Abstract

A novel algorithm to reproduce the arrangement of grains in polycrystalline materials was recently published by the authors. In this original approach, a dense package of circles (or spheres) with the same distribution as the grains is generated to produce a set of Voronoi cells that are later modified to Laguerre cells representing the original structure. This algorithm was successfully applied to materials with somewhat equidimensional grains; however, it fails for long‐shaped grains. In this paper, modifications are provided in order to overcome these drawbacks. This is accomplished by moving each vertex of the Voronoi cells in such a way that the vertex should be equidistant from the particles with respect to the Euclidean distance. The algorithm is applied to packages of ellipses and spherocylinders in 2D. An example for a package of spheres is also provided to illustrate the application for a simple 3D case. The adherence between the generated packages and the corresponding tessellations is verified by means of the Jaccard coefficient (J). Several packages are generated randomly and the distribution of J coefficients is investigated. The obtained values satisfy the theoretical restraints and the quality of the proposed algorithm is statistically validated.

Abstract

The non-linear behaviour ocurring in symmetrical angle-ply laminates formed by unidirectional layers of carbon fiber reinforced polymeric matrix (CFRP), known as pseudo-ductility, has been previously studied numerically and experimentally under different uniaxial, biaxial and bending loads. This phenomenon is associated with different mechanisms which affect the mechanical behaviour of the material: large permanent strains, fiber reorientation and matrix cracking. The present study is based on a microscale approach through simulations based on the Finite Element Method (FEM), with the aim of predicting the homogenized response of these laminates subjected to multiaxial in-plane. The micromechanical model is based on a Representative Volume Element (RVE) where Periodic Boundary Conditions (PBC) are applied, together with a non-linear material model of the matrix and a cohesive interface between fibre and matrix. In addition, the implementation of the model is updated to be able to reproduce any plane stress state in a [±45]_S laminate, without the need to add other meso- or macroscale models.

Abstract

This work investigates the behavior of unidirectional composite materials through a microscale modeling approach, with a particular focus on crack initiation and propagation under transverse and shear loading. Representative Volume Elements (RVEs) are used to model unidirectional plies with varying geometrical configurations, altering both the relative angles between fibers and the distances between them. Simulations are carried out in ABAQUS/Standard, applying periodic boundary conditions (PBCs) to accurately represent the microstructure and integrating cohesive surfaces at the fiber–matrix interfaces to model interactions and failure at these junctions. Additionally, the Extended Finite Element Method (XFEM) is employed to analyze in detail the initiation and propagation of cracks associated with matrix fracture.

This study advances the understanding of the relationship between microstructure and failure mechanisms, offering tools for the design and optimization of composite materials with improved fracture resistance under multiaxial loading conditions. The results show that the relative angle between fiber centers plays a critical role in determining failure mechanisms at the ply level.

Abstract