【摘要】 提出了一种无损探测材料表面微小缺陷的新方法,利用移动扫描激光线源在材料表面激发的超声瑞利波,结合自行改进的差分式光偏转探测系统接收该超声波信号,并对该探测系统的测试原理进行了讨论;在利用系统进行实验研究时观察到:当激发激光源接近材料表面的人工缺陷时,探测信号的幅度会发生显著变化.通过对信号幅度变化规律的特征分析,可以对材料表面的微小缺陷进行诊断,亦证实了扫描激光线源技术在材料表面微小缺陷无损检测方面具有的应用价值.更多还原

【Abstract】 A new nondestructive surface micro-crack detection method is presented in this paper.Ultrasonic Rayleigh waves are induced by the scanning laser line source(SLLS) on the surface of a sample and the ultrasonic signals are detected by a self-developed differential optical beam deflection(OBD) detection system,whose detection principle is also discussed in detail.In the experiment we observed that the amplitude of the detected signals changed apparently when the laser source reached the edge of an artificial notch.The analysis of the change of the signals shows that the change rule can be applied to the detection of the micro cracks on sample surface.The results have proved the application value of the SLLS technology in nondestructive crack detection.更多还原