Consistent tangent matrices for density-dependent finite plasticity models

The consistent tangent matrix for density-dependent plastic models within t he theory of isotropic multiplicative hyperelastoplasticity is presented he re. Plastic equations expressed as general functions of the Kirchhoff stres ses and density are considered. They include the Cauchy-based plastic model s as a particular case. The standard exponential return-mapping algorithm i s applied, with the density playing the role of a fixed parameter during th e nonlinear plastic corrector problem. The consistent tangent matrix has th e same structure as in the usual density-independent plastic models. A simp le additional term takes into account the influence of the density on the p lastic corrector problem. Quadratic convergence results are shown for sever al representative examples involving geomaterial and powder constitutive mo dels. Copyright (C) 2001 John Wiley & Sons, Ltd.