Computer simulated experiments on fracture toughness of particle-dispersed composites

The fracture behavior of a series of geometrically similar three point bend specimens is simulated by a nonlinear multi zone boundary element computer program. The material is based on Al 2O 3 SiC (p) ceramic in which particles are randomly dispersed in a relatively soft matrix. A single edge main crack and a large number of interfacial microcracks randomly distributed between particles and matrix are prescribed. The load deflection curve and the spread of the fracture process zone (FPZ) are observed with confidence. The computer simulated results show that the fracture toughness of the material increases with increasing specimen dimension and becomes constant when the specimen size exceeds a critical value. A practical specimen size for predicting the true fracture toughness of aggregate materials is proposed.