• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2018, Vol. 54 ›› Issue (18): 23-32.doi: 10.3901/JME.2018.18.023

• 仪器科学与技术 • 上一篇    下一篇

基于波数分析的激光Lamb波缺陷检测试验研究

刘增华1,2, 冯雪健1,2, 陈洪磊1,2, 何存富1,2, 吴斌1,2   

  1. 1. 北京工业大学机械工程与应用电子技术学院 北京 100124;
    2. 北京工业大学北京市精密测控与仪器工程技术研究中心 北京 100124
  • 收稿日期:2017-06-05 修回日期:2017-12-01 出版日期:2018-09-20 发布日期:2018-09-20
  • 通讯作者: 刘增华(通信作者),男,1973年出生,博士,教授,博士研究生导师。主要研究方向为超声和电磁无损检测技术、结构健康监测、传感器测试技术等。E-mail:liuzenghua@bjut.edu.cn
  • 作者简介:冯雪健,男,1992年出生,硕士研究生。主要研究方向为激光超声无损检测技术。E-mail:fxj@emails.bjut.edu.cn
  • 基金资助:
    国家自然科学基金资助项目(51475012,11272021)。

Experimental Research on Defect Detection of Laser-induced Lamb Waves Based on Wavenumber Analysis

LIU Zenghua1,2, FENG Xuejian1,2, CHEN Honglei1,2, HE Cunfu1,2, WU Bin1,2   

  1. 1. College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing 100124;
    2. Beijing Engineering Research Center of Precision Measurement Technology and Instruments, Beijing University of Technology, Beijing 100124
  • Received:2017-06-05 Revised:2017-12-01 Online:2018-09-20 Published:2018-09-20

摘要: Lamb波的频散和多模态特性,使得利用Lamb波信号的时域或频域特征实现缺陷的定量检测具有一定的困难。基于全光学型激光超声检测系统,采用波数分析方法对铝板中缺陷开展定量检测研究。脉冲激光在固定位置激励,连续激光一维线扫描接收,获得时间-空间波场信号,Lamb波信号的传播特征以及Lamb波与缺陷之间的作用规律被直观的展现。采用二维傅里叶变换将波场信号从时间-空间域转换到频率-波数域,信号中包含的各模态可很好的识别出来。为保留空间信息,借鉴短时傅里叶变换的思想,采用短空间二维傅里叶变换得到沿扫描路径上波数的分布,从中可直观看出缺陷的位置和尺寸。进一步根据波数和频厚积之间的关系,可计算得到缺陷处铝板的厚度。试验结果表明:该方法有效实现了缺陷位置、大小以及深度的评估。

关键词: 波数, 短空二维傅里叶变换, 二维傅里叶变换, 激光Lamb波, 连续小波变换

Abstract: It is difficult to realize the quantitative detection of defects by using the time domain or frequency domain features of Lamb wave signals due to their dispersion and multi-modal characteristics. The study of defect detection quantitatively in aluminum plates is carried out by means of wavenumber analysis based on the full-optical laser ultrasonic testing system. The time-space wavefield signals are obtained by pulse laser in the fixed location excitation and continuous laser one-dimensional scanning acquisition, where the propagation characteristics of Lamb wave signal and the regular pattern of interaction between Lamb wave signal and defect can be visually displayed. The two-dimensional Fourier transform is used to convert the wavefield signal from the time-space domain to the frequency-wavenumber domain where individual modes included in the signals are well discernible. Based on the idea of short-time Fourier transform, for retaining the space information, a short-space two-dimensional Fourier transform is adopted to obtain the distribution of wavenumber along the scanning path, where the location and size of defect can be visually displayed. Furthermore, the thickness of the aluminum plates in the defect area can be calculated based on the relationship between the wavenumber and the frequency-thickness product. Experimental results show that the method can effectively evaluate the location, size and depth of the defects.

Key words: continuous wavelet transform, laser-induced Lamb waves, short-space two-dimensional Fourier transform, two-dimensional Fourier transform, wavenumber

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