among other things, the materials used (materials' catalogue), guidelines, the construction process, structural health monitoring (SHM system), tests and prototypes (D7.8) should be presented. The aim of this meeting is, among other things, addressing various stakeholders and bringing the project results further into the public eye. Accordingly, the aim is to also invite external project representatives to the open-door industrial day, if possible. The agenda should be limited to one day in order to make a visit as uncomplicated as possible, even without an overnight stay. In addition, the ongoing project progress is discussed if necessary.
Abstract
The focus of the First open-door industrial day is on the presentation of the real scale demonstrators. Accordingly, the meeting should take place at one of the partners who [...]
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Second information day
F. Rechsteiner, V. Mathes

Fibregy OA (2024). Vol. Public Deliverables, 32

Abstract
The second information day will be held after 18 months. As the first information day, it is planned as a presence event. The agenda will be planed for 1 to 1 ½ days. The event will take place again at one of the project partners. Focus of the agenda will be the project progress and presentation of further activities. A special focus will be on the market analysis and the OWTP concept. A workshop with the Standard Committee (D7.6) will complete the project meeting.
Abstract
The second information day will be held after 18 months. As the first information day, it is planned as a presence event. The agenda will be planed for 1 to 1 ½ days. The [...]
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First information day
F. Rechsteiner, V. Mathes

Fibregy OA (2024). Vol. Public Deliverables, 31

Abstract
After 6 months, the first information day will be the first joint meeting of the entire project consortium. A presence event is currently assumed. Should the situation (Covid-Pandemic) make it necessary for the event to be held virtually, the agenda will be adjusted if necessary. 1 to 1 1/2 days are estimated for this information day. The meeting will take place at one of the project partners. It starts at noon on the first day. The first day ends with a consortium-dinner. The meeting will continue on the second day. In terms of content, the focus will be on the following points: Presentation of the project objectives of the project progress and the expected results. During the meeting, the first results of the ongoing and possibly completed WPs should be presented. There is also a workshop with the Standardization Committee (D7.3) planned. In addition to the purely professional exchange, the meeting also allows you to get to know the project partners personally.
Abstract
After 6 months, the first information day will be the first joint meeting of the entire project consortium. A presence event is currently assumed. Should the situation (Covid-Pandemic) [...]
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Measurements report
A. Rodríguez, R. Andrés, J. Ruiz, P. Ropero, A. Pastor, J. Garcia Espinosa

Fibregy OA (2024). Vol. Public Deliverables, 30

Abstract
The measurement report will include the testing methodology and the results of the ocean sea trials of the 1:6 W2Power steel-based prototype with the FRP-based towers installed to hold the wind turbine generators. Considering that the trials will last 3-5 months, sets of data will be collected and analyzed to assess the metocean effects on the platform, ensure the technical feasibility of the towers in composites and validate the different monitoring systems developed in FIBREGY. In overview, the following industrial and technological achievements will be explained in the measurements report: 1st) guidelines for the installation of the FRP towers in the existing steel-based W2 Power prototype, 2nd) Installation of a SHM system based on accelerometers, strain gauges, and fiber optics in the FRP towers, 3rd) analysis of the results derived from the SHM system installed in the offshore platforms, 4th) conclusions regarding how useful are the obtained data for the digital twin model developed in WP3 to assess the structural integrity of the platforms, and 5th) analysis and conclusions of the influence of the metocean conditions in the structural integrity of the FRP-based towers installed on scaled W2Power prototype.
Abstract
The measurement report will include the testing methodology and the results of the ocean sea trials of the 1:6 W2Power steel-based prototype with the FRP-based towers installed [...]
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Development of the CAE models
J. Jurado

Fibregy OA (2024). Vol. Public Deliverables, 29

Abstract
The report will summarize the work to be carried out in subtask 6.3.1, related to the generation of two complete 3D CAE models of the structure of the W2Power platform and TIDETEC turbine housing, based on the hydro-elasticity and degradation model developed in WP3. These models will be used in WP4 to perform a final strength and degradation assessment of the structure.
Abstract
The report will summarize the work to be carried out in subtask 6.3.1, related to the generation of two complete 3D CAE models of the structure of the W2Power platform and [...]
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Construction of the W2Power real-scale demonstrator
E. Waldura, J. Clement, E. Cochelin

Fibregy OA (2024). Vol. Public Deliverables, 28

Abstract
Deliverable 6.4 is a full scale demonstrator made up of 2 main connection part of a floating windturbine platform. The parts will be made of GRP with an estimated height of 9.2m. This demonstrator should be built by month 30.
Abstract
Deliverable 6.4 is a full scale demonstrator made up of 2 main connection part of a floating windturbine platform. The parts will be made of GRP with an estimated height of [...]
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Construction of the turbine housing demonstrator
M. Moutinho, R. Ferreira, C. García

Fibregy OA (2024). Vol. Public Deliverables, 27

Abstract
This deliverable will include the Tidetec’s turnable turbine housing large demonstrator and a related detailed report in which the design process of the respective tooling (mandrels) and filament winding process simulation and manufacturing will be described
Abstract
This deliverable will include the Tidetec’s turnable turbine housing large demonstrator and a related detailed report in which the design process of the respective tooling [...]
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Construction of the W2Power tower demonstrator
E. Waldura, J. Cardoso

Fibregy OA (2024). Vol. Public Deliverables, 26

Abstract
Deliverable 6.2 is a demonstrator of the tower of the W2Power floating windturbine at scale of 1/6. The demonstrator made of GRP will have a estimated dimension of 10m with a diameter of 1.5m. This demonstrator should be built by month 24. This deliverable will be public.
Abstract
Deliverable 6.2 is a demonstrator of the tower of the W2Power floating windturbine at scale of 1/6. The demonstrator made of GRP will have a estimated dimension of 10m with [...]
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Middle scale test on dry coatings and connections
O. Chan Taw, J. Clement, E. Cochelin

