相比于电磁超声检测方法, 脉冲涡流检测方法对于近表面缺陷具有较高检测灵敏度。而电磁超声信号本身包含脉冲涡流信号部分, 基于此特点, 开发了电磁超声/脉冲涡流的复合无损检测方法。首先, 基于有限元理论开发了电磁超声/脉冲涡流复合信号的数值模拟方法; 其次, 提出了基于频谱分析、滤波等策略对混合检出信号进行信号分离提取的方法, 并结合试验验证了所提方法的有效性; 最后, 基于复合检测方法对铝板中的三种类型缺陷(表面缺陷、底部减薄缺陷、复合缺陷)同时成功地进行了检测, 验证了所开发复合检测方法的优越性。

EMAT (Electromagnetic Acoustic Transducer) testing method is of the inherent disadvantage of the near surface blind area. On the other hand, the pulsed eddy current testing (PECT) method has higher inspection sensitivity for near surface defects. After analysis, we find that actually the EMAT testing signal itself contains the PECT part. Based on the backgrounds above, the purpose of this study is to propose a hybrid NDT method which is to combine PECT with the EMAT together. The contents of this paper are as follows: firstly, a numerical code is developed for the simulation of hybrid EMAT/PECT signals based on finite element method; then, signal separation and extraction methods are proposed on the basis of the spectral analysis and filtering strategies for signals of the hybrid EMAT/PECT method and investigated by experiment. Finally, the three types of defects (surface defects, bottom thinning defects, composite defects) in aluminum plate are successfully detected at the same time based on the developed hybrid NDT method, which validates the superiority of the developed hybrid PECT/EMAT NDT methods.