MATERIAL CONSTITUTIVE LAW FOR LARGE STRAINS AND STRAIN RATES. TECHNICAL NOTE

This note comments on a strain rate pattern found in tensile tests. This strain rate pattern readily suggests that the Cowper-Symonds (CS) equation (Jones, 1989) relating the static and dynamic flow stresses with the strain rate is not valid for a broad range of strains unless its coefficients change. A modification of the CS equation is proposed, and good prediction of the dynamic flow stress at any strain and strain rate level was obtained.