Failure Modes of Ductile Metal Plates under Normal Impact by Flat-Ended Projectiles

This paper examines the failure modes of ductile metal plates subjected to impact by rigid flat-ended projectiles at normal incidence. General speaking, there are two failure modes which can occur in a ductile metal plate: simple shear failure with global deformation, and localized adiabatic shear plugging. Based on the thermoplastic constitutive relationship of Bai and Johnson, an adiabatic shear plugging model is first proposed. When combined with the Wen-Jones model which describes simple shear failure with global response, a critical condition for the change in these two failure modes is obtained. It transpires that the present theoretical predictions are in good agreement with available experimental observations in terms of failure modes and ballistic limits.