利用Lyapunov指数实现超声导波检测的实验研究

发布时间：2018-07-24 11:08

【摘要】：利用杜芬方程Lyapunov指数提出了一种敏感的超声导波识别方法,并通过对钢管中导波信号的检测验证了该方法的有效性。首先,对比了输入Hanning窗调制导波信号与纯噪声信号对系统Lyapunov指数的不同影响,给出了利用Lyapunov指数识别弱超声导波信号的基本原理,并确定了检测系统参数。然后,利用压电传感器在3 m长的钢管中激发和接受超声导波,并将实测导波信号输入杜芬检测系统。研究结果表明,Lyapunov指数可以有效地识别出回波信号中是否存在导波信号,而对于噪声信号Lyapunov指数表现出一定的免疫力,该方法有助于提高管道微缺陷识别的灵敏度。同时,利用输入含噪声的实测导波信号与输入实测纯噪声信号后的两个最大Lyapunov指数之比定义损伤指标,当缺陷在一定范围之内时,该指标具有单调递减性,可用于评估缺陷大小。应用本方法,可有效地提高导波检测的灵敏度。
[Abstract]:A sensitive ultrasonic guided wave identification method is proposed by using Lyapunov exponent of Duffin equation. The validity of this method is verified by detecting the guided wave signal in steel tube. Firstly, the different effects of the input Hanning window modulated guided wave signal and pure noise signal on the Lyapunov exponent of the system are compared, and the basic principle of using Lyapunov exponent to identify the weak ultrasonic guided wave signal is given, and the parameters of the detection system are determined. Then, the ultrasonic guided wave is excited and received by piezoelectric sensor in a steel tube 3 m long, and the measured guided wave signal is input into Duffin detection system. The results show that the Lyapunov exponent can effectively identify whether there is a guided wave signal in the echo signal, and the Lyapunov exponent of the noise signal shows a certain immunity. This method is helpful to improve the sensitivity of the pipeline micro-defect identification. At the same time, the damage index is defined by using the ratio of the two largest Lyapunov exponents after the input noise signal and the input pure noise signal. When the defect is within a certain range, the index is monotone decreasing. Can be used to evaluate defect size. By using this method, the sensitivity of guided wave detection can be improved effectively.
【作者单位】：太原科技大学力学系;暨南大学理工学院;
【基金】：国家自然科学基金(11072089,11102125) 山西省自然科学基金(2012021019) 太原科技大学博士启动基金(20102019)
【分类号】：TN911.7

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