搭建了光纤光栅检测超声应力波系统, 并阐述其工作原理, 以动态应变与光纤光栅中心波长漂移量间关系为基础, 推导得出输出电压与板中应变成线性关系.采用超声信号发生器发射28 kHz的脉冲信号激励超声振子, 通过有机玻璃楔形块将激励传递至5052铝合金薄板产生超声应力波, 并利用光纤光栅应变传感器对其进行探测.在板上开一98 mm长裂缝, 测得超声应力波中出现新的波包, 通过计算损伤前后新增波包到来的时间差确定裂缝位置, 所测结果与实际位置偏差为2.7 mm.该实验表明光纤光栅可代替超声探头来实现对低频超声波的探测.

A detection system of ultrasonic stress wave based on fiber Bragg grating was established, whose working principle was expressed. The linear relationship between the output voltage and plate strain based on the connection between the dynamic strain and center wavelength shift of fiber Bragg grating was derived. A pulse of 28 kHz generated by ultrasonic signal generator drived the ultrasound vibrator, the signal was conveyed to a 5052 aluminum alloy plate through a organic glass wedge to generate stress waves which were detected by a fiber Bragg grating strain sensor. After that, a new wave packet appeared in the measured ultrasonic waves when there was a crack of 98 mm in the plate. The arriving time difference between the new wave packet before and after the damage can be used to determine the crack location. The position deviation of the crack is 2.7 mm. It is shown that instead of an ultrasound probe, the fiber Bragg grating can be used to detect the low-frequency ultrasound waves.