蜗卷弹簧缺陷影响超声导波模态变化的辨识

The identification of ultrasonic guided wave modes and their transformation by the surface axial defect in the coil spring

为研究超声导波检测蜗卷弹簧缺陷处对导波模态变化的影响,以预置表面轴向缺陷的蜗卷弹簧为研究对象,首先采用连续小波变换分别计算周向导波三个区域的信号小波系数,通过分析缺陷信号频谱图和小波系数图确定缺陷信号的主要频率成分以及各成分的分布特点,分析不同缺陷情况下小波变换幅度在时频空间的分布情况,再提取1 MHz频率分量上的小波变换幅度包络图,辨识蜗卷弹簧内周向导波传播的主要模态,发现蜗卷弹簧缺陷处的导波模态发生了转换。研究结果表明,利用连续小波变换的幅度包络图可提高导波模态及其转换的辨识能力,辨识由缺陷引起的模态转换,从而检测存在的缺陷。

In order to study the influence of ultrasonic guided wave detection of spiral spring defects on guided wave modal changes,the spiral spring with preset axial defects on the surface was taken as the research object.First,the wavelet coefficients of the signals of three areas of circumferential guided waves using continuous wavelet transform,the main frequency components of the defect signal and the distribution characteristics of each component were determined through analysis of the defect signal spectrum and wavelet coefficient map,the distribution of the wavelet transform amplitude in the time-frequency space under different defects was anylazed.And then we extracted the 1MHz frequency component Amplitude envelope of wavelet transform to identify the main modes of guided wave propagation in the inner circumference of the spiral spring,and it is found that the guided wave modes at the defects of the spiral spring have been transformed.The research results show that the amplitude envelope of continuous wavelet transform can improve the identification ability of guided wave modal and its conversion,identify the modal conversion caused by defects,and detect the existing defects.