Fibregy OA (2024). Vol. Public Deliverables, 25

Abstract
The report of deliverable 6.1 will be split into 2 parts: The first part will present the results of the performance tests on dry coating in realistic offshore conditions and on larger samples. After the coupon level evaluations performed un WP2, several larger scale tests will be conduct. The configurations to be tested will be selected according to the WP2 outputs. Samples with and without integrated sensors will be compared as well. Recommendations for improvement of the process for both adhesive paint film and in-mold paint film will be done in accordance with the results. For emerged composite parts, a natural outdoor exposure site will be used. This consists in an exposition in open air or under shelters in a tempered marine atmosphere site. Various exposure angles can be chosen (45° south, 5° south, 90° north) and all the conditions are properly monitored. For immersed composite parts, tests in natural seawater will be conduct. The water can be regulated in temperature, oxygen and biological content. This test is performed on land and is able to give representative data on the durability and biofouling behavior of the products. The second part of the deliverable will presents the results from the static and dynamic tests performed for selected adhesive connections. Then, the reduction factors, used for a complete fatigue calculation, will be determined and presented. And finally, in the case of reversible structural adhesive, results going from the comparison with traditional adhesives until the capacity to recycle them, evaluating the heat energy and the time needed to separate the bonded joint, will be presented.
Abstract
The report of deliverable 6.1 will be split into 2 parts: The first part will present the results of the performance tests on dry coating in realistic offshore conditions [...]
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Guidance notes for the production of large FPR OWTP
J. Cardoso, N. Goutay, A. Comer, A. Hejjaji, G. Bhatia

Fibregy OA (2024). Vol. Public Deliverables, 24

Abstract
Description of the technologies and processes developed in the project for the production of the targeted OWTP platforms as well as manufacturing strategies for modular production. Furthermore, it will also contain a brief summary of the two open-door days and workshops, which will be organized
Abstract
Description of the technologies and processes developed in the project for the production of the targeted OWTP platforms as well as manufacturing strategies for modular production. [...]
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Report on recommendations for predictive maintenance of FRP-based OWTP platforms (T4.4)
C. García, M. Moutinho

Fibregy OA (2024). Vol. Public Deliverables, 23

Abstract
This report will gather recommendations and procedures to be considered in the analysis of predictive maintenance in OWT platforms built in FRP materials, considering the different SHM strategies, instrumentation and a digital twin models developed in the context of FIBREGY. It should be noted that the diagnosis of the marine offshore structures will be based on the variations of various key performance indicators (KPIs), which will provide real-time information about the damage state and structural condition of the offshore platforms, including KPIs related to the onboard equipment and systems if needed. Special attention will be also paid to the optimum number and location of the sensors to be embedded in the offshore platforms.
Abstract
This report will gather recommendations and procedures to be considered in the analysis of predictive maintenance in OWT platforms built in FRP materials, considering the [...]
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Project guidelines and recommendations for using FRP in large OWTPs
J. Petiteau, S. Paboeuf

Fibregy OA (2024). Vol. Public Deliverables, 22

Abstract
The project guidelines will define the methodology for the design assessment, the performance criteria to be applied and recommendations for the construction of OWTP in FRP. The report will also identify possible gaps and deviation for the certification
Abstract
The project guidelines will define the methodology for the design assessment, the performance criteria to be applied and recommendations for the construction of OWTP in FRP. The [...]
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Critical review of applicable standards and gaps identification in FRP offshore structures (T4.3.1)
E. Sanchez, C. García, A. Jurado, J. Petiteau, S. Paboeuf, R. Zaringue, P. Ropero

Fibregy OA (2024). Vol. Public Deliverables, 21

Abstract
The conclusions of an extensive review of the regulations and standards related to the use of conventional (steel and concrete) and unconventional materials (FRP materials and others) on marine structures will be included in this report, as well as the gaps that need to be filled in in the future by regulatory bodies to enable the rolling out of OWTP platforms in FRP materials. A two-tier strategy will be performed with the fundamental objective to carry out the critical review. Firstly, it will be carried out an analysis of the potential standards for the application of FRP materials in the design of offshore structures. Secondly, it will be identified the existing gaps for the application of FRP materials in the design of the W2Power and the TIDETEC’s turntable tidal turbine developed in FIBREGY. The findings of this report will be used as the background of the deliverable 4.7 focused on the development of project design guidelines and recommendations for using FRP in large OWTPs.
Abstract
The conclusions of an extensive review of the regulations and standards related to the use of conventional (steel and concrete) and unconventional materials (FRP materials [...]
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Multifunctional materials for SHM diagnosis and structural performance assessment
C. García, B. Fernandes, R. Mendes, F. Otero

Fibregy OA (2024). Vol. Public Deliverables, 20

Abstract
This report will evaluate the structural health monitoring (SHM) methodology developed in the framework of FIBREGY to obtain the damage state of the fibre-based structural elements used in offshore platforms. The non-destructive vibration-based methodology deals with the variations of the key performance indicators (KPIs, e.g. overall vibration energy, damping, etc.) which are influenced by the presence of damage in the FRP materials. To assess the damage state of the multifunctional materials, a set of sensors and/or optical fibers will be interleaved in the interlaminar regions of the FRP-based materials used in the marine structures. Initially, the main scope of this report is to explore the selection of the most suitable sensors to manufacture the multifunctional materials. Subsequently, the mechanical performance of the multifunctional materials will be analyzed with the paramount purpose to evaluate the possible weakness of the material induced by the embedding of the sensor. Last, it will be considered the testing of different specimens of multifunctional materials and the preparation of the best strategy for the validation of the monitoring system in a real-case through one of the WP6 demonstrators (FRP-based towers).
Abstract
This report will evaluate the structural health monitoring (SHM) methodology developed in the framework of FIBREGY to obtain the damage state of the fibre-based structural [...]
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Connections in offshore structures
B. Fernandes, J. Nuno-Silva, J. Cardoso, M. Moutinho, F. Otero, P. Ropero, O. Chan Taw, R. Mendes

Fibregy OA (2024). Vol. Public Deliverables, 19

Abstract
Report containing a benchmark of the connection technologies in OWTP structures, their respective evaluation and selection. The report will also include the re-design and optimization of the most promising connections, supported by a detailed description of the experimental testing campaign.
Abstract
Report containing a benchmark of the connection technologies in OWTP structures, their respective evaluation and selection. The report will also include the re-design and optimization [...]
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Environmental protection of composites
O. Chan Taw, A. Comer, N. Goutay, F. Otero

Fibregy OA (2024). Vol. Public Deliverables, 18

Abstract
The report of deliverable D2.3 includes all the results of the durability tests performed during the extensive experimental campaign. The most relevant laboratory tests to evaluate the environmental performance of the various solutions are listed below: - Alternate and continuous immersion in salt solution (ISO 11130, ISO 2812) - High Humidity Test (ISO 6270) - 500 hours at 40 °C and 98 % HR - QUV accelerated weathering test (ISO 11507) - 1000 hours with cycles of 4 hours UV light / 4 hours of high humidity - Climatic chamber with thermal cycles (-20°C / + 80°C) - Adhesion tests: Cross Cut (ISO 2409) and Pull Off (ISO 4624) before and after each ageing test - Gloss (ISO 2813) and Colorimetry (ISO 7724) measurements before and after each ageing test - Observation of visual defects before and after each ageing test - The effect on the texture on biofouling will be evaluated at coupon level in natural sea water basin A dedicated Design of Experiments (DOE) will be built to optimize the number of samples to be tested. The durability will be evaluated for the following configurations: - At least 2 paint references (from 2 suppliers or 2 different chemistries) - At least 2 composite substrates (1 thermoset and 1 thermoplastic) - Three types of application: adhesive paint film, in-mold application of paint film and stand ard liquid paint application - Three surfaces textures: flat surface and two fouling release textures - Unprotected composite samples as a comparison
Abstract
The report of deliverable D2.3 includes all the results of the durability tests performed during the extensive experimental campaign. The most relevant laboratory tests to [...]
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Fatigue performance of composites
A. Comer, A. Hejjaji, G. Bhatia, J. R. Pothnis, J. Cardoso

