Search results for "micro-mechanic"
showing 10 items of 16 documents
A HYBRID VEM/BEM NUMERICAL TECHNIQUE FOR SIMULATING DAMAGE IN COMPOSITE MATERIALS
2021
Composite materials are nowadays widely used in the aerospace sector both for primary and secondary structures for their high mechanical properties and the ability to model them according to project needs. Therefore, accurately predicting material behaviour when subjected to operating loads is extremely important in making the design process more efficient. For this purpose, computational approaches based on continuum damage mechanics have been largely used to study the progressive loss of material integrity due to the propagation and coalescence of microscopic defects. In this contribution, a recently developed hybrid computational technique, which combines the Virtual Element Method (VEM)…
Coupling BEM and VEM for the Analysis of Composite Materials with Damage
2021
Numerical tools which are able to predict and explain the initiation and propagation of damage at the microscopic level in heterogeneous materials are of high interest for the analysis and design of modern materials. In this contribution, we report the application of a recently developed numerical scheme based on the coupling between the Virtual Element Method (VEM) and the Boundary Element Method (BEM) within the framework of continuum damage mechanics (CDM) to analyze the progressive loss of material integrity in heterogeneous materials with complex microstructures. VEM is a novel numerical technique that, allowing the use of general polygonal mesh elements, assures conspicuous simplific…
A 3D multi-physics boundary element computational framework for polycrystalline materials micro-mechanics
2021
A recently developed novel three-dimensional (3D) computational framework for the analysis of polycrystalline materials at the grain scale is described in this lecture. The framework is based on the employment of: i) 3D Laguerre-Voronoi tessellations for the representation of the micro-morphology of polycrystalline materials; ii) boundary integral equations for the representation of the mechanics of the individual grains; iii) suitable cohesive traction-separation laws for the representation of the multi-physics behavior of the interfaces (either inter-granular or trans-granular) within the aggregate, which are the seat of damage initiation and evolution processes, up to complete decohesion…
A hybrid virtual–boundary element formulation for heterogeneous materials
2021
Abstract In this work, a hybrid formulation based on the conjoined use of the recently developed Virtual Element Method (VEM) and the Boundary Element Method (BEM) is proposed for the effective computational analysis of multi-region domains, representative of heterogeneous materials. VEM has been recently developed as a generalisation of the Finite Element Method (FEM) and it allows the straightforward employment of elements of general polygonal shape, maintaining a high level of accuracy. For its inherent features, it allows the use of meshes of general topology, including non-convex elements. On the other hand, BEM is an effective technique for the numerical solution of sets of boundary i…
Micro damage and cracking in fibre reinforced composites by a novel hybrid numerical technique
2020
Article number 0033974 AIP Incluida en Conference Proceedings 2309 The prediction of failure mechanisms in fibre-reinforced composite materials is of great importance for the design of composite engineering applications. With the aim of providing a tool able to predict and explain the initiation and propagation of damage in unidirectional fiber reinforced composites, in this contribution we develop a micromechanical numerical model based on a novel hybrid approach coupling the virtual element method (VEM) and the boundary element method (BEM). The BEM is a popular numerical technique, efficient and accurate, which has been successfully applied to interfacial fracture mechanics problems of f…
Influence of the anisotropy of sisal fibers on the mechanical properties of high performance unidirectional biocomposite lamina and micromechanical m…
2021
Abstract High performance biocomposites reinforced by sisal fibers, are between the most promising materials that could be used in various fields, from automotive to civil constructions, thanks to their good mechanical performance, as well as to the low cost and the great availability of the fiber. Nevertheless, at present their practical use is prevented by the limited knowledge of their mechanical performance. The results of the present study have shown that the intimate fibrillar structure of the sisal fiber is associated with a high anisotropy involving not only the elastic parameters, but also the damage processes with typical fiber splitting phenomena, that influence noticeably the bi…
A grain-scale model for high-cycle fatigue degradation in polycrystalline materials
2018
Abstract A grain-scale three-dimensional model for the analysis of fatigue intergranular degradation in polycrystalline materials is presented. The material microstructure is explicitly represented through Voronoi tessellations, of either convex or non-convex domains, and the mechanics of individual grains is modelled using a boundary integral formulation. The intergranular interfaces degrade under the action of cyclic loads and their behaviour is represented employing a cohesive zone model embodying a local irreversible damage parameter that evolves according to high-cycle continuum damage laws. The model is based on the use of a damage decomposition into static and cyclic contributions, a…
Modelling intergranular and transgranular micro-cracking in polycrystalline materials
2018
Abstract In this work, a grain boundary formulation for intergranular and transgranular micro-cracking in three-dimensional polycrystalline aggregates is presented. The formulation is based on the displacement and stress boundary integral equations of solid mechanics and it has the advantage of expressing the polycrystalline problem in terms of grain boundary variables only. The individual grains within the polycrystalline morphology are modelled as generally anisotropic linear elastic domains with random spatial orientation. Transgranular micro-cracking is assumed to occur along specific cleavage planes, whose orientation in space within the grains depend upon the crystallographic lattice.…
A microstructural model for homogenisation and cracking of piezoelectric polycrystals
2019
Abstract An original three-dimensional generalised micro-electro-mechanical model for computational homogenisation and analysis of degradation and micro-cracking of piezoelectric polycrystalline materials is proposed in this study. The model is developed starting from a generalised electro-mechanical boundary integral representation of the micro-structural problem for the individual bulk grains and a generalised cohesive formulation is employed for studying intergranular micro-damage initiation and evolution into intergranular micro-cracks. To capture the electro-mechanical coupling at the evolving damaging intergranular interfaces, standard mechanical cohesive laws are enriched with suitab…
Grain-boundary modelling of hydrogen assisted intergranular stress corrosion cracking
2018
Abstract A novel hybrid strategy for modelling intergranular hydrogen embrittlement in polycrystalline microstructures is proposed. The technique is based on a grain-boundary integral representation of the polycrystalline micro-mechanics, numerically solved by the boundary element method, coupled with an explicit finite element model of the intergranular hydrogen diffusion. The intergranular interaction between contiguous grains in the aggregate is modelled through extrinsic cohesive-frictional traction-separation laws, whose parameters depend on the concentration of intergranular hydrogen, which diffuses over the interface according to the Fick’s second law, inducing the weakening of the i…