JOURNALS

Documents published in Scipedia

• Multiscale approach for the analysis of composite connections and stiffeners in marine shell structures

  F. Turon, F. Otero, X. Martinez

  marine2023.

  
  

  • 1
  •  read

• Analysis of composite beams using reduced order modeling

  R. Rubio, A. Ferrer, J. HERNÁNDEZ ORTEGA, X. Martinez

  Materiales Compuestos (Online first).

  
  

  Abstract

  Beam-like components help to provide structural integrity in a wide range of applications. Initially made of alloys or natural materials such as wood, today’s technologies like pultrusion make possible the manufacturing of such components with composite materials providing good quality products with high performance to weight ratio. The anisotropic nature of composite materials, though, poses a challenging framework when numerically simulating them. This work presents the integration in standard Finite Element (FE) packages of a machine learning methodology that naturally captures the behaviour of composite materials: the multiscale method for periodic structures using domain decomposition and ECM-hyper reduction. The method provides a special type of finite element that can be assembled using FE libraries. However, the kinematics of this element may be described by more Degrees of Freedom (DoF) per node than most standard FE packages consider, hence implementing it is a non-trivial task. The strategy presented here tries to tackle the limitation by means of static condensation followed by a regression procedure. Periodic boundary conditions are employed for the extra DoFs while the regression consists in a polynomial on the logarithmic space. This paper focuses on the performance of the integrated beam element through the analysis of a pultruded omega profile whose anisotropy requires the use of complex models to accurately capture its mechanical behaviour. The agreement between the results obtained with the proposed model and those given by more complex formulations validates the methodology and enables its use in regular FE codes to characterize complex composite beam structures.

  Abstract
  Beam-like components help to provide structural integrity in a wide range of applications. Initially made of alloys or natural materials such as wood, today’s technologies [...]

  • 0
  •  read

• FRP Offshore Structure Connections Optimization and Validation by Classification Society standards

  A. Borrás, F. Otero, X. Martinez

  marine2023.

  
  

  Abstract

  This paper discusses the use of composite materials in the design process of a horizontal bracing to column connection of an offshore semi-submersible platform to support two wind turbines. The geometry of the connection was optimized to improve the performance and reliability of the connection, columns and bracing tubes. These offshore foundations usually deal with massive structural tubes, and they are used to fit a huge amount of stiffeners. This paper will show how using some horizontal stiffeners combined with their intersection with horizontal bracings tubes, can improve drastically the behavior of the connection. A comparison between conventional materials (steel) and advanced materials (E-glass fibres and epoxy matrix) was performed and it was demonstrated how the use of composite materials makes necessary to modify the connection geometry and configuration to obtain an equivalent performance. This is due to the very different stiffness behavior shown by composites and steel. Therefore, the design of an offshore connection must be approached differently according to the used material. The composite laminate layout design process was also made. The material was evaluated using a Bureau Veritas normative note specifically applicable to composite ship hulls, but adapted to the needs of the materials used in this design, in terms of raw material requirements. The design process of a laminate panel of the connection is shown using the above mentioned standard. All data and results shown here were harvested within the scope of the European research project Fibregy (EU Horizon 2020, Ref. 952966).

  Abstract
  This paper discusses the use of composite materials in the design process of a horizontal bracing to column connection of an offshore semi-submersible platform to support [...]

  • 2
  •  read

• Combination of 3D solid finite elements with rotation-free beam elements for non-linear analysis of fiber reinforced polymer rebars

  F. Zarate, T. Villette, X. Martinez, F. Rastellini Canela, D. Cendón, C. Andrade, E. Oñate

  Rev. int. métodos numér. cálc. diseño ing. (2023). Vol. 39, (2), 12

  
  

  Abstract

  We present a combination of three dimensional (3D) solid elements and rotation-free beam elements for non-linear analysis of fiber-reinforced polymer (FRP) of rebars. The matrix material is modelled by 3D solid elements while the fibers are modelled with rotation-free beam elements. The absence of rotation variables in the beam elements allows the straightforward coupling of 3D solid and beam elements using a formulation with displacement nodal degrees of freedom only. Both solid and beam elements are formulated in an updated Lagrangian description. The behavior of the matrix and the fiber material are modelled with an elastic-damage model. The efficiency and accuracy of the combined 3D-beam element formulation are verified in examples of application to the analysis of FRP rebars up to fracture in axial, bending and shear tests for which experimental results are available.

  Abstract
  We present a combination of three dimensional (3D) solid elements and rotation-free beam elements for non-linear analysis of fiber-reinforced polymer (FRP) of rebars. The [...]

