Constitutive Equations of Yield Stress Sensitivity to Strain Rate of Metals: A Comparative Study

Abstract EN

Several constitutive equations have proposed to model the strain rate sensitivity of metals to strain rate.

This paper presents a comparative of six equations reported in the open literature.

All equations are used to fit the yield stress of three copper materials and one steel material at two different temperatures.

A specific cost function and an optimization problem are defined.

The authors recommend the use of the Cowper-Symonds equation or a modified-Eyring equation as both of them fit well the experimental data while using only three material constants.

A modified flow stress Johnson-Cook equation is then proposed for metallic materials.