小波时-频变换的高强钢丝弹性波传播模态分析

发布时间：2018-01-20 04:34

本文关键词： 高强钢丝弹性波纵向导波模态小波时-频变换　出处：《应用声学》2017年06期 　论文类型：期刊论文

【摘要】：超声导波是近年来桥梁拉索无损检测研究的重要方法之一。针对弹性波在高强钢丝介质中传播的多模态频散问题,采用单点时域波形的小波时频变换进行混叠信号的模态识别分离。通过数值求解Pochhammer频率超越方程,计算得到0~1.5 MHz范围内纵向导波模态理论频散曲线;采用有限元模拟半波正弦脉冲激励导波在钢丝中传播过程,由小波时-频变换得到导波模态分布,并进行了不同腐蚀程度钢丝实验对比分析。结果表明,经小波时-频变换得到的第1、2、3阶纵向导波模态与理论值对应吻合,单点时域波形的小波时-频变换结果能够有效识别高强钢丝中的导波模态;钢丝在无腐蚀状态下,一阶纵向导波模态能量占比达57.74%,随腐蚀程度增加,能量更为集中到一阶纵波模态,二阶模态能量逐渐减小。
[Abstract]:Ultrasonic guided wave is one of the most important methods for nondestructive testing of bridge cables in recent years, aiming at the multimodal dispersion of elastic wave propagating in the medium of high strength steel wire. The wavelet time-frequency transform of single point time-domain waveform is used to separate the aliasing signals from each other, and the transcendental equation of Pochhammer frequency is solved numerically. The dispersion curves of longitudinal guided wave modes in the range of 0 ~ 1. 5 MHz are obtained. The finite element method is used to simulate the propagation process of half-wave sinusoidal pulsed guided wave in steel wire. The mode distribution of guided wave is obtained by wavelet time-frequency transform, and the experimental results of different corrosion degree of steel wire are compared and analyzed. The first second order longitudinal guided wave mode obtained by wavelet time-frequency transform coincides with the theoretical value. The wavelet time-frequency transform result of single point time-domain waveform can effectively identify the guided wave mode in high-strength steel wire. Under the condition of no corrosion, the first order longitudinal guided wave mode energy accounts for Prida 57.74. With the increase of corrosion degree, the energy is more concentrated to the first order longitudinal wave mode, and the second order mode energy decreases gradually.
【作者单位】：重庆交通大学土木工程学院;重庆交通大学山区桥梁与隧道工程国家重点实验室培育基地;
【基金】：国家自然科学基金项目(51408090,51478347) 重庆市基础与前沿研究计划项目(cstc2014jcyjA0947,cstc2015jcyjB0014) 重庆交通大学研究生教育创新基金(20160106)
【分类号】：U446
【正文快照】： 1引言超声导波是一种新型的无损检测手段,具有远距离、高效率、受环境干扰小等优点,被广泛应用于管道、板材及复合材料的无损检测[1-3]。相较于传统超声检测使用的体波,导波是由界面间多次反射的纵、横波满足某种边界条件而形成。导波的传播特性往往与传播介质的结构形式、缺

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