Abstract

Impulsive Fracture of Solids Induced by Propagation-Enhanced Nonlinear Elastic Surface Waves

A.M.Lomonosov (General Physics Institute, Moscow, Russia); P.Hess (Institute of Chemical Physics, University of Heidelberg, Heidelberg, Germany)

e-mail: lom@kapella.gpi.ru

In contrast to nonlinear sound waves in fluids nonlinear surface acoustic waves (SAWs) can generate steep shock fronts with stress magnitudes that grow with propagation distance. In media with sufficiently low losses this leads to the effect of SAW-induced fracture. We present first experimental observations on failure of materials with different types of elastic nonlinearity, such as isotropic fused silica and crystalline silicon. SAW pulses with high amplitudes were launched by means of a pulsed laser source and detected by a probe-beam-deflection technique. The stress tensor was calculated to evaluate the fracture strength of the materials with respect to the impulsive load generated by the SAW pulses. A significant asymmetry of the material strength with respect to the reversion of the SAW propagation direction has been observed in silicon. This effect is explained theoretically and described quantitatively.

Section : 2