Numerical and Experimental Evaluation of Ultrasonic Wave Propagation Characteristics at Contact Interface

Abstract

As a background of the ultrasonic characterization of contact interfaces, ultrasonic wave propagation characteristics at contacting solid surfaces have been studied numerically and experimentally. The wave propagation along the contact interface has been simulated by the two-dimensional finite difference method, assuming a spring-type interface with normal and tangential stiffnesses. The analysis has verified that the antisymmetric-mode interface wave can be generated by the shear excitation at one end of the interface, and its phase velocity can be evaluated with good accuracy from the waveform received at the other end. Measurement of the phase velocity of the interface wave has been carried out for contacting PMMA surfaces under different contact pressures, together with the shear-wave reflection measurement to evaluate the interface tangential stiffness. The measured relation between the phase velocity and the tangential stiffness has been shown to agree well with the theoretical relation for the antisymmetric-mode interface wave.