Finite Strain Micromorphic Pressure-Sensitive Plasticity

A finite strain micromorphic pressure-sensitive plasticity model is formulated starting with thermodynamically conjugate stresses and plastic deformation rates in the reduced dissipation inequality, written in the intermediate configuration. Isotropic linear elasticity and nonassociative Drucker–Prager plasticity with cohesion hardening/softening are assumed for the constitutive equations. The reduced dissipation inequality dictates three levels of plastic evolution: (1) evolution of Fp , the plastic part of the deformation gradient; (2) evolution of χp , the plastic part of the microdeformation tensor; and (3) evolution of ∇¯ χp , the covariant derivative of χp . A semi-implicit time integration of the stress and plastic evolution equations is outlined after assuming small elastic deformations and Cartesian coordinates for the current configuration.