The most common mechanical test for characterizing metals is the tension test. A specimen is put in a machine which pulls it at a prescribed rate and simultaneously records the load on the specimen.
The most popular method for integrating the plasticity equations for isotropic von Mises plasticity is radial return, developed by Wilkins for HEMP and Maenchen and Sack for TENSOR, two finite difference codes developed at Lawrence Livermore National Laboratory.
In the evaluation of the tangent sti ness matrix, the material tangent matrix is required. The continuum tangent matrix was developed in a previous article, and it is frequently used in nite element calculations.