13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Modeling of Damage Evolution in Particulate Reinforced Composites with VCFEM Ran Guo1,*, Wenyan Zhang1, Benning Qu1, Yongjin Chen1 1 Department of Engineering Mechanics, Faculty of Civil Engineering and Architecture, Kunming University of Science and Technology, Kunming 650500, China 2 Faculty of EEFF, Institute of GGHH, City Post Code, Country * Corresponding author: prof.guo@189.cn Abstract The modeling of fatigue crack initiation and propagation for particulate reinforced composites and the study of the behavior of a functionally graded material with interface cracks are facilitated with a new Voronoi Cell Finite Element Method (VCFEM), considering the matrix-inclusion interfacial fatigue crack and matrix fatigue crack. In the new element, all possible contacts on the crack edge are considered by contact seeking and remeshing methods, when the crack is closing under all possible changing loads. The fatigue crack initiates when the fatigue damage exceeds certain critical damage value, and fatigue crack propagation are simulated by gradual seeking crack propagating directions and new crack tips, using a remeshing method that a damaged node at the crack tip is replaced by a pair of nodes, a new crack tip node is assigned at the crack propagating directions and a more pair of nodes are needed to be added on the crack edge near the crack tip in order to better facilitate the free-traction boundary condition. The first example has been given for Particle-reinforced metal-matrix composites with 20 elliptical inclusions to simulate the fatigue crack initiation and propagation under plane stress conditions. It appears that this method is a more efficient way to deal with the interfacial damage of composite materials. In the second example, the results show that the mechanical properties of functionally gradient materials are influenced by the particles’ size, topological structure, and interfacial deboning strength. With the interface cracking the overall stiffness of functionally gradient materials is gradually reduced. Keywords VCFEM, Finite element method, Fatigue crack, Particulate reinforced composites 1. Introduction Particulate-reinforced metal-matrix composites (MMCs) have attracted significant attention in recent times in both the academic community and in the industrial sector. Since MMC combine well-known superior properties such as low density, high strength, stiffness, creep and wear resistance, they are appropriate candidates for numerous aerospace and automotive applications. However, the differences in thermo-mechanical properties of matrix and inclusion develop stresses during fabrication and in service. This may lead to voids nucleation, cracking and decohesion at the interface, which affects seriously fracture properties. The validity of modeling real composites practically with heterogeneities of arbitrary shapes, sizes or dispersions, depends considerably on the consideration of the irregular microstructure. The accurate micromechanical modeling of actual two-phase materials is very complicated due to the irregular microstructural configurations that exist in real materials. A large number of models have been developed to predict the effective elastic properties of heterogeneous materials and their dependence on materials microstructure, such as homogenization theory, cell methods, traditional displacement based FEM, A hybrid finite element approach by Zhang and Katsube[1], a Voronoi Cell Finite Element Method (VCFEM) for modeling of non-uniform microstructures with heterogeneities introduced by Ghosh and co-workers in a series of papers[2~3] and a series of works on VCFEM are done[5-6]. Introduction a new Voronoi cell finite element model (VCFEM) on the base of the assumed stress hybrid variational principle to model fatigue crack initiation and propagation in a Particle-reinforced metal-matrix composites (MMCs) with heterogeneities of arbitrary shapes, sizes or dispersions is the objective of the present study. In the new element, considering the
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