Improved Constitutive Equations for Modeling Strain Softening—Part I: Conceptual Development

Abstract

A microstructurally based model of nonelastic deformation is proposed which is capable of predicting strain softening as well as a wide range of other deformation behaviors. The model, an extension of the MATMOD constitutive equations, now includes representations of both short range and long range internal stresses, strengthening due to homogeneous and heterogeneous microstructures, and dynamic recovery. Additional conceptual improvements regarding the interactions between various sources of work hardening and the influence of straining direction upon deformation induced microstructures are also introduced. The physical origins of these extensions, their relationship to strain softening, and their implementation in the new model, MATMOD-4V, are presented.