Adiabatic Shear bands in plane strain deformations of a WHA

We study plane strain thermomechanical deformations of a prismatic body with a rectangular cross-section and made of a tungsten heavy alloy (WHA). Tungsten and iron-nickel-tungsten (Fe-Ni-W) particles are modeled as thermally softening but strain and strain rate hardening. The deformations are assumed to be locally adiabatic and the effect of inertia forces is considered. The body is loaded by applying a normal component of velocity to the opposite edges; the speed increases from zero to the final value in 5 microseconds and is then kept steady there so that the maximum average strain rate is 5000 s(-1). Different volume percentages of Fe-Ni-W par tides are taken to be randomly distributed in the cross-section. It is found that the time history of the compressive load required to deform the body is initially unaffected by the volume percentage of Fe-Ni-W particles. At an average strain of 0.10 these load histories begin to differ somewhat; at any given value of the nominal strain, the decrease in the magnitude of the load is not a monotonic function of the increase in the volume percentage of Fe-Ni-W particles. For a fixed volume percentage of Fe-Ni-W particles, different random distributions result in essentially the same load history but give different patterns of shear bands. For eight randomly distributed Fe-Ni-W particles clustered around the horizontal centroid axis, none of the shear bands passed through any one of these particles. (C) 1998 Elsevier Science Ltd. All rights reserved.