New evolution equations for the nonlinear surface acoustic waves on an elastic solid of general anisotropy

New evolution equations for the nonlinear surface acoustic waves in anisotropic media are derived in the frame of the second-order elasticity theory. The proposed theory explicitly accounts for the possible significant difference of the depth structure of the nonlinear surface acoustic waves with the depth structure of the linear surface acoustic waves. The derived equations reduce to the form, recently obtained for the nonlinear Rayleigh surface acoustic waves in isotropic solids, when two partial waves (contributing to the surface acoustic wave propagating along a crystal axis in the basal plane of a cubic crystal) exhibit purely exponential decay in depth.