Simulation of Crack Path in SiC Particle-Dispersed Al2O3 Composites.

Abstract

The propagation behavior of a two dimensional continuous crack is simulated in a SiC particle dispersed Al2O3 matrix composite along with the related variation of fracture resistance with crack extension, Stress intensity factors at the tip of a multiply deflected crack during propagation are calculated numerically by the body force method, in which stresses around the crack tip are represented by superposing externally applied stresses on residual ones. The fracture resistance decreases with crack extension when the crack approaches a particle, but increases up to 2.5 times the matrix toughness when it leaves the particle. The residual compressive stress in the radial direction, resulting from the thermal expansion mismatch between SiC particle and Al2O3 matrix, enhances the apparent fracture resistance of interface. The crack propagation behavior is simulated for both cases of weak and strong interface under the assumption of no failure in dispersed particles. It is found that the influence of interfacial toughness is minimal for the entire fracture resistance. By averaging the simulated fracture resistance curves, a rising R-curve behavior is observed.