MACROSCOPIC FRACTURE CHARACTERISTICS OF RANDOM PARTICLE-SYSTEMS

This paper deals with determination of macroscopic fracture characteri stics of random particle systems, which represents a fundamental but l ittle explored problem of micromechanics of quasibrittle materials. Th e particle locations are randomly generated and the mechanical propert ies are characterized by a triangular softening force-displacement dia gram for the interparticle links. An efficient algorithm, which is use d to repetitively solve large systems, is developed. This algorithm is based on the replacement of stiffness changes by inelastic forces app lied as external loads. It makes it possible to calculate the exact di splacement increments in each step without iterations and using only t he elastic stiffness matrix. The size effect method is used to determi ne the dependence of the mean macroscopic fracture energy and the mean effective process zone size of two-dimensional particle systems on th e basic microscopic characteristics such as the microscopic fracture e nergy, the dominant inhomogeneity spacing (particle size) and the coef ficients of variation of the microstrength and the microductility. Som e general trends are revealed and discussed.