Observation of flexural Lamb waves (A(0) mode) on water-filled cylindricalshells

Results are presented for the propagation of circumferential acoustic waves around a thin-walled stainless steel tube. Sol gel lead titanate-zirconate (PZT) films and chirp interdigital transducer (IDT) electrodes were used t o generate the A(0) mode from 0.8 to 6.0 MHz. Group and phase velocity meas urements are in good agreement with the theory for the empty tube. When the tube is filled with water a large decrease of 21% in group velocity is obs erved. While there is as yet no theoretical explanation for this effect, th e results show promise for liquid sensing applications. (C) 1998 Acoustical Society of America. [S0001-4966(98)00612-2].