Boundary element method simulation of the size effect in particle dispersed composites

The size effect of a series of geometrically similar three-point-bend specimens is simulated by a nonlinear multi-zone boundary element method. The manner in which particles are randomly dispersed in a relatively hard matrix can be applicable to various aggregate materials as well as unidirectionally reinforced fiber composites in the transverse plane. A single edge macrocrack and interfacial microcracks randomly distributed between particles and matrix are prescribed as initial defects. The load–deflection curve, the shape, size and location of the fracture process zone are observed with confidence. The nominal strength of the material is in agreement with the Bazant size effect law. Furthermore, the results show that microcracking is essential for the size effect in aggregate quasi-brittle materials.