Nonlinear longitudinal strain‐wave propagating in an elastic plate with nonequilibrium laser‐generated defects

Abstract

AbstractThe propagation of long nonlinear longitudinal strain waves in an isotropic elastic plate is studied in the context of a model that takes into account the joint dynamics of elastic displacements in the medium and the concentration of the nonequilibrium laser‐generated point defects (vacancies and interstitials). The input equations of the problem are reformulated in terms of only the total displacements of the medium points. In this case, the presence of lattice defects manifests itself in the emergence of a delayed response of the system to the propagation of the strain‐related perturbations, which is characteristic of media with relaxation or memory. The governing nonlinear dispersive‐dissipative equations describing the elastic displacement wave were derived with allowance made for the values of the relaxation parameter. The influence of the generation and relaxation of lattice defects on the propagation of this wave was analyzed. It is shown that, for short relaxation times of defects, the strain wave can propagate in the form of shock fronts. In the case of longer relaxation times, shock waves do not form and the strain wave propagates only in the form of solitary waves or a train of solitons. The contributions of the finiteness of the defect‐recombination rate to the linear and nonlinear elastic modulus, and lattice dissipation and dispersion parameters are found. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)