Simulations of semi-infinite penetration

Idealised materials deformation models have been used in conjunction with an analytical approach to study the penetration of kinetic energy penetrators into semi-infinite targets. Numerical simulations were carried out using the DERA cAst Euler hydrocode. Deformation models used a modified form of the Armstrong-Zerilli bcc form [1, 2]. The projectile model included the physical and equation of state properties for a dense alloy with deformation defined by incorporating idealised constants in the model. It was shown that there is little variation in penetration depth within the range of properties likely to be achievable in practice. High strain rate sensitivity produces very high transient strength which provides essentially rigid body penetration. Equivalent performance was difficult to achieve by increasing the static strength alone because of the thermal softening contribution. In contrast thermal softening, of the right type, allows the curvature and constraint in the penetrator nose to produce a small head in a different way. In this case the strength of deformed material is decreased significantly allowing the head to curve around sharply, creating only a small diameter cavity in the target.