基于独立分量分析的搅拌摩擦焊缝超声无损评价

Ultrasonic nondestructive evaluation of friction stir welding joints based on independent component analysis

指出搅拌摩擦焊焊缝的弱连接是目前超声无损检测的难点.提出了一种新的超声特征成像方法,包括使用独立分量分析方法(independent component analysis,ICA)对时域超声信号进行分解,进而获得检测信号的特征矩阵;根据检测信号能量传递的特点,确定检测目标特征矢量的筛选方法,将检测信号向特征矢量投影,将投影能量和作为特征参数,对搅拌摩擦焊焊缝进行声成像.应用该方法对不同拉伸强度的搅拌摩擦焊焊缝进行了声成像检测,并与常规C扫描方法进行了对比.结果表明,该方法的检测结果与拉伸试验具有较好的一致性,对于搅拌摩擦焊焊缝的检测灵敏度高于常规C扫描方法.

The 'kissing-bond' defect in friction stir welding( FSW) joints is difficult to detect with conventional ultrasonic method. A new ultrasonic feature imaging method was proposed for the problem. The method was composed of these steps: getting feature space of inspecting signal by decomposing time-domain signal with independent component analysis( ICA) method,finding out feature vectors for detecting targets according to energy transfer characteristic in ultrasonic detection,projecting ultrasonic signal to the feature vectors; obtaining feature parameter value by accumulating all the projections,using the feature parameter value to reconstruct the image of FSW joints. This method was used to conduct ultrasonic imaging for FSW joints with different tensile strength,and the images were also compared with ones generated by conventional C scan. The results showed that,inspecting results with this new method had good coherence with tension experiments,and showed a better detecting sensitivity for FSW joints evaluation than conventional C scan.