Yield Criteria for Pressure-sensitive Materials based on Meso-mechanical Analysis

Investigation on mechanical properties of rock, soil and powder metallurgy is an important subject in study of damage constitutive models. These materials contain micro-voids (such as defects, inclusions and cracks) and perform pressure sensitivity. Unlike metal materials, hydrostatic pressure can influence plastic yield of these materials. Following the modified Gurson model in meso-mechanics and considering the meso-compressibility, this paper focuses on plastic limit analysis of micro-deformation mechanism of these materials. The two-independent-parameters criterion is taken as matrix yield function and spherical voids as the represent unit cell. The macroscopic stress and strain rate related to micro structure parameters are derived via upper-bound theorem. Then the macroscopic yield function (containing micro structure parameters) is established. Finally, the properties of macroscopic yield surfaces are studied by setting different values of these micro parameters. This paper provides theory foundations for materials damage and design.