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研究激光激发瑞利波检测样品的表面倾斜缺陷。基于频域热弹耦合方程,采用有限元方法建立激光激发瑞利波检测倾斜缺陷的数值模型,研究倾斜缺陷的检测机理。数值计算含不同的长度及倾斜角度缺陷的样品中瞬态位移波形,分析瑞利波在倾斜缺陷处模式转换的过程,研究各种瑞利波的传播路径。在此基础上,研究缺陷宽度与材料黏性对瑞利波传播及缺陷检测的影响。结果表明:瑞利波在缺陷处产生的反射及透射瑞利波的到达观测点的时间可以检测缺陷位置和长度,瑞利波在缺陷的底部发生模式转换产生的切变波可以检测缺陷倾斜角度。数值结果和已有的实验结果一致,从而为表面倾斜缺陷的检测提供有效的理论依据。
Study laser-induced Rayleigh wave detection of surface tilt defects. Based on the frequency-domain thermo-elastic coupling equation, a numerical model of laser-induced Rayleigh wave detection of tilt defects was established by finite element method and the detection mechanism of tilt defects was studied. The transient displacement waveforms in the samples with different length and tilt angle defects are numerically calculated. The mode transitions of Rayleigh waves at oblique defects are analyzed, and the propagation paths of various Rayleigh waves are studied. Based on this, the influence of defect width and material viscosity on Rayleigh wave propagation and defect detection was studied. The results show that the Rayleigh wave can detect the position and length of the reflection when the Rayleigh wave is generated at the defect and the time when the transmitted Rayleigh wave reaches the observation point. The shear wave generated by the mode conversion of the Rayleigh wave at the bottom of the defect can detect the defect tilt angle . The numerical results agree well with the existing experimental results, so as to provide an effective theoretical basis for the detection of surface tilt defects.