时间反转的固体火箭发动机干耦合超声检测

摘要

To solve the problem that the couplant can ’ t be used on the surface of SRM shell bonding structure in ultrasonic detection, a dry⁃coupled ultrasonic detection system is built, and then special⁃structure piezoelectric vibrator and transmission rod are designed for dry⁃coupled probes. Based on the time reversal, a dry⁃coupled ultrasonic imaging method is proposed and the time reversal principle is analyzed. The transient fluctuation chart on the focus moment is established by extracting damage scatter signals, time reversal and secondary loading. Finally, the defect images are obtained by two methods, including the sum and the product of the amplitudes of signal elements. The experiment shows that the proposed method is valid to detect the shape and the position of the defect in bonding structure.%为解决超声检测过程中不能在固体火箭发动机壳体粘接结构表面涂抹耦合剂的问题，首先构建了一套干耦合超声检测系统，设计了具有特殊结构形式压电振子和传声杆的干耦合探头。然后提出基于时间反转的干耦合超声成像方法，分析干耦合超声时间反转聚焦原理，通过对损伤散射信号的提取、时间反转及二次加载，建立聚焦时刻的瞬态波动图，最后通过对结构微元信号幅值求和乘积两种方式对缺陷进行成像。试验结果表明，该方法能够检测出粘接结构中的脱粘缺陷，基本确定缺陷的形状及位置。