SIMULATION OF CRACK-PROPAGATION PROCESS IN PARTICLE-DISPERSED COMPOSITES

Crack path is simulated in particle-dispersed composites along with th e related variation of fracture resistance with crack extension. The d irection of crack propagation is influenced by the geometrical crack s hape and residual stresses due to thermal expansion mismatch between p article and matrix. The direction is determined by the criterion of ma ximum energy release rate at crack tip. Tile simulation is conducted o n 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, an d cracks propagating near tile particles have a tendency to be repelle d. The fracture resistance increases with crack extension when the cra ck approaches the particle, and decreases when propagates in the tensi le stress fields around the particle. The entire fracture resistance i n 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.