声表面波检测铝板表面微缺陷深度实验研究

为了探究声表面波与不同深度微裂纹缺陷相互作用的关系,将脉冲激光作用于一系列不同缺陷的试件铝板上进行线光源激励,激发激光超声波。用超声传感器接收在铝板中传播的激光超声信号,通过数字荧光示波器采集激光超声在铝板中的传播数据。对采集到的反射波数据进行分离谱分离过程得到的铝板中激光超声的时域分布和透射波数据进行频域分析。实验发现:缺陷深度影响着反射回波两峰值特征点到达时间差,两者之间近似线性关系,也影响着透射波的截止频率且二者呈现递减关系。

Experimental study on depth evaluation of micro-surface crack by laser generated acoustic surface waves

With a laser in a range of different flaw test pieces on an aluminum plate fires laser ultrasonic, perform continuous line source excitation by a pulsed laser, receives the laser ultrasonic signal in aluminum plate with ultrasonic sensors, get laser ultrasonic propagation data in aluminum with digital phosphor oscilloscope .The collected data transmitted wave frequency domain analysis and the reflected wave data split-spectrum processing obtained laser ultrasonic signal temporal distribution in aluminum. Turn out,defect depth affects the reflection echo peak two feature points difference in arrival time, there are approximately linear relationship between the two. the cut-off frequency of the transmitted wave spectrum with defect depth change presents certain rules, defect depth and transmitted wave cut-off frequency is also approximately linear relationship.