Experimental observations of nonlinear effects of the Lamb waves

作     者：DENGMingxi D.C.Price D.A.Scott 

作者机构：LogisticsEngineeringUniversityChongqing400016 CSIROTelecommunicationandIndustrialPhysicsNSWAustralia 

出 版 物：《Chinese Journal of Acoustics》 (声学学报（英文版）)

年 卷 期：2004年第23卷第3期

页      面：226-243页

学科分类：07[理学] 082403[工学-水声工程] 08[工学] 070206[理学-声学] 0824[工学-船舶与海洋工程] 0702[理学-物理学] 

基　　金：the National Natural Science Foundation of China(10004016) 

主　　题：Experimental observations of nonlinear effects of the Lamb waves MHz 

摘      要：The experimental observations of nonlinear effects of the primary Lamb waves have been reported. Firstly, the brief descriptions have been made for the nonlinear acoustic measurement system developed by Ritec. The detailed considerations for the acoustic experiment system established for observing of the nonlinear effects of the primary Lamb waves have been carried out. Especially, the analysis focuses on the time-domain responses of second harmonics of the primary Lame waves by employing a straightforward model. Based on the existence conditions of strong nonlinearity of the primary Lamb waves, the wedge transducers are designed to generate and detect the primary and secondary waves on the surface of an aluminum sheet. For the different distances between the transmitting and receiving wedge transducers, the amplitudes of the primary waves and the second harmonics on the sheet surface have been measured within a specified frequency range. In the immediate vicinity of the driving frequency, where the primary and the double frequency Lamb waves have the same phase velocities, the quantitative relations of second-harmonic amplitudes with the propagation distance have been analyzed. It is experimentally verified that the second harmonics of the primary Lamb waves do have a cumulative growth effect along with the propagation distance.