Abstract
The influence of the contact pressure on the ultrasonic wave propagation along the contact interface between two solids has been studied experimentally. In this study, the contact interface wave is generated and received for mated polymethyl methacrylate (PMMA) blocks, aluminum blocks and copper blocks under different contact pressures. The measurement has shown that the propagation velocity of the contact interface wave increases from the Rayleigh wave velocity to the bulk shear wave velocity as the contact pressure is increased. Spectral analysis has been performed to obtain the phase velocity of the contact interface wave as a function of the frequency and the contact pressure. The tangential stiffness of the interface has been also identified, which is shown to increase as the contact pressure is increased. The contact interface wave velocity and the interface stiffness are found to be very sensitive to the contact pressure, and expected to offer a promising possibility to evaluate the contact conditions nondestructively.