Fibregy OA (2024). Vol. Public Deliverables, 17

Abstract
The deliverable will present the results and conclusions of the different fatigue tests to be performed. An interim report will be delivered by month M24 describing the regular fatigue tests (O° and 90° lay-ups) and results. This data is the only one required by the numerical models for material calibration. The report will be completed by M29, including the advanced fatigue characterization performed on oblique (45°) lay-ups and also the connections.
Abstract
The deliverable will present the results and conclusions of the different fatigue tests to be performed. An interim report will be delivered by month M24 describing the regular [...]
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FINANÇAMENT DE LES POLÍTIQUES D’ACCÉS A L’HABITATGE SOCIAL DE LLOGUER
A. Gasol

Abstracts_4rceec (2024). 206

Abstract
Considerem que l’habitatge és un pilar clau de l’Estat de Benestar com ho són l’educació, les pensions, la sanitat, o els serveis socials. La gran política habitacional és la que planteja abastir la demanda de parcs d’habitatge públics i socials mitjançant un finançament adient a les seves característiques i necessitats. La comunicació pretén posar l’èmfasi en el finançament de la promoció d’habitatge social de lloguer, pedra angular per tal de proveir a la societat d’un parc que pugui abastar les necessitats sorgides de la darrera crisi financera (2088-2012) que ha suposat un punt d’inflexió en el mercat de l’habitatge, amb un protagonisme molt més accentuat de les transaccions del lloguer. Un canvi estructural produït pel fort augment de la precarietat laboral en determinats col·lectius socials, com ara les rendes baixes, la població estrangera, i els joves. Som del parer que és fonamental blindar el dret a l’habitatge per damunt de la seva consideració com un bé de mercat. La comunicació farà un repàs de les circumstàncies que han conduit a Espanya i a Catalunya a la manca d’un parc d’habitatge social suficient (tant en propietat com de lloguer). Segons la projecció de la creació de noves llars que fa l’INE i el PTSH (Pla territorial sectorial d’habitatge) és necessita la promoció d’habitatge social amb suport de l’Administració Pública a una mitjana de 15.000 habitatges/any, durant els propers 15 anys, una xifra molt allunyada de la producció dels darrers 10 anys. Per tal d’assegurar el finançament de la promoció d’habitatge social de lloguer cal: Continuar comptant amb finançament regular per part del Banc de Desenvolupament del Consell d'Europa (BDCE, CEB), que té com a objectiu millorar les condicions de vida i la cohesió social a Europa mitjançant el finançament de projectes d’alt impacte social, mitjançant la concessió de préstecs i garanties. I també poder accedir al finançament de projectes a llarg termini per part del Banc Europeu d’Inversions (BEI). La provisió d’aquest finançament és bo vehicular-la a través de l’Agència financera tant de l’Estat (ICO) com de la Generalitat de Catalunya (ICF). I, com a novedós, replicar el «Pla d’Inversions per a una Europa Sostenible. Pla d’Inversions del Pacte Verd Europeu» => amb el «Pla d’Inversions per a una Europa Inclusiva. Pla d’Inversions del Pacte d’Habitatge Social Europeu» que garanteixi una vida digna a tota la ciutadania: accedir a un habitatge en condicions assequibles. I així, igual que hi ha el «bo verd europeu» o «BVEu» hi hagi també el «bo d’habitatge europeu» o «BHEu». La pretensió de la Comunicació és que entre tots els agents implicats es pugui aconseguir durant el nou mandat del Parlament Europeu, juntament amb el Consell, adoptar un REGLAMENT (UE) que repliqui el del 2023/2631 de 30.11.2023 sobre els “bons verds europeus”, en aquest cas sobre els “bons d’habitatge social europeus”.
Abstract
Considerem que l’habitatge és un pilar clau de l’Estat de Benestar com ho són l’educació, les pensions, la sanitat, o els serveis socials. La [...]
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Com millorar la col·laboració publicoprivada en el finançament de les concessions de serveis públics
J. MARTÍNEZ VILA

Abstracts_4rceec (2024). 209

Abstract
La Unió Europea tornarà a l’ortodòxia pressupostària dels seus estats, un cop finalitzada la fase post-Covid i amb ell s’acabaran els fons europeus Next Generation. Els països, com l’espanyol, amb dèficits pressupostaris crònics i amb fortes pressions d’augment de la despesa social, tindran dificultats per poder complir les directrius europees i es veuran avocats a una dràstica reducció de la inversió i despesa públiques ja força limitada en els darrers anys. Aquesta previsible menor inversió pública, especialment pel que fa a infraestructures de serveis, només pot ser compensada per part de la iniciativa privada. La realitat actual de projectes d’inversió finançats amb iniciativa publicoprivada és molt minsa, tal com ho testifica l’últim informe de “OIReScon-Oficina Independiente de Regulación y Supervisión de la Contratación” a Espanya, i que està força per sota de la resta de països de la Unió Europea. Les raons que poden justificar aquesta manca de proliferació de noves concessions són de caràcter polític, jurídic, financer i econòmic. Les causes de caràcter polític deriven d’un progressiu distanciament entre el món polític i empresarial, provocant que la capacitat d’inversió a llarg termini de la iniciativa privada s’estigui derivant cap a fora de les nostres fronteres. Cal que les dues bandes de l’equació tornin a apropar posicions i confiança, el més aviat possible, en favor de la nostra economia i la potenciació d’un sector de les infraestructures, generador d’ocupació de qualitat, que havia encapçalat el rànquing internacional sense afectar els pressupostos públics. (En el document desenvoluparé les raons de caràcter jurídic, financer i econòmic) Davant d’aquesta situació, cal fer aportacions que redundin en el foment de la iniciativa privada per a nous projectes d’infraestructures i serveis, en la millora de la governança i en el posicionament polític i social de la col·laboració publicoprivada, en l’adequació dels processos de licitació pública a la realitat actual, en la facilitació de l’adaptabilitat de les concessions actuals a les condicions canviants i millora de la finançabilitat dels projectes, tant des de la perspectiva d’unes condicions atractives de rendibilitat com de la pròpia seguretat jurídica dels projectes. Josep Martínez Vila Conseller Delegat SABA INFRAESTRUCTURAS, S.A.
Abstract
La Unió Europea tornarà a l’ortodòxia pressupostària dels seus estats, un cop finalitzada la fase post-Covid i amb ell s’acabaran els [...]
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Ongoing development of applications of the Cone Penetration Test in interpretation and design
B. Lehane*

ISC2024.

