Impact shear-numerical analyses of ASB evolution and failure for Ti-6AI-4V alloy

Abstract
In this contribution a study is reported on a shear zone evolution at high strain rates for Ti-6AI-4V alloy. Such process of deformation, leading to development of Adiabatic Shear Band (ASB), is typical for fast and impact shearing. A very special experimental technique developed at LPMM-Metz bas permitted for shear tests at a wide range of strain rates and also for development of an advanced constitutive relation valid for that range of strain rates and also for a range of temperatures (range of strain rates from 10 ^-4 I/s to about 10 ⁵ 1/s). This experimental technique called the Modified Double Shear has been applied to test Ti-6AI-4V alloy. In order to estimate the effect of stress concentration on the sensitivity to ASB triggering four different specimen geometries with different stress concentrators were tested and analyzed. After identification of all material constants for Ti-6AI-4V alloy in the advanced constitutive relation, this relation has been introduced into the finite element code ABAQUS Explicit. The constitutive relation accounts for the effects of strain hardening, rate sensitivity and thermal softening. In this way a complete dynamic approach with elastic-plastic wave propagation, adiabatic shear band development and failure could be studied numerically for all four geometries with different stress concentrators. In addition, the Critical Impact Velocity (CIV) in shear has been estimated analytically and numerically for Ti-6AI-4V. A very good agreement between experiments and numerical simulations are achieved.