Nonlinear propagation of narrow-band Rayleigh waves excited by a comb transducer

Quantitative experiments have been performed to measure the harmonic generation of narrow-band Rayleigh waves in aluminum. Based on a comparison of several methods, the Sokolinskii comb transducer was selected as an excitation source. Results are presented for narrow-band Rayleigh waves (center frequency 9.85 MHz) generated by the comb and detected with a path-stabilized Michelson interferometer. The on-axis, out-of-plane displacement amplitude was measured as a function of distance from the source. Maximum out-of-plane displacements greater than 7 nm were observed. An existing quasilinear theory that included both diffraction and attenuation was used to interpret the data. Values of the nonlinearity parameter β11= 0.21–0.23 predicted displacements in good agreement with the data and were consistent with values for β11 calculated from literature values of the third-order elastic moduli of aluminum.