台阶板中兰姆波A0模式传播特性的光弹研究

为了研究变壁厚结构中兰姆波的传播特性，以K9玻璃制成的台阶板为波导，运用动态光弹法实现了兰姆波在阶梯板中传播过程的可视化。使用MATLAB对兰姆波的理论应力分布进行了仿真，将仿真结果与光弹图像相对比以进行模式识别。此外，根据兰姆波的动态光弹图像计算了特定模式的相速度，并与相速度频散曲线相对比，以支持模式识别的结果。对4mm-3mm和4mm-2mm厚度差台阶板进行了对比分析。研究发现在激励目标模式的兰姆波时，可能会出现非目标模式，并且兰姆波的模态转换与频散程度与台阶处的厚度差有关。本文的结果可对具有相同性质类似结构材料的无损检测提供参考。

Study on propagation characteristics of asymmetric Lamb mode in thickness variation plate

To study the propagation characteristics of the Lamb wave in the variable wall thickness structure, the step plate made of K9 glass was used as the waveguide. The dynamic photoelastic method was used to realize the visualization of the Lamb wave propagation process in the step board and the stress distribution of the mode of lamb wave was simulated by MATLAB. The simulation results were compared with the photoelastic image for pattern recognition. Besides, the phase velocity of the specific mode was calculated according to the dynamic photoelastic image of the Lamb wave. The calculation results were compared with the phase velocity dispersion curve to support the result of pattern recognition. The 4mm-3mm step board and the 4mm-2mm step board were compared analysis. It is found that when the Lamb wave of the target mode is excited, a non-target mode may occur, and the degree of dispersion and mode conversion of the Lamb wave is related to the difference in thickness at the step. The results of this paper can provide reference for non-destructive testing of similar structural materials with the same properties.