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单端激励与接收方式的超声导波管道检测信号,经过管道中缺陷处和管道端头时会产生多次来回反射和透射,直到信号功率流耗尽为止,这种多次来回反射和透射过程导致了超声导波伪缺陷信号的出现,而伪缺陷信号的存在严重影响了对管道检测中缺陷数量和位置的判别.针对伪缺陷信号识别难点问题,绘制超声导波在管道中传播路径示意图,归纳总结出超声导波检测伪缺陷信号出现的位置特征规律,即:第1个反射周期检测信号中不会出现伪缺陷信号或其信号幅值很小可忽略,较大幅值的伪缺陷信号从第2个反射周期检测信号开始出现并与真实缺陷信号关于该周期内检测信号的时域中点对称,并采用数值模拟方法和实验检测验证了该规律的正确性.依据伪缺陷信号出现的特征规律,对超声导波管道检测信号中缺陷波包信号进行识别和提取,并利用匹配追踪方法和数值比对赋值法对伪缺陷信号进行消除.研究结果表明:提出的超声导波管道检测伪缺陷识别及其消除方法行之有效,实现了超声导波检测缺陷信号去伪成真目的,解决了超声导波检测信号识别难点问题,极大促进了超声导波无损检测技术的工程应用.
Single-ended excitation and reception of the ultrasonic guided wave detection signals through the pipe defects and pipeline ends will produce multiple back and forth reflection and transmission until the signal power flow depleted so far, this multiple back and forth reflection and transmission process Resulting in the emergence of ultrasonic guided wave pseudo-flaw signal, and the existence of false-flaw signal has seriously affected the determination of the number and location of defects in pipeline inspection.Aiming at the difficulty of identifying the false-flaw signal, drawing the schematic diagram of the propagation path of ultrasonic guided wave in the pipeline, Summarizes the ultrasonic guided wave detection of pseudo-defect signal appearance characteristics of the law, that is: the first reflection period detection signal does not appear false signal or its signal amplitude is small negligible, larger amplitude of the pseudo-defect signal from The second reflection period detection signal begins to appear and is symmetrical with the true defect signal in the time domain about the detection signal in the period, and the correctness of the law is verified by numerical simulation and experimental verification. According to the appearance of the pseudo-defect signal Law, the ultrasonic wave guide pipe detection signal defects in the wave packet signal identification and extraction, and use matching tracking method and numerical ratio The assignment method is used to eliminate the fake signal.The research results show that the method proposed in this paper is effective to identify the fake defect and to eliminate the fake signal in ultrasonic guided wave detection, Wave detection signal recognition difficulties, which greatly promoted the application of ultrasonic guided wave nondestructive testing technology.