Abstract
This paper presents recent research on the application of the cone penetration test to site characterisation and foundation design. Aspects considered related to characterisation include the interpretation of relative density in granular soils, the derivation of the penetration-velocity characteristic, corrections for shallow penetration and scale effects in laboratory experiments and the influence of particle size on penetration resistance. In relation to foundation design, the paper outlines the nature of CPT-based correlations and describes the development of three types of such correlations for footings, axially loaded piles and laterally loaded piles.
Abstract
This paper presents recent research on the application of the cone penetration test to site characterisation and foundation design. Aspects considered related to characterisation [...]
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The influence of soil structure on CPTu and SDMT results
S. Oberhollenzer*, E. Lande, S. Ritter

ISC2024.

Abstract
The natural structure of clays has a significant influence on its mechanical behaviour and can be characterized using insitu and laboratory tests. It was reported by Robertson (2016) that soil structure leads to an increased tip resistance (qc) and shear wave velocity (Vs) when performing seismic cone penetration tests. However, only limited studies investigated changes in soil structure by means of in-situ tests. Sensitive, marine clays were investigated within the research project "VIBE – Sustainable Ground Improvement Solution for Oslo" at the Norwegian Geo-Test site Onsøy (Gundersen et al. 2019). Possibilities and limitations of the vibro replacement method were studied for very soft ground conditions based on a full-scale field test. The influence of soil structure on in-situ measurements of piezocone penetration tests (CPTu) and seismic flat dilatometer tests (SDMT) are further studied by intentionally disturbing the soil structure by a vibrator. Results of CPTu and Medusa SDMT, executed before and after treatment, are compared to characterize changes in soil structure. The results indicate that the vibration-induced destructuration led to a significant decrease of CPTu measurements, namely tip resistance (qc), sleeve friction (fs) and measured pore pressure (u2), within medium to high sensitive clays. As the decrease in fs is more significant compared to the decrease in qc, a significant decrease in friction ration (Rf) was observed. In analogy, SDMT resulted in a decrease in shear wave velocity (Vs), horizontal stress index (KD) and dilatometer modulus (ED) after the vibro treatment. It was further shown that the soil behaviour type chart according to Robertson (2016) leads to no sufficient characterization of soil structure in soft, marine clays.
Abstract
The natural structure of clays has a significant influence on its mechanical behaviour and can be characterized using insitu and laboratory tests. It was reported by Robertson [...]
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BRIGHT SPARK LECTURE - A Machine Learning Paradigm for Subsurface Stratigraphy from Sparse Data
C. Shi*

ISC2024.

Abstract
Subsurface stratigraphy is an indispensable component of geotechnical site characterization and primarily deals with the interpretation of geological interfaces from site-specific measurements, such as boreholes. Traditional geological profiling methods often rely on engineering judgement for manual drawing or entirely depend on parametric models for interpolation. Both approaches face challenges when dealing with limited geo-data. To effectively address the dilemma, a new machine learning paradigm is proposed in this study to combine valuable prior geological knowledge and sparse site-specific measurements for data-driven predictions of both two-dimensional geological cross-sections and threedimensional geological domains. The valuable prior knowledge is quantitatively represented as training images, which are compiled and stored in a training image database that is further enriched and augmented by employing deep generative models. Subsequently, the optimal training images that are compatible with the available site-specific data are adaptively selected for onward stochastic predictions under the framework of non-parametric Bayesian analysis. The method has been successfully applied to tackle geological profiling challenges in Hong Kong. The proposed framework is demonstrated to be capable of not only predicting the most probable geological patterns but also effectively quantifying associated stratigraphic uncertainty. The framework holds great potential of revolutionizing current engineering practices
Abstract
Subsurface stratigraphy is an indispensable component of geotechnical site characterization and primarily deals with the interpretation of geological interfaces from site-specific [...]
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Interpretation of Cone Penetration Tests in Gravelly Soil
K. Rollins*, J. Roy, A. Walburger, S. Amoroso, R. Dhakal, L. Minarelli, L. Marenghi

ISC2024.

Abstract
Although gravelly soils have been observed to liquefy in 27 earthquakes in the past 120 years, many engineers believe that gravel cannot liquefy due to its high hydraulic conductivity. Gradations from gravel liquefaction case histories have shown these deposits typically contain 25 to 40% sand, reducing the hydraulic conductivity and enabling excess pore pressures to cause liquefaction. While cone penetrometers (CPT), typically used to evaluate liquefaction resistance in sand, may show increases in penetration resistance due to their small diameter relative to gravel particles, the CPT has successfully predicted gravel liquefaction for looser sandy gravels. Case histories in Wellington, New Zealand demonstrate the successful identification of gravel liquefaction hazards using CPT. Although some layers in the profile indicated high penetration resistance, most of the profile was correctly predicted to liquefy. The Soil Behavior Type (SBT) from the CPT did not consistently indicate a sandy gravel profile but was often classified as behaving like a sand or silty sand; likely influenced by higher sand percentages between gravel particles. To evaluate the ability of the CPT to characterize gravelly soils and their liquefaction potential, additional field case histories are desirable. This paper presents test results from two case histories, one in Wellington, New Zealand, and one in Petrinja, Croatia, where gravels have liquefied. In both cases, the CPT occasionally overestimated liquefaction resistance in gravel layers. The advantages of using a 74 mm diameter Dynamic Cone Penetrometer (DPT) are also highlighted with companion testing.
Abstract
Although gravelly soils have been observed to liquefy in 27 earthquakes in the past 120 years, many engineers believe that gravel cannot liquefy due to its high hydraulic [...]
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Quantitative Assessment of Tip Saturation for High Quality Piezocone Testing
I. Rocchi*, L. Tonni, G. Gottardi

ISC2024.

