斜裂纹定量检测的全光学检测技术研究

Total optical detection technology for quantitative detection of oblique crack

该文采用有限元仿真方法分析斜裂纹与激光超声表面波的作用机理。主要研究内容包括:通过建立斜裂纹与激光超声作用的二维仿真模型,分析裂纹处透射波声场的频谱特征;并对不同深度、不同角度、不同宽度的斜裂纹进行仿真计算,实现采用透射系数对斜裂纹几何参数的分析。研究结果表明:激光超声表面波透射系数随斜裂纹深度呈线性变化,深度越大,透射系数越小,且这种变化与倾斜角度无关。同时,当斜裂纹深度大于0.5 mm且倾斜角度在45°~90°和90°~135°范围内,此时透射系数与倾斜角度呈线性关系。此外,透射系数随着裂纹宽度的增大而减小,且这种变化与深度、倾斜角度无关。该文研究结果可为激光超声定量检测斜裂纹的深度、宽度与角度提供有力的仿真研究参考。

The mechanism of action between oblique crack and laser ultrasonic surface wave is analyzed by finite element simulation method. The main research contents including: by establishing a two-dimensional simulation model of oblique crack and laser ultrasonic action, the spectral characteristics of the transmitted waves field at the crack are analyzed. The oblique cracks with different depth and angle are simulated, and the geometrical parameters of cracks are analyzed by means of transmission coefficients. The results show that the transmission coefficients of laser ultrasonic surface wave changes linearly with the depth of oblique crack, and the greater the depth, the smaller the transmission coefficient, and this change is independent of the tilt Angle.At the same time, when the depth of the oblique crack is greater than 0.5 mm and the tilt angle is within the range of 45°-90° and 90°-135°, the transmission coefficients are linearly related to the tilt angles. Besides, the transmission coefficient decreases with the increase of width, and this change is independent of the tilt Angle and depth. The results of this paper can provide a powerful reference for the simulation of laser ultrasonic quantitative detection of the depth and angle of oblique cracks.