Failure Fronts in Brittle Materials and Their Morphological Instabilities

Report No. ARL-TR-3660
Authors: Michael A. Grinfeld, Scott E. Schoenfeld, Tim W. Wright
Date/Pages: September 2005; 16 pages
Abstract: This report outlines the results of the effort to suggest a theoretical method of describing failure fronts in glasses and ceramics. There are various observations and experiments showing that in addition to standard shock-wave fronts, which propagate with transonic velocities, other much slower wave fronts can propagate within glass or ceramic substances undergoing intensive damage. These moving fronts propagate into intact substance, leaving intensively damaged substance behind them. They have been called failure waves. In this report, we model them as sharp interfaces separating two states?the intact and comminuted states. The approach is based on an analogy between failure fronts and fronts of slow combustion. Two main results are announced. One of them concerns the speed of a failure wave driven by oblique impact of a brittle target, and the other establishes a criterion for morphological instability of failure fronts.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2005