Guo Yizhou, Hu Yu, Wang Kai, Song Yini, Feng Bo, Kang Yihua, Duan Zhaoqi
School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Sensors (Basel). 2024 Aug 11;24(16):5196. doi: 10.3390/s24165196.
During electromagnetic ultrasonic testing, it is difficult to recognize small-size bottom cracks by time of flight (ToF), and the lift-off fluctuation of the probe affects the accuracy and consistency of the inspection results. In order to overcome the difficulty, a novel composite sensor of an electromagnetic acoustic transducer (EMAT) and pulse eddy current (PEC) is designed. We use the amplitude of a bottom echo recorded by EMAT to identify the tiny bottom crack as well as the amplitude of PEC signals picked up by the integrated symmetric coils to measure the average lift-off of the probe in real time. Firstly, the effects of lift-off and bottom cracks on the amplitude of bottom echo are distinguished by combining the theoretical analysis and finite element method (FEM). And then an amplitude correction method based on the fusion of EMAT and PEC signals is proposed to reduce the impact of lift-off on the defect signal. The experimental results demonstrate that the designed composite sensor can effectively detect a bottom crack as small as 0.1 mm × 0.3 mm. The signal fusion method can accurately correct the amplitude of defect signals and the relative error is less than ±8%.
在电磁超声检测过程中，很难通过飞行时间（ToF）识别小尺寸的底部裂纹，并且探头的提离波动会影响检测结果的准确性和一致性。为了克服这一困难，设计了一种新型的电磁超声换能器（EMAT）与脉冲涡流（PEC）的复合传感器。我们利用EMAT记录的底部回波幅度来识别微小的底部裂纹，并利用集成对称线圈拾取的PEC信号幅度实时测量探头的平均提离。首先，结合理论分析和有限元方法（FEM）区分提离和底部裂纹对底部回波幅度的影响。然后提出一种基于EMAT和PEC信号融合的幅度校正方法，以减少提离对缺陷信号的影响。实验结果表明，所设计的复合传感器能够有效检测出小至0.1 mm×0.3 mm的底部裂纹。信号融合方法能够准确校正缺陷信号的幅度，相对误差小于±8%。
