针对Lamb波的多模式和频散特性,从理论和实验两方面研究了Lamb波双面激励方法,并针对近邻损伤进行了监测研究。研究结果表明:与传统的单面激励方法相比,该激励方法能够抑制Lamb波的多模式特性,在频率较低的情况下可实现基本对称或反对称模式的产生,提高了Lamb波的激励效果,便于监测信号的分析。另外,相对于通过调节激励频率产生特定Lamb波模式的方法,该激励方法具有一定的频率可调性,能有效改善Lamb波波包的空间分辨率,增强Lamb波对多个近邻损伤的监测能力。
According to the multi-mode and dispersion characteristics of Lamb waves, a double side excitation method is studied in the theory and the experiment to monitor adjacent damages. Results show that, the double side excitation method, compared with the traditional single side one, can inhibit the multi-mode characteristic of Lamb waves and generate fundamental symmetric and antisymmetric modes at the relatively low exciting frequency. It can heighten the exciting effect and make it easy to analyze monitoring signals. Moreover, in contrast to a specific mode generated by adjusting exciting frequency, the exciting frequency is changeable in the double side excitation method, thus improving the spatial resolution of the Lamb wave packet and the ability of adjacent damage monitoring of Lamb waves.