Abstract
The research compares 2 CPTU profiles obtained with a same piezocone setup but having a different degree of saturation associated with the pore pressure measuring system. In the reference test, saturation was performed injecting 20cS silicon oil in the conduit connecting the porous stone to the pressure sensor and applying vacuum while submerged in oil for 15 minutes. The piezocone tip was then assembled with a saturated porous stone while submerged in oil. In the other test, the degree of saturation was purposely lowered by introducing air in the same conduct, whereas all other saturation steps were unchanged. The degree of saturation was compared quantitatively by measuring an analogue of the Skempton’s coefficient B, which is routinely used in laboratory testing to assess specimen saturation in a triaxial cell. The value associated with the saturation condition was measured employing a tool specifically designed for this purpose. The saturation procedures adopted were selected based on preliminary experimental activity in the laboratory, which provided target values of the pore pressure parameter corresponding to full or partial saturation. The CPTUs were performed at a test site presenting 10m clay unit followed by sand. The profiles measured were compared in terms of pore-pressure profiles, as well as the influence this had on corrected tip resistance, Soil Behaviour Type classification and mechanical properties. Additionally, a dissipation was performed for each test to compare consolidation parameters.
Abstract
The research compares 2 CPTU profiles obtained with a same piezocone setup but having a different degree of saturation associated with the pore pressure measuring system. [...]
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Calibration Chamber Testing on Tailings for Interpretation of Partially Drained CPT
M. Ghafghazi, L. Qi*, H. Zhao, W. Liu, M. Etezad, J. Sharp, M. Talesnick

ISC2024.

Abstract
The Cone Penetration Test (CPT) is the primary site investigation tool in silt-rich tailings. The permeability and compressibility range of tailings often puts the standard CPT penetration rate in the partial drainage range where the tip resistance, pore water pressure, and sleeve friction become functions of not only the state, but also drainage conditions. This makes interpretation of the state parameter, which represents liquefaction susceptibility and residual strength of tailings particularly challenging. It is not clear whether existing CPT interpretation frameworks are capable of accounting for effects of partial drainage. Developing field correlations for interpreting partially drained CPT data in tailings is hampered by spatial variability and sampling disturbance. CPT tests were performed in a calibration chamber and in the field on a gold tailings material. Dissipation tests were performed, and the pore water pressures on the cone at the u2 position were monitored. The degree of partial drainage was estimated based on the coefficient of consolidation inferred from these dissipation tests. Similarities and differences of the calibration chamber and field CPTs were discussed.
Abstract
The Cone Penetration Test (CPT) is the primary site investigation tool in silt-rich tailings. The permeability and compressibility range of tailings often puts the standard [...]
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Methodology for Determining Optimum Vibrating Wire Piezometer Pairing Relationships in VWP Monitoring Clusters
C. Meyer*

ISC2024.

Abstract
Current trends in the mining sector and specifically tailings storage facilities have seen a significant increase in monitoring frequency, instrumentation installed on site and field tests conducted. Monitoring methodologies are also shifting away from analog and towards digital electronic systems. These instruments are also being integrated with online dashboards. Owing to all these factors, the instrument that is now most commonly being installed to meet these requirements are VWP’s (Vibrating Wire Piezometers). However interpreting VWP results and deriving the phreatic surface from these are not as straight forward as initially assumed, it requires engineering judgement and a methodology to determine and verify optimum pairing of VWP clusters. Obtaining the correct phreatic surface from VWP’s is critical as this will have a direct impact on the trigger levels and TARP’s of the online dashboard. Inaccuracies in calculating the phreatic surface can lead to the triggering of incorrect levels, which may result in flawed assessments of stability. The primary approach relied on phreatic surface and hydraulic gradients from CPTu testing being compared to the phreatic surface and hydraulic gradient determined from various combinations of VWP’s in a cluster at the time of CPTu testing. In cases where no historical VWP data is available at the time of CPTu testing, a methodology was also investigated using standpipe piezometers only. Piezometric head was converted to pressure and linear regression used to determine the phreatic surface. Results from the primary approach showed that certain pairs of VWP’s yield phreatic surfaces and hydraulic gradients that match the CPTu findings. Standpipe interpretation provided a good starting point and correlates with primary identified pairs. This methodology provides a verification tool to provide confidence when selecting VWP combinations for dashboard reporting.
Abstract
Current trends in the mining sector and specifically tailings storage facilities have seen a significant increase in monitoring frequency, instrumentation installed on site [...]
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Restrictions of CPTu Based Interpretation Methods and Impact Thereof on Limit Equilibrium Modelling
J. Visagie*, E. du Plessis

ISC2024.

Abstract
There is a large reliance on piezometric cone penetration testing (CPTu) in the tailings industry to estimate strength parameters for assessing the stability of tailings storage facilities (TSFs). It is common practice to assess the post-liquefied stability of a TSF using a residual undrained shear strength ratio (USSR). In such an assessment the residual USSR is typically applied to all saturated tailings. The current methods available to analyse CPTu data, are largely based on correlations and assumptions, and therefore contain limitations. Due to the limitations of the methods, this could lead to either over- or un-conservative estimates of stability. In this study, three methods for determining liquefaction potential and residual undrained shear strength ratio (USSR) are compared, namely: Robertson (2022), Been and Jefferies (2016), and Olsen and Stark (2002). These methods differ in the way in which they apply cone resistance, sleeve friction, and dynamic pore pressure response to estimate residual USSR. Their limitations are highlighted and discussed. A hybrid method is proposed for applying the results to post-liquefaction stability analyses. The hybrid interpretation approach uses a combination of the methods to account for different ranges of effective overburden stress and to identify weaker and stronger layers in the tailings profile based on state parameter, residual USSR, and pore pressure response. This hybrid method was applied to a stability assessment of a decommissioned platinum tailings storage facility in South Africa. The results indicated that the hybrid interpretation resulted in a more realistic phreatic surface location and a more accurate failure plane than conventional interpretations.
Abstract
There is a large reliance on piezometric cone penetration testing (CPTu) in the tailings industry to estimate strength parameters for assessing the stability of tailings storage [...]
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Technical Note on Calibration for Cone Penetration Testing in Soft Soils
G. Scholey*

ISC2024.

Abstract
Even the most experienced geotechnical engineer is likely to assume that the results of cone penetration tests are unquestionably accurate, reliable and repeatable. There are, however, multiple factors, some that have nothing to do with the soil properties, that need to be carefully addressed prior to testing if the equipment is to return results that can be relied on for design purposes. In soils which are very soft or soft, cone penetration test results can be particularly sensitive to the method of calibration. A high degree of rigour to the calibration process is required, otherwise there is a risk that the results obtained could be inaccurate and adversely impact on the reliability of the interpretation of design soil strength profiles. In this technical note sources of error in cone calibration are discussed. Reference is made to ISO 22476-1 which was revised in 2022, with the addition of a defined approach to calibration. Examples are used to demonstrate the typical errors that could be introduced during calibration.
Abstract
Even the most experienced geotechnical engineer is likely to assume that the results of cone penetration tests are unquestionably accurate, reliable and repeatable. There [...]
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Portable Pressiocone System for Carrying Out CPTU+FDP (Full Displacement Pressumeter) Tests
M. Sacchetto*, G. Vinco

ISC2024.

