Simulation of crack propagation process in particle-dispersed composites

Crack path is simulated in particle-dispersed composites along with the related variation of fracture resistance with crack extension. The direction of crack propagation is influenced by the geometrical crack shape and residual stresses due to thermal expansion mismatch between particle and matrix. The direction is determined by the criterion of maximum energy release rate at crack tip. The simulation is conducted on the SiC matrix composites dispersed with Al2O3 particles, where the composites are assumed to be elastically isotropic. Due to the higher thermal expansion of Al2O3 particles, residual tensile stresses in the radial direction of the particles are generated within the matrix, and cracks propagating near the particles have a tendency to be repelled. The fracture resistance increases with crack extension when the crack approaches the particle, and decreases when propagates in the tensile stress fields around the particle. The entire fracture resistance in the composites of 10 vol. % particles shows a lower value than that of matrices, due to the interaction with the residual tensile stresses in the radial direction of the particles.