缝类缺陷的Lamb波检测

Lamb Waves Testing of Slot Defects

在ST12冷轧板上用线切割加工出不同深度的狭缝来模拟钢板中的缝类缺陷,采用一发一收方式,对缺陷进行Lamb波检测。利用短时傅里叶变换对有无缺陷时采集的时域信号进行了时频分析,有效识别出板中激发的Lamb波模式;将时间中心和频率中心作为数字参量,探讨了缝类缺陷对Lamb波的影响。结果表明,Lamb波信号时间中心的变化与缝类缺陷深度有较好的对应关系。

Slots with different depth were made by WEDM in metal sheet of ST12 to simulate slot-type defects, and the Lamb waves were stimulated by pitch catch method.The time domain signals obtained in the plates with and without defect,respectively,were analyzed in time-frequency domain by Short Time Fourier Transform.The lamb wave modes were recognized successfully,and the effects of slot-type defects on Lamb waves was discussed by the time center and the frequency center as digital parameter.The result showed a good corresponding relationship between slot depth and the time center of the lamb wave.