Experimental verification of cumulative growth effect of second harmonics of Lamb wave propagation in an elastic plate

Wedge transducers are used to generate and detect the primary (fundamental) waves and second harmonics of Lamb wave propagation on the surface of an elastic plate. The amplitudes of the primary waves and the second harmonics on the plate surface are measured for different separations of the transmitting and receiving wedge transducers. In the immediate vicinity of a driving frequency at which the primary and the double-frequency Lamb waves have the same phase velocities, the quantitative relationships of the second-harmonic amplitudes on propagation distance are analyzed. It is experimentally verified that the second harmonics of primary Lamb waves have a cumulative growth effect with propagation distance. (C) 2005 American Institute of Physics.