On the shock induced failure of brittle solids

The response of brittle materials to uniaxial compressive shock loading has been the subject of much recent discussion. The physical interpretation of the yield point of brittle materials, the Hugoniot elastic limit (HEL), th e dependence of this threshold on propagation distance and the effect of po lycrystalline microstructure remain to be comprehensively explained. Eviden ce of failure occurring in glasses behind a travelling boundary that follow s a shock front has been accumulated and verified in several laboratories. Such a boundary has been called a failure wave. The variations of propertie s across this front include complete loss of tensile strength, partial loss of shear strength, reduction in acoustic impedance, lowered sound Speed an d opacity to light. Recently we have reported a similar behaviour in the po lycrystalline ceramics silicon carbide and alumina. It is the object of thi s work to present our observations of these phenomena and their relation to failure and the HEL in brittle materials. (C) 1998 Elsevier Science Ltd. A ll rights reserved.