Analysis of a strain softening constitutive model

The paper first examines the question of uniqueness of a basic yet simplified constitutive model with strain softening. It is shown that the constitutive equations lead to a unique solution for the case of rate-dependent as well as rate-independent formulation and its implementation in finite element analysis shows mesh size insensitivity in the hardening and softening regimes. Conditions for formation of narrow shear bands are developed and discussed. It is shown that as the damage accumulates the material approaches localization of deformation.