  • 15
  •  read

• FIBRE4YARDS: Fibre Composite Manufacturing Technologies for the Automation and Modular Construction in Shipyards

  X. Martinez, D. Sá, J. Silva, S. Alvarez-Buylla

  Materiales Compuestos (2022). Vol. 06 - AEMAC en PROYECTOS EUROPEOS (2022), (Num. 2 - Monográfico Proyectos Europeos (2)), 185

  
  

  Abstract

  FIBRE4YARDS project aims to improve the competitiveness of small and medium European shipyards working with Fibre Reinforced Polymers (FRP). To this extent, the project expects to bring new automated cost-efficient production technologies to the shipyard (adaptive moulds, ATP/AFP, 3D printing, curved pultrusion profiles, hot stamping, innovative composite connections) from other competitive industrial sectors, and to transfer, adapt and combine them to improve FRP shipyards’ production and maintenance. In order to incorporate all new manufacturing technologies into the ship design, FIBRE4YARDS will develop new advanced computational tools and numerical formulations specially developed to characterize the new procedures. Ship design will also take into account the environmental impact of the materials and manufacturing technologies used, based on a Life Cycle Assessment. All new production procedures will be implemented in a new Shipyard 4.0 environment which, among other features, will be interconnected thanks to IoT technologies, and will be continuously monitored to ensure high quality processes using a digital twin of the shipyard. Special care will be taken to ensure that all technologies proposed by FIBRE4YARDS project comply with the actual standards, writing new guidelines when those do not exist, and that can be implemented in European Shipyards smoothly and straightforward. With the proposed approach, shipyards will improve their production capacity and the quality of the ships manufactured, making them more safe and efficient.

  Abstract
  FIBRE4YARDS project aims to improve the competitiveness of small and medium European shipyards working with Fibre Reinforced Polymers (FRP). To this extent, the project expects [...]

  • 49
  •  read

• BEDYN: development of a methodology to characterize the behaviour of composite structures under dynamic loading

  E. Gonzalez, P. Villarroel, J. Guerrero, S. Medina, P. Maimi, J. Artero-Guerrero, A. Cimadevilla, M. Gascons, J. González, E. Blanpre, V. Jacques

  Materiales Compuestos (2022). Vol. 06 - AEMAC en PROYECTOS EUROPEOS (2022), (Num. 2 - Monográfico Proyectos Europeos (2)), 184

  
  

  Abstract

  The methodology of design of polymer-based composite structures under static loadings, and even fatigue loads, is quite mature and well stablished. However, for intermediate and high dynamic loading conditions, the methods are still under development and often limited to academic research levels, without any type of standardization. It is crucial to understand how the materials used in the aerospace sector behave under dynamic loadings. Composite materials may exhibit strain rate effects and the analysis tools based on static formulations could be far away from the actual material and structural response, therefore robust and industrial dedicated dynamic tests, analysis and modelling methods are then necessary to design and certify composite airframe structures. This is what the proposed project will deal with. The aim of BEDYN project is to address a methodology to properly characterize the dynamic behaviour up to rupture of thermoset polymer-based composite structures submitted to dynamic loading. BEDYN is a European granted Clean Sky 2 Joint Undertaking (JU). 

  Abstract
  The methodology of design of polymer-based composite structures under static loadings, and even fatigue loads, is quite mature and well stablished. However, for intermediate [...]

  • 1
  •  read

• New advanced manufacturing process for rear fuselage sections of highly integrated aerospace structures

  G. Nuñez-Márquez, P. Tabarés-Fernández, M. Mora-Mendías

  Materiales Compuestos (2022). Vol. 06 - AEMAC en PROYECTOS EUROPEOS (2022), (Num. 2 - Monográfico Proyectos Europeos (2)), 183

  
  

  Abstract

  CS2-LPA-IADP-WP1.2.5. Advanced Rear End Manufacturing is an European project, inside of the CleanSky2 research program of the European Union Horizon 2020 (Grant Agreement nº 945583). This work package focuses on design, manufacturing and testing of new technologies for the manufacturing of aeronautical structures, integrating different elements, at the rear end of an aircraft. The work presented here shows the manufacturing process developed to obtain a full-scale demonstrator of a rear end section of the fuselage in prepreg carbon fiber composite material, integrating stiffeners, contour frames and skin in one-shot. The omega section stiffeners are made by automatic lay-up and forming, integrate them fresh into the demonstrator. The contour frames are also automatically lay-up and formed, carrying out a semi-curing cycle (for which a manufacturing test campaign has been necessary and different curing degree studies). The integration of these semi-cured frames in the demonstrator combines the advantages of a cobonded integration (without rivets) and the simplification of the tools respect to fresh elementals, since the final thickness has already been consolidated. The automatic lay-up of the skin is carried out on a tool where the fresh stiffeners and the semi-cured frames are located. Finally, the curing cyle is done in the autoclave, obtaining the full-scale highly integrated fuselage demonstrator. All the technologies developed in this demonstrator allow automation within an industrial environment with high production rates. 

