COMPLAS 2021 is the 16th conference of the COMPLAS Series.
The COMPLAS conferences started in 1987 and since then have become established events in the field of computational plasticity and related topics. The first fifteen conferences in the COMPLAS series were all held in the city of Barcelona (Spain) and were very successful from the scientific, engineering and social points of view. We intend to make the 16th edition of the conferenceanother successful edition of the COMPLAS meetings.
The objectives of COMPLAS 2021 are to address both the theoretical bases for the solution of nonlinear solid mechanics problems, involving plasticity and other material nonlinearities, and the numerical algorithms necessary for efficient and robust computer implementation. COMPLAS 2021 aims to act as a forum for practitioners in the nonlinear structural mechanics field to discuss recent advances and identify future research directions.
Scope
COMPLAS 2021 is the 16th conference of the COMPLAS Series.
The minerals processing and aggregate industry have relied on steady-state
population and mass balance simulators for decades. However, accurately modeling new
processes remains a critical challenge that hinders innovation and decision-making in the
industry. In recent years, time-dynamic simulators have been developed, which offer
more accurate predictions of process variability and performance, as well as the ability
to introduce regulators and control algorithms. Yet, these still require simplified process
models of each unit in the system. The development of high-performance discrete element
method (DEM) solvers with advanced particle physics models presents a new opportunity
to model complete comminution and classification processes.
In this paper, we discuss the potential, challenges, and current limitations of using
DEM for advanced dynamic process and equipment evaluation, exemplified by a coarse
comminution crushing and screening case. We demonstrate the methodology using a
GPU polyhedral DEM implementation with a boundary-volume hierarchy (BVH) collision
search algorithm. The results show that the scale of a full-scale two-stage crushing process
is possible to simulate. The transition from algebraic process models to DEM would make
a significant advancement, bridging the current gap between overly simplified generalized
process models and specific equipment design. This approach offers exciting opportunities
for the mineral processing and aggregate industry to develop more innovative and efficient
circuits.
Abstract The minerals processing and aggregate industry have relied on steady-state
population and mass balance simulators for decades. However, accurately modeling new
processes remains [...]
Debris flows overriding steep valleys can cause a significant decrease in bed friction resistance due to undrained excess pore water pressure, leading to an exponential increase in both destructiveness and volume. This study develops a two-phase numerical model based on Smoothed Particle Hydrodynamics to simulate the progressive entrainment behavior of debris flow accurately. The fluid and bed-sediment materials are modeled using the non-Newtonian Bingham-type Herschel-Bulkley-Papanastasiou (HBP) constitutive model. The mass erosion behavior of debris flow is achieved and augmented by incorporating the Drucker-Prager (DP) softening model, which accounts for variations in the pore water pressure ratio across different saturation states. A straightforward phase-change approach is implemented according to the mutation of effective viscosity to prevent any minute displacements of viscoplastic materials when subjected to steep inclinations. The multi-phase model has been compared with the large scale flume experiments conducted by the United States Geological Survey. The 3-D numerical results obtained from the rigid bed, dry and wet erodible bed exhibit a good agreement with the experimental data, encompassing flow momentum feedback and erosion patterns. This paper initially attempts to simulate the entrainment of multiple phases in a steep valley by incorporating viscoplastic flow.
Abstract Debris flows overriding steep valleys can cause a significant decrease in bed friction resistance due to undrained excess pore water pressure, leading to an exponential increase [...]
Particle methods such as the SPH and MPS methods have problems because it is difficult to treat curved bottom surfaces such as seabed surfaces accurately. In this study, regarding this problem, the curved bottom surfaces’ treatments have been improved using a coordinate transformation using the high-order second derivative model called SPH(2). Although the theory for the coordinate transformation was established in the MPS method, its accuracy did not give the desired accuracy because of the numerical errors of the second derivative models. Therefore, the numerical errors in these coordinate transformations were overcome by applying the second derivative model of SPH(2) to the coordinate transformation formulas. The superiority and validity of the proposed coordinate transformation using SPH(2) are demonstrated through validation examples such as the hydrostatic pressure and dam-break problems.
