Response of aluminum nitride (including a phase change) to large strains, high strain rates, and high pressures

This article contains a description of a computational constitutive model for brittle materials subjected to large strains, high strain rates, and high pressures. The focus of this model is to determine the response of aluminum nitride under high velocity impact conditions that produce large strains, high strain rates, and high pressures. The strength is expressed as a function of the pressure, strain rate, and accumulated damage; and it allows for strength of both intact and failed material. The pressure is primarily expressed as a function of the volumetric strain, but it also includes the effect of bulking for the failed material. For materials without a phase change this model is an extension of the previous Johnson-Holmquist models for brittle materials. The primary new feature of this model is the capability to include a phase change, and this is required for aluminum nitride. Computations are performed to illustrate the capabilities of the model, to compare computed results to experimental results, and to provide an understanding of the behavior of aluminum nitride under the conditions of high velocity impact. (C) 2003 American Institute of Physics.