  Abstract
  CS2-LPA-IADP-WP1.2.5. Advanced Rear End Manufacturing is an European project, inside of the CleanSky2 research program of the European Union Horizon 2020 (Grant Agreement [...]

  • 3
  •  read

• Design, production and characterization of high performance 3R composites based on dynamic chemistry for the aerospace industry

  N. Markaide, A. Luzuriaga, V. Gayraud, A. Salaberria, M. Rodríguez, M. Walls

  Materiales Compuestos (2022). Vol. 06 - AEMAC en PROYECTOS EUROPEOS (2022), (Num. 2 - Monográfico Proyectos Europeos (2)), 182

  
  

  Abstract

  The objective of the AIRPOXY project is to reduce production and maintenance, repair & operating (MRO) costs of composite parts in aeronautics, by introducing a new family of enhanced thermoset composites that preserve all the advantages of conventional thermosets, while show unprecedented new features such as Re-processability, Repairability and Recyclability. This new generation of composites, called 3R composites, are obtained using dynamic hardeners which create reversible crosslinks in the cured epoxy resin. Once the 3R composite has been produced, the dynamic chemical bonds in the cured resin can be reshuffled under determined external stimulus, such as temperature or exposure to a specific chemical agent. The study describes the development of a first version of 3R composite that meets the requirements of the aeronautical sector. Firstly the resin has been formulated, then the composite laminates have been produced by Resin Transfer Moulding (RTM) and finally their dynamic and mechanical properties have been studied.

  Abstract
  The objective of the AIRPOXY project is to reduce production and maintenance, repair & operating (MRO) costs of composite parts in aeronautics, by introducing a new family [...]

  • 10
  •  read

• Design and manufacture of modular molds for the development of trains composite structures

  M. Rodríguez, R. Lecouche, M. Bermúdez, M. Domingo

  Materiales Compuestos (2022). Vol. 06 - AEMAC en PROYECTOS EUROPEOS (2022), (Num. 2 - Monográfico Proyectos Europeos (2)), 181

  
  

  Abstract

  The success of the European rail system requires cost-efficient passenger trains with high capability and reliability. The development of these high demanding trains involves a concerted effort in improving a comprehensive range of elements. CARBODIN contributes to this effort by combining the research effort along with the future CFM- IP1-01-2019 and the ongoing CFM-IP1-01-2017 projects to manufacture car body shell parts, doors and to improve the interior design of passenger trains. CARBODIN improves car body shell manufacture by exploring the possibilities offered by composite materials. To this end, CARBODIN advocates for a modular tooling to manufacture a wide range of parts of varying size, leaded by EURECAT. In addition, the proposed process combines different production techniques, automation concepts, introduction of co-cured and co-bonded composite parts and multi-material integrated joints and inserts. Besides, predictive maintenance is reinforced by testing intelligent sensor nodes. Composite materials are also the core idea for cost-efficient doors with reduced LCC. The creation of modular tooling combined with 3D technology is enabling the production of lighter doors with enhanced thermal and acoustic properties in the door and its vicinity. 

  Abstract
  The success of the European rail system requires cost-efficient passenger trains with high capability and reliability. The development of these high demanding trains involves [...]

  • 0
  •  read

• Lightweight single axle running gear frame

  E. Guerra, F. García, M. Cerdeira, J. Fernández, V. Meroño

  Materiales Compuestos (2022). Vol. 06 - AEMAC en PROYECTOS EUROPEOS (2022), (Num. 2 - Monográfico Proyectos Europeos (2)), 180

  
  

  Abstract

  The railway industry seeks to increase the capacity of the railway system, providing flexibility to align capacity and demand, increasing availability, reliability and energy efficiency by reducing the life cycle cost (LCC), improving passenger comfort and increasing the attractiveness of rail transport. One of the lines of action to tackle the aforementioned challenges is the introduction of new lighter bodies and/or running gear structures, as both of these are among the heaviest components of the train. The potential weight savings (approximately 30 % and 50 %, respectively), and the use of new materials and processes in structures will result in reduced energy consumption, lower inertias, reduced track wear, and increased capacity to carry higher payloads. This article will present the development of a carbon fiber single axle running gear frame including design, calculation and testing, achieving a 50% reduction in weight while maintaining the performance of current steel structures. This project is within the Shift2Rail initiative, it is part of PIVOT and PIVOT2 Project. It has received funding from the European Union's Horizon 2020 program under grant agreements 777629 and 881807.

  Abstract
  The railway industry seeks to increase the capacity of the railway system, providing flexibility to align capacity and demand, increasing availability, reliability and energy [...]

  • 2
  •  read

Articles (Documents not available in Scipedia)

• A numerical procedure simulating RC structures reinforced with FRP using the serial/parallel mixing theory

  X Martinez, S Oller, F Rastellini, AH Barbat

  Computers & Structures 86 (15), 1604-1618, 2008