Analysis of Nonlinear Rayleigh Surface Wave Fields Generated by Comb Transducers

Comb transducers can be considered to effectively generate nonlinear Rayleigh surface waves, including second harmonics. In this paper, we calculate the propagation and reception fields for the fundamental and second harmonics of Rayleigh surface waves generated by the finite-amplitude excitation of a comb transducer composed of single and multiple line sources. The sound fields of the comb transducer with multiple line sources are formulated by extending an existing single-line source model, and the received sound fields are calculated for three different types of receivers, namely the point, single line, and multiple line reception. In addition, nonlinear parameters of the surface waves, which are calculated from the amplitudes of the fundamental and second harmonics, are defined, and accompanying diffraction and attenuation correction equations are obtained and the results are presented. The analysis presented in this paper can be used for the quantitative measurement of nonlinear parameters of materials using comb transducers.