Strength and Inelastic Deformation in Shocked Polycrystalline Silicon Carbide

摘要

The objective of this research project was to quantify the response of shocked ceramics, including strength in the shocked state, to understand the mechanisms governing inelastic deformation at high stresses and high strain- rates in these materials. In-situ, piezoresistance stress gauge measurements were obtained in dense, polycrystalline silicon carbide (SiC) samples subjected to plane wave loading. A significant effort was carried out to ensure a self-consistent analysis of the lateral piezoresistance gauge data. Analysis of the longitudinal data revealed an inelastic response that could be modeled using either a strain hardening, plasticity model or a pressure-dependent strength model with stress relaxation. Experimental measurements and analysis of the lateral gauge data in SiC, currently underway, are needed to develop a comprehensive understanding of shocked SiC. Preliminary experiments and numerical calculations were completed to undertake combined compression and shear wave measurements in the SiC. The use of lateral piezoresistance gauges, and compression-shear measurements provide independent corroborations of material strength in the shocked state. This determination is important for understanding the differences in the compressive and tensile response of shocked ceramics.