A physically based constitutive model for fcc metals with applications to dynamic hardness

Abstract

A constitutive model is developed in this work to describe the mechanical behavior of face centered cubic (fcc) metals under a wide range of temperatures and strain rates. The model is based on the dependence of the activation energy on temperature, strain rate, and stress. An expression for the flow stress is proposed in terms of micromechanical terms such as mobile dislocation density and Burgers vector as well as macromechanical based state variables such as stress and material constants that include threshold and transition temperature. The proposed model is used to simulate the experimental results of oxygen free high conductivity (OFHC) copper at different temperatures and strain rates in order to obtain the different model parameters. The model shows good capability in capturing the coupling between strain rate and temperature, plastic strain and strain rate, and plastic strain and temperature. The model is used to characterize the hardness at low and high strain rates for a representative strain of 8%.