A new technique for measuring Rayleigh and Lamb wave speeds

A new technique is proposed in this paper to measure Rayleigh and Lamb wave speeds in solid half-spaces and plates. In this technique two transducers are positioned above the specimen in a pitch-catch orientation. The time of flight of the signal from the transmitter to the receiver is recorded. Then the rate of change of this time as the distance between the reflector and the transducer varies is experimentally determined. This rate remains constant when leaky Rayleigh of Lamb waves are generated but it varies when these waves are not generated. Thus surface waves are detected in an indirect manner. An expression is derived to relate the surface wave speed to the signal flight time change rate with the transducer specimen distance. Using this expression Rayleigh and Lamb wave speeds have been accurately determined in isotropic metals and anisotropic composites.