激光脉冲线源位移场的数值与实验研究

Numerical and experimental study on the ultrasonic displacement field generated by a laser pulse line source

采用Fourier变换方法求解激光脉冲线源作用下弹性介质中的波动方程，获得了位移解的积分表达式，直接采用两次FFT方法数值计算了位移波形。所计算的情况包括铝介质半无限空间表面位移、铝板的背中心及编中心表面位移。激发源分别考虑热弹和烧蚀两种情况。实验则采用脉冲Nd：YAG激光进行激励并使用激光干涉仪进行检测。比较数值结果与试验结果两者有较好的一致性。

Applying the Fourier transform to the wave equations of elastic medium at its surface a laser pulse line sourceis acted, the integral representations of solutions are obtained. Displacemellt wavforms are ca1culated by using doubleFFT. The calculated results include the displacements of the elastic half space of Aluminum medium, and epicenter andoff-epicenter of an Aluminum plate. The two exciting souxces of thermoelastic and ablating generation are consideredrespectively. The experimeot was made on the Aluminum medium with a Nd: YAG laser and the normal displacementsignals are detected by a laser interferometer. The numerical results are quite in agreement with experiments.