Abstract
Geotechnical investigations in the subsoil of existing buildings have always been challenging due to limited space and difficult access. URETEK has developed a portable integrated system for simultaneously carrying out a CPT and a pressumeter test with Full Displacement Pressuremeter (FDP). The 30 kN thrust penetrometer to be used is very small. The reaction is given by two “microanchors”. The cone is a standard 10 cm2 digital memory cone (no cable), capable of measuring qc, fs, u every centimetre. Above the cone there is the FDP equipment with a rubber sheath covered by steel plates and connected, by a tube filled with water, to a device for creating pressure to inflate the sheath and measure pressure-volume curves as in a standard pressumeter test. The pressure-volume device and the depth transducer are connected to a microcomputer that is programmed to carry out CPT+FDP tests in an easy-to-use/user-friendly way.
Abstract
Geotechnical investigations in the subsoil of existing buildings have always been challenging due to limited space and difficult access. URETEK has developed a portable integrated [...]
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Finite element analysis of self-boring pressuremeter tests in clay
Y. Dong*

ISC2024.

Abstract
Self-boring pressuremeter (SBPM) tests are widely used in site investigations, due to their distinct advantage to measure the shear stress-strain-strength properties of the surounding soil with minimum disturbance. The measured pressuremeter curve can be interpreted using analytical solutions based on the long cylindrical cavity expansion theory with relatively simple constitutive models. However, SBPM tests are strongly affected by the soil behavior and details of installation procedure. In addition, the derived parameters for clays (e.g. undrained shear strength, and shear modulus) are affected by a number of state variables such as overconsolidation ratio, and stress level. In this paper, SBPM tests are investigated using finite element analysis and the MIT-S1 model, to consider complex soil behavior more realistically. SBPM tests in K0-consolidated Boston Blue Clay at different OCRs are simulated in axial symmetric and plain strain conditions, consistent with the assumptions used in analytical solutions. The derived undrained shear strength from both contraction and expansion curves are compared with theoretical values from stress-strain curves, to evaluate the reliability of the derived parameters from the SBPM tests.
Abstract
Self-boring pressuremeter (SBPM) tests are widely used in site investigations, due to their distinct advantage to measure the shear stress-strain-strength properties of the [...]
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Development of a Calibration Chamber System for Testing at High Confining Pressures
M. Haynes*, D. Reid, R. Fanni, K. Smith

ISC2024.

Abstract
Cone penetration testing with pore pressure measurement (CPTu) represents a state of practice tool to assess the in situ state parameter, strength, and liquefaction susceptibility of sandy soils and mine tailings. Many techniques for the interpretation of CPTu data are based on the results of calibration chamber test programs on sand and, more recently, mine tailings. While these efforts have led to the current methods to interpret CPTu data, two factors relevant to CPTu interpretation require consideration: (i) the available calibration chamber data is dominated by tests with consolidated mean effective stresses < 200 kPa; and (ii) tailings storage facilities are being constructed to heights such that in situ effective stresses are far higher than those of the available calibration chamber test database. While much of CPTu interpretation is carried out in a dimensionless framework, there is evidence that existing relationships between stressnormalised tip resistance and state parameter are dependent on effective stress. This stress-dependence has been attributed to a variation in shear rigidity with effective stress, which is not accounted for in many interpretation techniques. However, at high stresses, other factors such as the curvature of the critical state line in an e-log(p’) plane may contribute. To assess CPTu of sands at high stresses, a novel small-scale calibration chamber employing a miniature cone capable of testing soils consolidated to a mean effective stress up to 2,000 kPa is outlined. Test results are presented for tests carried out over a range of mean effective stresses up to 1,000 kPa.
Abstract
Cone penetration testing with pore pressure measurement (CPTu) represents a state of practice tool to assess the in situ state parameter, strength, and liquefaction susceptibility [...]
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Does CPT Reference Value Drift Really Inform CPT Correctness?
A. McConnell*, M. Chapman

ISC2024.

Abstract
The two authors’ company (IGS) is an in situ testing and sampling contractor. Approximately 40% of the company’s business is cone penetration testing (CPT). The CPT cones they use are good quality commercial units supplied by the Dutch company Geomil, with qc capacities ranging from 3MPa to 100MPa. Both compression-type and subtraction-type cones are used. IGS undertakes their own in-house calibrations on all cones, using externally calibrated load cells, and a combination of dead weights and hydraulic load application. Calibration and adjustment is undertaken on every cone on an unusually frequent basis, explained in the paper, far more frequently than current standards or manufacturer recommendations require. At each calibration, the reference readings (sometimes known as baseline readings) of each cone’s tip qc, sleeve fs, and pore pressure U sensors are noted. And the slope of the applied-load/pressure-vs-cone-readout for each of these sensors (ie accuracy) is measured and adjusted to give as close as reasonably possible 100% accurate output. All of this is recorded for each cone. Thus the authors have a database of reference reading drift that can be compared to slope adjustments (ie calibration adjustments) that have been needed to achieve the desired cone accuracy. This paper graphically reports the data for tip and sleeve of eight typical CPT cones of the day-to-day types used by the company.
Abstract
The two authors’ company (IGS) is an in situ testing and sampling contractor. Approximately 40% of the company’s business is cone penetration testing (CPT). The CPT [...]
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Importance of Calibration Laboratories in In-situ Test Methods
N. Parasie*, G. Sinjorgo, L. Vrielink, J. Peuchen

ISC2024.

Abstract
Geotechnical in-situ test methods provide valuable data for asset development, operation, and decommissioning. For confidence in test results, industry typically requires calibration and verification of in-situ test sensors to be conducted in a calibration laboratory. A calibration laboratory typically operates according to ISO/IEC 17025 (2017) ‘general requirements for the competence of testing and calibration laboratories’, or similar standard. This paper summarises observations from practice, with focus on the following challenges (1) evaluation of measurement uncertainty of key parameter values for which no standardised methods or verification materials are available, (2) validation of test methods with no backup from a formal standard published by a standardisation organisation and (3) field test site and interlaboratory comparisons within a competitive industry setting. Specific examples are presented for the (1) estimation of calibration uncertainty for sleeve friction of a subtraction-type cone penetrometer and (2) method validation for thermal conductivity of soil derived from in-situ heat flow measurements.
Abstract
Geotechnical in-situ test methods provide valuable data for asset development, operation, and decommissioning. For confidence in test results, industry typically requires [...]
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Offshore shear wave velocity measurements for the assessment of soil sampling quality
A. Deu*, A. Gens, A. Viana Da Fonseca, M. Devincenzi, D. Tarragó

ISC2024.

