基于比例边界有限元法的Lamb波在板中传播的模拟分析

基于比例边界有限元法对Lamb波在板中遇到多裂纹、内置竖向和横向裂纹以及凹陷时的传播行为进行模拟,在入射波模态为S_0和A_0这2种情况下,改变内置裂纹的开裂角与深度、凹陷的弧度,对反射波的模态振幅进行分析。研究表明,在同一薄板上,不同的裂纹形态对于波形的增幅有所不同。反射波的模态振幅随着裂纹深度与开裂角的增大基本呈增大趋势,Lamb波的激发模态为A_0时,随着板中内置裂纹开裂角的增大,反射波模态振幅的增大效果与激发模态为S_0时相比更为明显。当激发的入射波模态为S_0时,反射波中的模态振幅随着板上凹陷的减缓,减小幅度更大。

Simulation of Lamb wave propagation in plate based on the scaled boundary finite element method

Based on the scaled boundary finite element method, the propagation behavior of Lamb waves in a plate encountering multiple cracks, built-in vertical and transverse cracks, and depression was simulated. Different cracking angles, depths of the built-in crack and curvatures of pit were simulated under the A₀ and S₀ excitation mode, in which the mode amplitude of the reflected wave were analyzed. On the same plate, different crack pattern will have different increment for the waveform. The mode amplitude of the reflected wave increases with the increase of the crack depth and the crack angle. As the cracking angle of built-in crack increases, the effect of the mode amplitude in reflected waves is more obvious when the excited mode is antisymmetric A₀ mode. The mode amplitude in the reflected wave decreases as the depression on the plate slows down, which is more obvious when the excited mode is symmetric S₀ mode.