Micromechanics of damage in random composites

We study mechanical breakdown, due to spatially evolving microcracking, in two-dimensional composite materials with randomly distributed inclusions or holes. While both the matrix and the inclusion phases are described by two elastic-brittle stress-strain laws, the immediate questions are: 'what are the effective response laws of the composite, and the damage patterns, as a function of the stiffness ratios and strength ratios of both phases as well as of their volume fractions?' Our answers are based on experiments and computer simulations of spring networks and/or finite elements.