Effect of interfacial properties on Stoneley wave propagation

Several authors have shown analytically that Stoneley waves may propagate along the interface between certain materials; however, few attempts have been made to utilize these waves for nondestructive evaluation. This paper reports the results of an effort to develop a technique for nondestructive interface characterization of composite materials which exploits the unique characteristics of these waves. Consequently, ultrasonic Stoneley waves were generated at a contact interface and their sensitivity to several interfacial parameters was measured. The interface between Ti-6Al-4V and 4340 steel was altered by microstructural modification, by varying the surface finish and by varying the contact pressure. These parameters were manifested as measured velocity changes of a Stoneley wave which was generated and detected by a Rayleigh mode conversion technique. The results indicated that Stoneley waves are sensitive to microstructural changes and interface quality.