Abstract Particle methods such as the SPH and MPS methods have problems because it is difficult to treat curved bottom surfaces such as seabed surfaces accurately. In this study, regarding [...]
V. Singer, K. Sautter, A. Larese, R. Wüchner, K. Bletzinger
particles2023.
Abstract
In recent years, the intensity and frequency of natural hazards such as landslides, debris flow and avalanches have increased significantly due to climate change and global warming. These catastrophic events are responsible for numerous destructions of infrastructures with high economic losses and, even worse, often claim human lives. Therefore, in addition to the prediction, the design and installation of protective structures are of tremendous importance. Due to its hybrid approach of an Eulerian background grid in combination with Lagrangian moving material points, the Material Point Method (MPM) is particularly suited to capture the flow process of those mass movement hazards. For the numerical simulation of protective structures, however, other numerical methods are often preferable. Considering highly flexible structures, which are often utilized due to their high energy absorption capacity classical Finite Element Method (FEM) is best suited to model cable, beam, and membrane elements, while a retaining wall consisting of a few discrete blocks may be preferable modeled by Discrete Element Method (DEM). Therefore, we are proposing partitioned coupling approaches to combine the advantages of different numerical methods so that the protective structures can be appropriately designed to withstand the impact of those mass movement hazards.
Abstract In recent years, the intensity and frequency of natural hazards such as landslides, debris flow and avalanches have increased significantly due to climate change and global [...]
In recent years, significant advancements in computational efficiency have enabled the application of advanced numerical models to solve boundary value problems (BVPs) in geotechnics, including those related to large-displacement problems. However, challenging problems, such as those involving open-ended piles (OEs) in soft rocks, require specialized approaches due to material and geometrical non linearities combined to the large deformation soil-structure interaction. This paper presents a comparison of two approaches for modeling OE pile installation in soft rocks. The first approach employs the Discrete Element Method (DEM), which represents the rock as separate particles bonded together, and introduces a new contact model for highly porous rocks. The second approach uses the Geotechnical Particle Finite Element Method (GPFEM) and investigates the coupled hydromechanical effects during pile installation using a robust and mesh-independent implementation of an elastic-plastic constitutive model at large strains. The DEM approach explores the micromechanical features of pile plugging and unveils the mechanisms behind radial stress distributions inside and outside the plug. The study highlights the strengths and limitations of each modeling approach, providing insights into the behavior of OE piles in soft rocks.
Abstract In recent years, significant advancements in computational efficiency have enabled the application of advanced numerical models to solve boundary value problems (BVPs) in [...]
D. Mohapatra, M. SARESMA, J. Virtalaso, W. Solowski
particles2023.
Abstract
This paper shows a numerical replication of a laboratory-scale free fall cone penetrometer test of marine clay. The numerical simulation involves large deformations and considers the destructuration of clay, strain rate effects, and non-linear material behaviour. The numerical simulation well replicates the laboratory experiment captured on a high-speed camera. The penetration process is replicated accurately in time, and the depth of the penetration corresponds to that obtained in an experiment. The simulation results indicate that the numerical framework implemented in Uintah software, consisting of an advanced soil model and the Generalized Interpolation Material Point Method, is well-suited for replication of the dynamic penetration process in soft and sensitive marine clay.
Abstract This paper shows a numerical replication of a laboratory-scale free fall cone penetrometer test of marine clay. The numerical simulation involves large deformations and considers [...]