Abstract
Shear wave velocity Vs is a critical soil parameter for several geotechnical and geophysical engineering applications including seismic site response analysis, liquefaction risk assessment and design of shallow and deep foundations. Moreover, the comparison of shear wave velocity between laboratory and in situ measurements has become a standard acceptance criterion for the assessment of sampling quality. Offshore in situ shear wave velocity testing is considerably more challenging than onshore, due to the difficulties in the correct deployment of the instrumentation as well as of the wave source, in absence of direct visibility of the ground level below water. This paper describes the methodology employed for offshore shear wave velocities (Vs) measurements in the harbour of Barcelona in September 2022. Medusa SDMT tests were performed in sea depths ranging between 15-17 m from a jackup and employing a drill rig to penetrate the probe down to 40 m below the seafloor. The paper includes examples of recorded S-wave seismograms, analyses of Vs repeatability for the same depth measurements and Vs profiles with depth. In the same test locations, carefully prepared specimens of undisturbed samples were tested after reconsolidation to the estimated in situ stress states in stress path triaxial cells with bender elements transducers. The obtained lab shear wave velocities were compared with the in situ values obtained with the Medusa SDMT tests to assess sample quality.
Abstract
Shear wave velocity Vs is a critical soil parameter for several geotechnical and geophysical engineering applications including seismic site response analysis, liquefaction [...]
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Influence of hydrogeological conditions on estimation of undrained shear strength by CPTu tests: case study in a tropical soil
I. Rigatto*, L. Ferreira

ISC2024.

Abstract
CPTu tests have gained prominence in the geotechnical characterization of materials, registering a significant increase in their application in the Brazilian context, especially due to requirements to consider undrained resistance in analyses guided by more recent regulations. However, the interpretation of these tests often lacks a detailed and personalized approach, as they disregard specific nuances of each location. In this study, the foundation of a dam made up of tropical soil with a specific hydrogeological condition, characterized by bottom drainage with deep percolation, previously identified in other research campaigns, was evaluated. The interpretation of the CPTu test aimed to estimate the undrained resistance of the material through two different approaches: considering the dissipation tests carried out to model the insitu pore pressure according to the elevation versus a hypothetical hydrostatic condition, which could be misinterpreted in places where there is a predominance of SPT tests and insufficient geological knowledge. Multiple methodologies were evaluated to interpret undrained shear strength, including approaches that use Bq directly and that exclusively considers the laboratory characterization of a sample and the overconsolidation ratio at that point. In this case analyzed, it was observed that the change in pore pressure conditions resulted in a considerable variation in the undrained shear strength ratio, over 10% when pore pressures are considered in the equations. The results highlight the relevance of considering local hydrogeological conditions when interpreting field tests, especially for foundations of large structures.
Abstract
CPTu tests have gained prominence in the geotechnical characterization of materials, registering a significant increase in their application in the Brazilian context, especially [...]
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Engineering characterization of lacustrine soil deposits at the inner bay of Puno around Titicaca Lake
S. Laura-Huanca*

ISC2024.

Abstract
The inner bay of the city of Puno has been the subject of various investigations that seek to recover and enable floodprone areas, through strategic urban development projects (urban infrastructure) and protection works. On the other hand, the characteristics of soft soil deposits, such as those in the inner bay of Puno, represent a risk of problems with excessive settlement of the infrastructure. This study presents an engineering characterization of the lacustrine soil deposits in the inner bay of the city of Puno, around Lake Titicaca. The site lies around the Pier of Puno city at Lake Titicaca, the highest navigable lake in the world, approximately a few hundred meters in front of the National University of the Altiplano of Puno (UNAP) and a few hundred meters to the southward of the Pier of Puno city. Physical, strength, and deformation properties were determined from standard laboratory tests. The material studied corresponds to the shallow layers of the study area, corresponding to sedimentary soils of the lacustrine units and fluvial-alluvial deposits of the inner bay of Puno. These lacustrine soils are classified as highly plastic silts and organic clays (MH and OH). The results show the significant influence of the quality of soil samples, due to the sampling method and storage time, on consolidation and resistance parameters. Finally, this study provides valuable insights into the influence of sample quality on consolidation parameters and shear strength of the lacustrine soils in the inner bay of Puno city around Titicaca Lake.
Abstract
The inner bay of the city of Puno has been the subject of various investigations that seek to recover and enable floodprone areas, through strategic urban development projects [...]
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Assessing shear wave velocity profile uncertainty using multiple sCPT interpretation and processing methods
L. Wotherspoon*, A. Stolte, B. Cox

ISC2024.

Abstract
This paper quantifies the influence of seismic Cone Penetration Test (sCPT) interpretation and processing methods on shear wave velocity (VS) profile uncertainty using data from 20 sites in Christchurch, New Zealand. The near-surface soil profiles varied across the sites, both in terms of the soils that were present and the profile layering characteristics, reflecting the depositional environment that is influenced by alluvial and coastal processes. The same experimental setup was used at each site, consisting of a dual receiver sCPT cone and a hammer source method at a consistent horizontal offset distance. Three commonly used shear wave arrival time picking methods and the cross-correlation method were used to define arrival times and time intervals between testing depths for each site. The pseudo-interval, true-interval and slope-based processing methods were used with these arrival times and time intervals to develop 11 VS profiles for each site. Alongside this, a ray tracing inversion method provided an additional VS profile at each site. The uncertainty in the VS profiles that were developed at each site are presented, highlighting the variability resulting from different processing and picking methods. Results across sites are combined to provide a representation of the uncertainty across all methods and the differences in the uncertainty across the various processing methods.
Abstract
This paper quantifies the influence of seismic Cone Penetration Test (sCPT) interpretation and processing methods on shear wave velocity (VS) profile uncertainty using data [...]
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Uniaxial Compressive Strength versus Shear Seismic Wave Velocity
M. Cabrera*, M. Combarros

ISC2024.

