An investigation into spallation of titanium alloy using plate impact experiments and simulation

Abstract
Spallation studies have proved invaluable in determining the spall strengths of these materials, which are then used for various assessment and design purposes. However, there are still many uncertainties regarding the spallation process, particlllarly in alloys, due to the difficulty in developing predictive constitutive and failure models for these materials. One difficulty is that the simulation results depend as much on the constitutive and fracture behaviour as the numerical treatment, particularly post failure. The purpose of this paper is to isolate these effects by using very well controlled data for Ti6Al4Vn alloy under a range of impact scenarios using VISAR. These experiments have been simulated using the Lagrangian hydrocode DYNA and the Eulerian hydrocode CTH. The study renforces the view that the simulation of uniaxial spall signais, represents a significant challenge for the constitutive and fracture models, as well as the post failure numerical treatment within the hydrocode. The results of the simulations are discussed in the wider context of validation of constitutive and fracture models and the lack of real understanding concerning the spallation processes in these alloys.