【作者】 陈友兴；

【导师】 王召巴；

【作者基本信息】 华北工学院 ， 测试计量技术及仪器， 2004， 硕士

【摘要】 目前，超声检测作为一种常用的无损检测技术被广泛的应用于航空航天、核工业、石油及其它民用领域的粘接结构检测中。对于多层钢/橡胶交替层叠而成的粘接结构，由于钢和橡胶之间的声阻抗差异较大，用常规的超声检测技术很难满足检测要求。本文以火箭发动机柔性接头部件为对象，分别采用板波和纵波两种检测技术，研究多层粘接结构脱粘超声检测技术及其信号处理。本文首先分析了板波诱发纵波在柔性接头构件中的传播规律，对原始回波信号进行时域和频域分析。在此基础上，提出了常数分离法和自适应分离法，分别用它们分离板波回波信号中的各界面回波，利用小波多分辨率分析提取原始回波信号的特征和BP神经网络进行模式识别。文章还尝试了纵波检测技术检测这种构件，得出了用双探头穿透法可以判定是否存在界面脱粘，用自适应滤波对直探头检测的回波进行处理，所得结果反应了各界面脱粘回波的特征。实验证明，用以上两种检测技术都能很好的检测这种构件的界面粘接状态，综合应用它们可以对构件进行全面、有效的检测。更多还原

【Abstract】 Ultrasonic testing, one of the common nondestructive testing technologies, is widely used in aerospace, nuclear, petroleum industry and other fields for defects in the adhesive structure. It is difficult to detect interface debond in the adhesive multi-layered steel-rubber structure through the common ultrasonic testing due to the considerable acoustic impedance differences of between the steel and the rubber. The ultrasonic testing and signal processing for bonded defects in the structure of flexible joint of the solid rocket motors are studied. And the Lamb Wave method and the Longitudinal Wave method are used in the ultrasonic testing.The transmission rule of the lamb wave in the structure of the flexible joint is discussed, and the ultrasonic pulse echo is analyzed in the time-field and frequency-field. The Constant-separate method and the Adaptive-separate method based on the above ultrasonic principle are used to separate each interface-echo in the ultrasonic pulse echo. The feature of the each ultrasonic pulse echo is gained through the wavelet transformation, and is identified through BP neural network.The Longitudinal Wave method for testing the structure is also discussed. It is found that the bi-sensor method can determine whether the structure has interface debond. Then the adaptive filtering is adopted in the signal processing for the echo through single-sensor. Based on the above results, the feature of each interface echo is gained. It is shown by experiments that the Lamb Wave method and the Longitudinal Wave method are both capable of detecting the adhesive state of the structure. The detection of the structure becomes more comprehensive and effective if the above two methods ate employed in combination.更多还原