• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2018, Vol. 54 ›› Issue (22): 15-20.doi: 10.3901/JME.2018.22.015

• 仪器科学与技术 • 上一篇    下一篇

基于自回归谱外推方法的TOFD检测盲区抑制

孙旭1, 金士杰1, 张东辉2, 刘丽丽2, 杨会敏3, 林莉1   

  1. 1. 大连理工大学无损检测研究所 大连 116085;
    2. 中国核工业二三建设有限公司 北京 101300;
    3. 核工业工程研究设计有限公司 北京 101300
  • 收稿日期:2018-02-02 修回日期:2018-07-03 出版日期:2018-11-20 发布日期:2018-11-20
  • 通讯作者: 林莉(通信作者),女,1970年出生,博士,教授,博士研究生导师。主要研究方向为材料无损检测与评价。E-mail:linli@dlut.edu.cn
  • 作者简介:孙旭,男,1993年出生。主要研究方向为超声无损检测信号处理。E-mail:v004sunxu@mail.dlut.edu.cn
  • 基金资助:
    国家重点基础研究发展计划(973计划,2015CB057306)和中央高校基本科研业务费专项资金(DUT17RC(4)02)资助项目。

Suppressionof Dead Zone in TOFD with Autoregressive#br# Spectral Extrapolation

SUN Xu1, JIN Shijie1, ZHANG Donghui2, LIU Lili2, YANG Huimin3, LIN Li1   

  1. 1. NDT & E Laboratory, Dalian University of Technology, Dalian 116085;
    2. China Nuclear Industry 23 Construction Co., Ltd., Beijing 101300;
    3. Nuclear Industry Research and Engineering Co., Ltd., Beijing 101300
  • Received:2018-02-02 Revised:2018-07-03 Online:2018-11-20 Published:2018-11-20

摘要: 结合自回归谱外推方法与超声衍射时差法(Time of flight diffraction,TOFD),抑制直通波脉冲宽度造成的近表面检测盲区。建立碳钢试块模型,并设置上尖端埋深d依次为2.5 mm、3.0 mm、5.0 mm及7.0 mm的底面开口槽,模拟选用中心频率5 MHz、探头中心距34.0 mm的TOFD探头实施检测。利用自回归谱外推方法扩宽傅里叶变换后的混叠信号频带,压缩时域脉冲宽度,分离了混叠的直通波与衍射波,将TOFD检测盲区深度由8.3 mm抑制到2.5 mm以内,实现四个底面开口槽的同时检出与定位。针对碳钢试块中埋深3.0 mm底面开口槽进行试验验证,定位误差为0.30 mm。与常规TOFD和频谱分析方法相比,自回归谱外推方法以高信噪比频带为基础,外推有效频带外的高频与低频范围数据,提高时间分辨率,为TOFD检测盲区内缺陷定位提供了新思路。

关键词: 超声衍射时差法, 盲区, 缺陷定位, 自回归谱外推

Abstract: Combining the autoregressive spectral extrapolation method with the ultrasonic time of flight diffraction method, the near surface detection blind area caused by the pulse width of lateral wave is suppressed. A carbon steel test block model having bottom notches with depth of 2.5 mm, 3 mm, 5 mm and 7 mm is set up. In the simulation, the model is detected using TOFD probes with 5 MHz center frequency and 34.0 mm probe center spacing (PCS). Autoregressive spectral extrapolation method extends the frequency band, compresses time-domain pulse width and separates the overlapping signal. The depth of dead zone is reduced from 8.3 mm to 2.5 mm and four bottom notchesare detected and positioned. Bottom notch having 3.0 mm depth is calculated with the same testing parameters in experiment, and the detected result has an absolute error of 0.30 mm. Compared with conventional TOFD and spectrum analysis methods, autoregressive spectral extrapolation method based on high SNR frequency bands and extrapolate the high frequency and low frequency range data outside the effective band, achieves the goal of improving time resolution and provides a new way for TOFD to detect defects in blind areas.

Key words: autoregressive spectral extrapolation, dead zone, defect positioning, time of flight diffraction

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