Numerical Simulation of Adiabatic Shear Bands in Ti-6Al-4V Alloy Due to Fragment Impact

Abstract : Current distributions of continuum mechanics codes used by the Army do not have the capability to model failure associated with plastic shear localizations in ballistic applications, such as plugging failure of targets due to ballistic impact by blunt-nosed projectiles. This paper discusses the development and validation of a computational capability to accurately model highly localized deformations in complex projectile-target interactions germane to survivability and lethality technologies for the Army's Future Combat Systems. Onset and propagation of adiabatic shear bands are investigated both experimentally and computationally by studying the ballistic impact of 20-mm steel fragments against Ti-6Al-4V plates. Numerical simulations are carried out using a three-dimensional localization model being developed for CTH, an Eulerian wave propagation code. A failure criterion that uses homogenous material response and scaling laws to estimate the plastic strain at which stress collapse due to adiabatic shear should occur, for rate dependent, work-hardening, thermally softening materials, has been implemented into CTH, and is used as a nucleation criterion. Numerical results provided good agreement with experimental observations. 1.