Resonant reflection of two-dimensional acoustic waves from shocks in solids

The problem of spontaneous emission of sound waves from shocks in solids is investigated. A self-consistent model of the medium is constructed that allows the calculations of the various thermodynamic properties such as the internal energy, the entropy, the Gruneisen parameter and in particular the Mach number behind the shock. The latter is employed in calculating the stability criterion that determines whether spontaneous acoustic emission occurs behind the shock. The experimental shock adiabatic curves are reproduced by the model. A simple explicit form of the stability criterion is derived in terms of Gruneisen parameter of the unperturbed medium and the maximum compression ratio. It is shown that spontaneous emission may occur in metals under available experimental conditions.