Author(s)

H. Couque

Abstract

The influence of pressure on dynamic failure under compression of a highstrength tungsten alloy and a hardening steel was investigated. Two dynamic compression tests were employed. The first one, a symmetric Taylor test, provides low pressure data while the second one, a modified version of the hat test called the hydrodynamic hat test, generates data at pressures up to 1.5 GPa. Failure strain data were obtained from numerical simulations of the tests. For both metals, the increase of pressure was found to lower the failure strain associated with adiabatic shear banding preceding shear failure. These results are interpreted through a reduction of the plastic work being converted in heat with the increase of pressure delaying adiabatic shear band formation. 1 Introduction The knowledge of the dynamic failure mechanisms for metals subjected to combined compression and pressure is of interest for the interpretation of ammunition penetration process and ship formation during machining. Bai and Dodd suggested that the compression failure strain increases up to a critical pressure of 0.4 GPa [1] based on the interpretation on the failure mechanisms following adiabatic shear band (ASB) formation in steel and copper. This increase is interpreted through high pressures delaying void nucleation and growth within the shear band. This analysis goes along with post-mortem observations of armor steels revealing ASB without failure. With regard to the influence of pressure on ASB formation, it is only recently that the influence of pressure has been investigated with the introduction of a hydrodynamic hat specimen designed to generate data at a pressure of 1.5 GPa [2].

Keywords