STUDY ON ACCURACY OF FINITE-ELEMENT SOLUTIONS IN ELASTOPLASTIC LARGE-DEFORMATION (EFFECTS OF SHAPE FUNCTION AND NUMERICAL-INTEGRATION, AND APPLICATION OF MIXED METHOD)

We discuss the accuracy of finite-element solutions for metals possess ing dominant plasticity, resulting in an incompressible response in a large deformation field. It is known that poor numerical solutions are obtained for the constrained problem due to incompressibility of defo rmed metals, but they can be improved by selecting an appropriate shap e function and numerical integration technique, as well as by applying the mixed method derived from Lagrangian multipliers. Many studies ha ve been made for rigid-plastic finite-element solutions so far, but la rge-deformation elastoplastic structural analysis is rarely discussed in the literature. In this work, we discuss the advantages of such tec hniques in large-deformation analysis using the Jaumann stress rate an d isotropic hardening hypoelasticity model.