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分别从理论和实验上研究了脉冲激光在快、慢镀层圆柱表面激发的表面波声场。脉冲激光线源在镀层圆柱周向上激发超声波信号并利用激光干涉仪检测。对钢基底锌镀层圆柱和锡基底铜镀层圆柱试样表面波的理论频散和实验信号估计频散进行了比较,瞬态位移场则利用留数定理与FFT技术数值仿真得到并与实验波形进行对比。结果显示:理论频散和仿真波形与实验信号都具有极好的一致性,而快、慢镀层圆柱之间的表面波性质有显著差异。文中所用理论分析和数值方法为使用激光超声技术反演和定量表征镀层材料参数等无损检测技术奠定了理论基础。
The surface acoustic wave field excited by the pulsed laser on the surface of the fast and slow-coated cylinders is studied theoretically and experimentally. The pulsed laser source excites the ultrasonic signal in the circumferential direction of the coated cylinder and detects it with a laser interferometer. The theoretical dispersion and experimental signal dispersion of the experimental samples are compared with the theoretical dispersion of the surface of the steel substrate and the copper substrate and the transient displacement field is obtained by using the theory of residuals and the numerical simulation of the FFT technique. Compared. The results show that the theoretical dispersion and the simulation waveforms are in good agreement with the experimental signals, while the surface wave properties between the fast and slow-coated cylinders are significantly different. The theoretical analysis and numerical methods used in this paper have laid the theoretical foundation for the non-destructive testing techniques such as inversion and quantitative characterization of coating material parameters by using laser ultrasonic technique.