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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.
In order to solve the problem that the coupling agent can not be applied on the surface of the solid rocket motor housing during the ultrasonic testing, a set of dry-coupled ultrasonic testing system is first constructed and the dry coupling of the piezoelectric vibrator and the sounding rod with special structure is designed Then a time-reversed-based dry-coupled ultrasound imaging method is proposed to analyze the time-reversed focusing principle of dry-coupled ultrasound, and the transient fluctuations at the focusing time are established by extracting the damage scattering signal, At last, the defects are imaged by summing the products of the amplitude of the signal of the structure micro-signal, the test results show that the method can detect the debonding defect in the bonding structure and basically determine the shape and the position of the defect.