厚壁筒形件的周向超声检测过程中, 超声波对内表面径向缺陷检测的灵敏度受到多种因素的影响。常规的超声检测技术存在灵敏度低、缺陷定位困难等难点; 采用聚焦技术可提高检测的灵敏度, 但横波接触聚焦法的检测范围受曲面和声场结构等因素限制。采用柔性超声相控阵聚焦技术, 根据曲面形状设计聚焦法则, 可以有效地解决厚壁筒形件径向缺陷超声检测的技术难题。试验结果表明: 提出的柔性相控阵聚焦技术对厚壁筒形件内表面径向缺陷具有较高的检测信噪比。

When circumferential ultrasonic testing is performed for thick walled cylindrical item, the testing sensitivity of internal surface radial defects is affected by various factors. The conventional circumferential ultrasonic testing could not receive satisfied performance because of its low sensitivity and of difficulty in locating defects. The testing sensitivity of internal surface radial defects can be improved by ultrasonic focusing technique. However, the contact transverse wave ultrasonic focusing technique is limited by various factors such as curved interface and sound-field structure. A flexible phased array technique is performed in the paper, and a flexible probe is designed which can be in good match to the surface of thick walled cylindrical item. The focal law is designed based on the curved shape and can effectively solve the difficult testing problem of internal surface radial defects of thick walled cylindrical item. The experimental results show that the flexible phased array technique has high signal to noise ratio for detecting internal surface radial defects of thick walled cylindrical item.