The research addresses a key issue in damage mechanics of brittle solids and plans to develop a new approach utilizing micromechanics concepts to understand the fracture and damage characteristics of brittle materials including granular solids and concrete. The research plan includes experimental and theoretical investigations of inelastic response and failure mechanisms of materials which contain specific microdefects. Controlled model experiments will be conducted where the geometry and other characteristics of the defects that produce micro cracking and inelastic flow are prescribed. This procedure will allow the observation of the evolution of the microstructure in the course of deformation. This will provide quantitative estimates of the macroscopic parameters which characterize stresses and strains. Model analyses will be performed utilizing rigoroud mechanics. Theoretical models will be developed and verified by experimental observations. The Principal Investigator is in intetnationally recognized expert in fracture mechanism of brittle and granular solids. The institution has an excellent laboratory facility to conduct this research. An award is recommended.