Adiabatic deformation and strain localization

The strain localization phenomenon of adiabatic shear is generally attributed to a plastic instability arising from a thermal softening effect during adiabatic or near-adiabatic plastic deformation. Strain localization was studied under conditions of both quasistatic and dynamic deformation. Application to the simulation of ballistic penetration is in progress. Experimental evidence indicates the existence of a pressure-dependent strain softening effect attributed to subcritical shear microcracks which contributes to shear instability in mild steels. This phenomenon may also operate in high-strength steels, giving rise to a pressure-dependent beta parameter. Experiments are designed to determine the relative importance of this effect in the adiabatic deformation of high-strength steels and its possible role in ballistic penetration.