NONDISTORTING WAVE-FORMS OF ELECTROELASTIC SURFACE-WAVES

Using a formulation of nonlinear piezoelectric surface waves (Parker and David, Int. J. Eng. Sci., (1989)) the possibility of waves of permanent form is investigated. For waves travelling in any direction across the material surface, the wave profiles are governed by an integral equation of convolution type. This equation reduces to an infinite set of quadratic algebraic equations when the waveform is periodic. Numerical solutions to truncated sets have been obtained for waves travelling across 'Y-cut' LiNbO3. For each of three electrical boundary conditions have real coefficients when the waves propagate along an 'X' axis. Examples of the resulting (symmetric) wave profiles are presented. Propagation along a 'Z' axis leads to algebraic equations with complex coefficients and to asymmetric waveforms. Computations of the development of disturbances to the nondistorting waveforms show that the profiles may travel without significant alteration over ranges which greatly exceed the equivalent break-up range for sinusoidal waves. © 1990.