LARGE-STRAIN CONSTITUTIVE MODELING AND COMPUTATION FOR ISOTROPIC, CREEP ELASTOPLASTIC DAMAGE SOLIDS

A three-dimensional fully coupled creep elastoplastic damage model at finite strain for isotropic non-linear material is developed. The model is based on the thermodynamics of an irreversible process and the internal state variable theory. A hyperelastic form of stress-strain constitutive relation in conjunction with the multiplicative decomposition of the deformation gradient into elastic and inelastic parts is employed. The pressure-dependent plasticity with strain hardening and the damage model with two damage internal variables are particularly considered. The rounding of stress-strain curves appearing in cycling loading is reproduced by introduction of the creep mechanism into the model. A numerical integration procedure fdr the coupled constitutive equations with three hierarchical phases is proposed. A consistent tangent matrix with consideration of the fully coupled effects at finite strain is derived. Numerical examples are tested to demonstrate the capability and performance of the present model at large strain.