基于激光超声的金属表面裂纹定位研究

Research on metal surface crack location based on laser ultrasound

激光超声技术以其高精度、非接触和宽频带的特性被广泛应用于金属表面裂纹检测,但对于金属表面任意角度裂纹地检测和识别还有待于深人研究。通过研究金属表面不同角度裂纹反射回波的时域特性,发现合理地布置测量激光可以检测[0°,90°)范围内的表面裂纹,并且裂纹反射回波的时间与裂纹的角度存在一定的函数关系。在此基础上优化了测量模型并推导出了裂纹角度与裂纹反射回波时间之间的函数关系,然后进行了实验验证。结果表明,所提出的裂纹角度的计算方法可以准确地判断激光超声与金属表面裂纹的夹角,并且测量误差小于1°的概率为71.25%。为金属表面任意走向裂纹的检测与定位提供了理论依据。

Laser ultrasonic technology is widely used for the detection of metal surface cracks with its high precision,noncontact and broadband characteristics.However,the detection and identification of metal surface cracks at any angle remains to be further studied.In this paper,we study the time-domain characteristics of crack reflection echoes at different angles on metal surfaces,and finds that Reasonably arranging the measuring laser can detect surface cracks in the range[0°,90°)and the time of the crack reflection echo has a certain functional relationship with the angle of the crack.On this basis,the measurement model is optimized and the function relationship between crack angle and crack reflection echo time is derived,and then experimental verification is carried out.The results show that the method of calculating the crack angle can accurately determine the angle between laser ultrasonic and metal surface cracks,the probability of a measurement error less than l°is 71.25%,and provide a theoretical basis for the detection and location of arbitrary surface cracks on metal surfaces.