The Analysis of Elastic-Plastic Deformation and Stress at Finite Strain and Their Evaluation.

Abstract

Abstract : The facility of structural metals to be deformable to large strains without fracturing is often needed in the manufacturing of structural components (metal forming) and in the operation of a structure (e.g. armor penetration, crashworthiness and earthquake resistance). Rational design of a structure therefore often demands stress and deformation analysis in the presence of finite strain. Investigations of several aspects of elastic-plastic theory at finite deformation have been carried out on this project including the nonlinear coupling of elastic and plastic strains when the deformation is large, the representation and analysis of plastic strain-induced anisotropy and the evaluation of stress distributions in forming processes by the finite-element method. Of particular interest and importance, because what was until recently thought to be the correct formulation of the theory turned out to introduce huge errors in stress analysis, is the prediction of stress and deformation distributions in material exhibiting plastic strain-induced anisotropy of the type associated with the Bauschinger effect. State-of-the-art calculations presented at a workshop, co-sponsored by ARO, predicted oscillating shear stress generated by monotonically increasing shear strain to large strains.