Numerical implementation of constitutive integration for rate-independent elastoplasticity

摘要

In this paper, constitutive integration for rate-independent, small deformation elastoplasticity is studied. Smooth yield surfaces and work/strain hardening are assumed. Both associative or non-associative flow rules are considered. An Euler backward algorithm is applied for constitutive integration. Tangent moduli that are consistent with the Euler backward algorithm, i.e. a so-called consistent tangent operator, are derived. Emphasis is placed on numerical implementation of the Euler backward algorithm into finite element codes using such a consistent tangent operator. In particular, a commercial code ANSYS is considered. Numerical examples, including materials sensitive and insensitive to hydrostatic stress, are used for the verification of the implementation. A comparison of the algorithmic performance to an explicit Euler forward algorithm is given and the superiority of the Euler backward algorithm is demonstrated.