A Constitutive Model for Damaged and Powder Silicon Carbide

Abstract

To perform numerical simulations of ballistic impact into ceramic targets, suitable constitutive models are needed for intact, damaged and powder ceramic. For ballistic applications some constitutive models are already available in the literature but they are rarely based entirely on mechanical characterization. In fact, the parameters published are usually a blend of the material properties available and some tuning to ballistic experiments. This paper explains how a constitutive equation can be obtained from the compression testing of ceramics under confinement. Since the test procedure and results are described in another paper in this conference, this paper will focus on the analytical and numerical models performed to support the testing. The tests provide stress vs. strain and stress vs. hoop strain curves that, with a simplified mathematical model developed and described in this paper, can be plotted as stress vs. pressure curves. Numerical models of the confined tests were also performed to both support and supplement the analytical model. First they were used to check that the analytical model was correctly implemented and then, due to the inherent limitations of the analytical model (only valid during elastic deformation), they help to explore constitutive models like Drucker-Prager with a cap and Johnson-Holmquist. The final outcome of this paper is a constitutive model for damaged and powder SiC-N that can be used for ballistic simulations and has its origin entirely in a mechanical characterization procedure.