Critical strain ranking of 12 materials in deformations involving adiabatic shear bands

摘要

Batra and Kim (1992) studied the initiation and growth of shear bands in 12 materials deformed in simple shear. Each material was modeled by the Johnson-Cook (1983) law, values of material parameters were taken from Johnson and Cook's (1983)paper, and the effects of inertia forces and thermal conductivity were included. However, materials generally are rarely tested in simple shear and the material data used was derived from tests conducted over a moderate range of strains, strain rates, and temperatures. In this Note, we report results of numerical simulation of torsion tests similar to those performed by Marchand and Duffy(1988) on HY-100 steel and rank 12 materials according to the values of the nominal strain at which the torque begins to drop precipitously. Values of material parameters taken from Rajendran's report (1992) and likely to be valid over a large range of strains, strain rates, and temperatures are used. However, the effect of thermal conductivity has been neglected becausethe computer code DYNA3D (Whirley and Hallquist, 1991) employed to study the problem assumes locally adiabatic deformations. Batra and Kim (1991) have shown that for simple shearing deformations of viscoplastic materials, realistic values of thermalconductivity have little effect on the values of the nominal strain at which deformations begin to localize and thus shear bands initiate.