Non-contact measurement of nonlinear Rayleigh waves using the scanning laser vibrometer

Abstract

This paper describes an experimental methodology for the generation and measurement of nonlinear Rayleigh waves in thick plates. A high-voltage ultrasonic transducer together with a polyethylene wedge is used to generate the surface waves in the specimen. The Polytec PSV-400-M2-20 scanning vibrometer system is used to make non-contact, full-field measurements of the out-of-plane displacement of the plate. Results for the growth of the second harmonic amplitude with propagation distance and the relative nonlinearity parameter are presented. The effects of surface preparation and averaging of the time domain signal on the consistency of the second harmonic measurements are investigated.