Analysis of failure modes in impulsively loaded pre-notched steel plates

Abstract

We analyze transient plane strain thermomechanical deformations of a pre-notched 4340 steel plate impacted by a 4340 steel projectile in the direction of two parallel notches, and study the influence of the impact speed and notch tip radius on the localization of the deformation. The plate configuration is identical to that in Kalthoff's experiments (1987, 1988). There is no failure or fracture criterion included in our work. However, the computed evolution of stress and plastic strain fields strongly suggest that with an increase of impact speed and decrease in notch tip radius, there is a failure mode transition from a tensile crack opening at approximately 70° to the notch ligament to an adiabatic shear band propagating at −5° to −15° to the notch ligament. This is in qualitative agreement with Kalthoff's findings.