基于有限元方法的双层材料激光超声数值模拟

Numerical Simulation of Laser Induced Ultrasound in Double Layer Materials Based on Finite Element Method

采用有限元方法数值模拟了单脉冲激光热弹激发双层材料中的超声波,得到了材料的上下表面的应力场分布。通过对铝板中的波形进行快速傅里叶变换得到频率信号,计算出波包群速度,判断出材料中兰姆波的模态。结果表明:受基底影响,在双层材料的上层铝板中得到了三种模态的兰姆波。该研究为复合材料激光超声的应用研究提供了新的途径。

The thermoelastically generated ultrasound in double layer materials was numerically simulated by finite element method（FEM）, and the stress field on top and bottom surface was obtained. Then, the frequency signal from the waveform of stress was obtained by using FFT, according to the group velocity of the ultrasonic packet so that the modes of Lamb wave in the materials could be found out. The results showed that three kinds of modes of Lamb wave influenced by the substrate were fount in aluminum plate of the double layer materials. The results could provide a new approach for the research of the laser induced ultrasound in composite material.