Abstract
Worldwide, geotechnical engineers frequently use the Uniaxial compression test for soils and rocks as a basis for determining the strength of the materials, despite the fact that test results are subject to a wide range of uncertainties (drilling technique, care during transport and stockage, sample preparation, and sample representativity of the soil or rock layer). The process of geophysical site research uses Refraction Seismic Survey and Passive Tomography to determine the shear and compression seismic wave velocities for various rock and soil layers under the surface. The study examines the correlation between the outcomes of the Uniaxial Compression Tests and the shear seismic wave velocity measured at a 400 ha location in the Atacama Desert (Chile), which was intended to host 84 km of linear solar panels. A robust survey of the axial compression value was determined at a vast site spanning 400 hectares by integrating Uniaxial compression tests, Brazilian test, Shear, and Compression seismic wave velocity.
Abstract
Worldwide, geotechnical engineers frequently use the Uniaxial compression test for soils and rocks as a basis for determining the strength of the materials, despite the fact [...]
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Seismic P-, SH- and SV-Wave Cross-Hole Testing Using Direct-Push Technology for the Determination of Geotechnical Parameters
T. Fechner*, U. Koedel, S. Mackens-Siemes

ISC2024.

Abstract
Seismic surveys are often carried out between two or more pre-installed boreholes to assess unknown geological situation in the subsurface with high resolution. However, the cost of installing boreholes is often a budgetary constraint. Therefore, the direct-push technology, where rods are pushed into the subsurface, seems to be a more suitable tool and by incorporating seismic sources and receivers into the push rods, geophysical methods can become more flexible and adaptable, especially for larger areas of investigation or sites in harsh environments. In this paper, we present field results using such a direct-push seismic system as a cost-effective alternative to standard borehole-based investigation techniques. For both techniques complete cross-hole datasets of P, SV and SH waves were acquired at two different test sites (1) between direct-push boreholes and (2) between PVC cased boreholes. The in-situ profiles of the paired shear wave velocity profiles (SH and SV) were used to evaluate the stress history of the soils by deriving the over-consolidation difference (OCD). Many geotechnical parameters are influenced by the soil stress history, such as deformation properties and soil stiffness, but in the calculation of geotechnical parameters, such as the lateral stress state (K0), consolidation coefficient and liquefaction response the OCR also plays an important role. The tests also showed that direct-push based techniques make even seismic methods more flexible as test positions can be easily adapted and changed according to the results, local conditions or client requirements.
Abstract
Seismic surveys are often carried out between two or more pre-installed boreholes to assess unknown geological situation in the subsurface with high resolution. However, the [...]
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Development of a framework for automatic quantification of uncertainty in seismic cone penetration testing
R. Buckley, T. Zheng*, E. Febrianto

ISC2024.

Abstract
Accurate quantification of the shear wave velocity, Vs, of geo-materials is an important consideration in geotechnical design. Seismic Cone Penetration Testing (SCPT) measures shear wave travel times from a source to in situ receivers along assumed travel paths to calculate Vs. Despite complexities and uncertainties associated with obtaining Vs, results are often reported to designers as a single deterministic profile without an intuitive measure of uncertainty that can be incorporated into the design process. A rigorous workflow to rapidly obtain uncertainty-quantified profiles from SCPT using a Bayesian inversion approach is developed. While similar approaches have been documented, this inversion approach explicitly considers sources of measurement error which are generally neglected (i.e., assumed to be low) in order to deliver more realistic probability distributions of true Vs and improve robustness against imperfect data. Such errors can remain undetected when using traditional approaches, despite potentially leading to inaccuracy. Additionally, an outlier detection framework is incorporated into the workflow to improve accuracy. The workflow is demonstrated by application to a large database of SCPT data. The results show significant improvement over existing methods in terms of robustness and validity, and therefore that the workflow is a valuable tool for practical analyses. Further, they provide crucial insight into the prevalence and magnitude of key errors which are traditionally present but undetected.
Abstract
Accurate quantification of the shear wave velocity, Vs, of geo-materials is an important consideration in geotechnical design. Seismic Cone Penetration Testing (SCPT) measures [...]
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Multi-method in situ geophysical testing in a high porosity chalk mass
R. Buckley*, N. Shinde

ISC2024.

Abstract
Chalk is a silt-sized soft biomicrite rock often encountered as a low to medium density, high porosity, structured material within a fractured mass. In recent years, there has been increased interest in the behaviour of chalk and the development of new design procedures for pile foundation installation design, motivated by several large-scale onshore and offshore infrastructure projects. Recent modelling has demonstrated the importance of accurately characterising the operational stiffness of the chalk mass. While several methods exist to measure the chalk’s stiffness in situ, they are often subject to significant scatter, with no guidance available to the end user on interpretation or on which method should be used as a baseline. A new programme of multi-method in situ geophysical testing in chalk at a well-characterised onshore test site in Southern England is described that forms part of a wider research project. The chalk deposit is shown to be relatively uniform with depth which provides a unique opportunity to apply multiple methods and interpretations without the influence of significant layering. The experimental programme is described and the interpretation and selected results of downhole geophysical tests at depths up to 40m are presented. The chalk’s remarkably high shear stiffnesses are shown to be highly repeatable and consistent when rigorous test execution and analysis is applied
Abstract
Chalk is a silt-sized soft biomicrite rock often encountered as a low to medium density, high porosity, structured material within a fractured mass. In recent years, there [...]
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A case study addressing the development of a novel marine seismic cone penetration testing system.
D. Donaghy*, S. Whyte, H. Christian

ISC2024.

Abstract
Within the offshore wind sector, following the conclusions of the Pile Soil Analysis (PISA) Project increased emphasis has been placed on the acquisition of in-situ ðºðºðððððð data, to corroborate laboratory-based measurements, to allow for foundation weight optimization. This requirement for higher fidelity data at all wind turbine locations is coupled with the increased requirement to acquire data in shorter periods to meet ambitious development schedules for offshore wind farms. The development of a deep push seabed SCPT which can be deployed fully autonomously is considered to address this challenge facing the offshore wind industry. Recognising that within the current standards there is a shortfall on what is considered as accurate and reliable data with regards to having confidence in the shear wave velocity (ð£ð£ð ð ) measurements obtained offshore, there is a requirement for discussion within the industry; clients, designers and contractors, on how to provide improved set-ups, acquisition and interpretation methods in order to increase the confidence in the ð£ð£ð ð data acquired. The case study described within this paper, initiated by such dialog, presents the specification, construction, testing and utilisation of a dual array non-drilling mode seismic cone penetration test (SCPT) device and seismic source to provide demonstrable reliability and accuracy in acquisition and interpretation of in-situ ð£ð£ð ð measurements. Within this context, the paper describes; the engineering considerations and optimisation of a novel device intended for deployment from a new generation of robotic vessel; application and limitations of the set-up during trials and offshore operations; commentary on the in-situ data including challenges encountered during interpretation and comparison with existing data acquired at the same location, established correlations and site-specific correlations.
Abstract
Within the offshore wind sector, following the conclusions of the Pile Soil Analysis (PISA) Project increased emphasis has been placed on the acquisition of in-situ ðºðºðððððð [...]
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