NONEQUILIBRIUM STATISTICAL-THEORY OF DAMAGE FRACTURE FOR QUASI-BRITTLE MATERIALS

A nonequilibrium statistical theory of damage fracture is developed on the foundation of nonequilibrium statistical theory of fracture. The evolution of microcracks is regarded as the elementary process of dama ge to the material structure. The failure probability of the material due to the evolution of microcracks under the action of applied load m ay be defined as the damage variable. By combining the evolution equat ion, the weakest link theory and Griffith's failure criterion, a new p artial differential equation which universally describes the evolution of damage-failure probability is found. This equation not only charac terizes the kinetic process of damage-failure evolution, but also real izes the relationships between the mechanism of damage-the initiation, growth of microcracks, and the statistical consequences of damage-the degradation of material properties. Then the theory is applied to stu dy the damage and fracture of 96% AL(2)O(3) ceramics. The damage-failu re probability and the lifetime of materials are calculated and the ef fect of inhomogeneity of microstructure on material properties is also discussed. Copyright (C) 1996 Elsevier Science Ltd