The response of silicon carbide and boron carbide subjected to shock-release-reshock plate-impact experiments

Abstract
This article presents experimental and computational results of silicon carbide (SiC) and boron carbide (B₄C) subjected to shock-release-reshock plate-impact conditions. The significance of these tests is that they provide a measurement of the strength of ceramic after it has been permanently deformed (damaged) and then unloaded. The experiments use an impactor configured to produce an initial shock, followed by a release, followed by a second shock. The first shock loads the ceramic above the Hugoniot Elastic Limit (HEL-1) producing plastic deformation and damage. The release wave unloads the ceramic producing additional plastic deformation and damage. The second shock reloads the damaged ceramic to another Hugoniot stress state. The wave profile produced from the second shock produces another HEL (HEL-2), a direct measure of the strength of the damaged ceramic. Computations are used to analyze the experiments and determine the plastic strain produced during unloading and the strength of the ceramic in the second shock. Three tests are presented for SiC and three for B₄C. The results indicate that SiC maintains its strength when strained to over 8% plastic strain, while B₄C appears to lose strength after exceeding the HEL-1. It also appears that the process of unloading damaged ceramic does not affect the strength and/or the moduli for these two materials.