双层杆结构中纵向模态的超声导波

通过分析应力和位移边界条件得到了双层杆结构中纵向模态的频散方程，并进行数值求解，得到相应的频散曲线。对该结构中纵向模态的主要传播特性进行了分析。然后，利用长度伸缩型压电陶瓷片在内层为冰外层为钢的双层杆结构中进行了激励接收纵向模态的实验。实验结果与理论分析较为吻合。结果表明，双层杆结构的频散曲线可用作模态选取的理论指导，用于该结构的缺陷检测。

Longitudinal mode of ultrasonic guided waves in two layered rod

Dispersion equation of longitudinal modes in two layered rod is obtained by means of analyzing the boundary conditions of stress and displacement of the structure and solving numerically. As a result, longitudinal mode dispersion curves of the structure are shown. Main propagation characteristics of longitudinal modes are analyzed. Exciting and receiving longitudinal modes in a two layered rod of which the inner and the outer layer are respectively ice and steel are carried out using length-expander piezoelectric elements. Experimental studies are in close agreement with theoretical expectation. Results show that the dispersion curves can afford theoretical guidance for mode choice for defect detection in an arbitrary two layered rod.