Mixed Finite Elements with Enhanced Plastic Behavior

摘要

Two kinds of mixed elements for the analysis of elastoplastic problems are presented. The elements are 2D quadrangular finite elements whose variational framework is based on the weak statement of the equilibrium, compatibility and of the plastic loading-unloading conditions. In this context the interpolation of three fields is required: displacements, stresses and plastic multiplier. The former field is based on a standard interpolating pattern continuous among the elements. The other fields are represented locally inside the elements, giving more freedom in the choice of the internal interpolating patterns and, eventually, more richness. In particular enhanced patterns for the plastic multiplier are experimented in order to obtain high performance behavior also in the plastic field. The numerical experimentation highlights reliability and good performance of the proposed elements.