CAVITY GROWTH IN CERAMIC MATERIALS UNDER MULTIAXIAL STRESS STATES

The paper considers the growth of grain-boundary cavities and cracks under multiaxial stress states in fine crystalline materials where the cavity and crack spacing is of the order of the grain-size. This situation is typical of that observed when testing engineering ceramics. The results are presented in the form of a series of constant void growth-rate surfaces. It is demonstrated that the shape of these surfaces can change considerably as the distribution of voids and cracks and mechanism of damage growth change. It is evident from this study that more detailed analyses of void and crack growth are required employing more realistic distributions of damage. At the same time there is a need for extensive testing of ceramic materials under multiaxial stress states to aid the development of, and to fully test, these models.