Geohazards such as rockfall, catastrophic landslides, and debris flow pose a significant risk due to the rapid movement of the vast amount of granular material carrying tremendous destructive potential and energy. Experimental and numerical studies on channelized flumes have been prevalent in analyzing the kinematics and dynamics of the flow and their interaction with various mitigation measures along the projected flow path. Continuum, discontinuum, and hybrid numerical methods have been successfully employed in the past to comprehend the complex material behaviour of granular mass flows. Although the numerical schemes within a continuum setting offer some insights into critical factors like flow velocity, flow depth, runout distance, etc., the granular interaction within the particle ensemble and the impact force on the barrier system for a better estimate of the force-transmission paths cannot be accounted for. The present study employs the Discrete Element Method to investigate the underlying physics of the micromechanical interaction of the granular assembly with the rigid barrier. Although past studies have explored granular flow-like events within a discrete setting, such studies did not incorporate particle morphology. This paper explores the effect of particle shape on kinematics and impact dynamics against a rigid obstacle. First, the numerical results have been benchmarked against the experimental studies for conventional spherical particles, and then we explore the effect of particle morphology. The present findings indicate that the particle shape significantly influences the flow kinematics and leads to a reduction in impact force on the barrier due to the higher angularity of particles with different morphological features than spherical particles, generally considered in the existing literature. A more significant implication of this study is to better understand and design mitigation measures against geohazards.
Abstract Geohazards such as rockfall, catastrophic landslides, and debris flow pose a significant risk due to the rapid movement of the vast amount of granular material carrying tremendous [...]
In the present paper, contact heat transfer on a batch-operated single circular floor of a multiple hearth furnace is numerically examined using the Discrete Element Method (DEM). The particles are agitated on the floor by a single rabble arm equipped with mixing blades. Two different rabble arm configurations are studied, a rabble arm with three blades covering just the area from the centre of the floor to the wall enclosing the circular floor, and a rabble arm with six blades, which covers the whole diameter of the floor. The floor temperature is set to 100°C, and the initial particle temperature is 20°C. Spherical particles made of aluminium and polyoxymethylene (POM) with two particle diameters (10 and 20 mm) are examined. Blade angle inclination is varied, namely, 0°, 45° and 90°. The major results are that for POM spheres the major mechanism dominating contact heat transfer is the gas layer in the vicinity of the contact point particle-floor, whereas for aluminium the heat transfer through the direct contact point of floor and particle is of equal importance as the heat transfer through the gas layer. For the first configuration with three blades, a larger blade angle leads to lower heat up rates, while the second configuration with six blades, increases the heating rate for larger blade angles.
Abstract In the present paper, contact heat transfer on a batch-operated single circular floor of a multiple hearth furnace is numerically examined using the Discrete Element Method [...]
Y. Uematsu, K. Hirata, F. Miyasaka, T. Kitamura, T. Kikugawa
particles2023.
Abstract
The bonded magnet, which is formed by mixing magnet materials such as neodymium-based and ferrite-based materials with resin, has the characteristic of being able to be formed into small and complex shapes due to the resin being the binding material. It is used in small motors embedded in hard disk drives and motors for home appliances. The major methods for forming bonded magnets are compression molding and injection molding. In this study, injection molding is selected, which can easily apply to complex shape compared to compression molding. However, injection molding has the disadvantage of variability in density and magnetic properties of the molded products. This is due to the difficulty in observing the material flow, as the molding process progresses inside the mold and multiple processes occur simultaneously such as injection, compression, magnetization, and curing. Therefore, determining the optimal molding parameters for injection molding of bonded magnets requires numerous experimental trials. Based on the above, it is believed that predicting the behavior of resin inside the mold during the molding process using numerical simulation can provide guidelines for determining the optimal molding parameters. The authors have previously proposed a coupled analysis method of "fluid analysis and temperature analysis using MPS (Moving Particle Simulation) method, and magnetic field analysis using magnetic moment method." The objective of this study is to assess the solidification process of resin on the mold surface, utilizing a rectangular-shaped mold model.
Abstract The bonded magnet, which is formed by mixing magnet materials such as neodymium-based and ferrite-based materials with resin, has the characteristic of being able to be formed [...]