激光在管道中激发周向导波的有限元模拟

Finite element simulation of laser-generated circumferential waves in hollow cylinder

以超声的热弹激发机理为基础,建立了模拟激光在管道中激发周向导波的有限元模型.为了验证模型的正确性,根据Gao等人报道的实验条件[J.Appl.Phys.91,6114(2002)]进行了模拟,理论模拟结果与Gao等人的实验结果符合很好,说明本数值模型的正确性.在此基础上,模拟激光在不同厚度、不同曲率半径的管道内激发的周向导波波形,同时分析了激光在管道中激发的周向导波波形与平板中激发Lamb波的差异,以及管道厚度和曲率半径对激光激发周向导波的影响.

Based on the thermoelastic mechanism of laser ultrasonic, a finite element model for simulating laser-generated circumferential wave in a hollow cylinder is developod. A control calculation is executed to verify the correctness of the model according to the study of Gao et al （ J. Appl. Phys. 91, 6114 （2002））. Our calculated results are in good agreement with the experimental signals obtained by Gao et al. And then, the circumferential waves induced by line laser source in hollow cylinders with different thicknesses and different radii are simulated and typical results are presented. Based on the numerical calculations, the difference between circumferential guided waves in hollow cylinder and Lamb waves in a plate, and the influence of the thickness and radius on the circumferential waves are discussed in detail.