航空学报 > 2023, Vol. 44 Issue (4): 426674-426674   doi: 10.7527/S1000-6893.2021.26674

基于半跨模式波的铝合金板底面缺陷TOFD检测

金士杰, 王志诚, 田鑫, 孙旭, 林莉()   

  1. 大连理工大学 无损检测研究所,大连  116085
  • 收稿日期:2021-11-17 修回日期:2021-12-10 接受日期:2021-12-24 出版日期:2022-01-05 发布日期:2022-01-04
  • 通讯作者: 林莉 E-mail:linli@dlut.edu.cn
  • 基金资助:
    国家重点研发项目(2019YFA0709003);国家自然科学基金(51905079);辽宁省“兴辽英才计划”(XLYC1902082)

TOFD detection of bottom defects in aluminum alloy plate by half-skip mode wave

Shijie JIN, Zhicheng WANG, Xin TIAN, Xu SUN, Li LIN()   

  1. NDT & E Laboratory,Dalian University of Technology,Dalian  116085,China
  • Received:2021-11-17 Revised:2021-12-10 Accepted:2021-12-24 Online:2022-01-05 Published:2022-01-04
  • Contact: Li LIN E-mail:linli@dlut.edu.cn
  • Supported by:
    National Key Research and Development Program of China(2019YFA0709003);National Natural Science Foundation of China(51905079);Liaoning “Revitalization Talents Program”(XLYC1902082)

摘要:

采用超声衍射时差法(TOFD)检测铝合金板底面缺陷时,受直通波脉冲宽度影响存在近表面盲区。提出了TOFD半跨模式波法进行盲区抑制,利用一次底面反射波在缺陷端点处衍射波的特征及其在B扫查图像中的对称性推导底面缺陷定深公式。仿真和实验结果表明,对于厚度为7.0 mm的铝合金板,在探头中心距为40 mm、中心频率为10 MHz的检测条件下TOFD半跨模式波法能将近表面盲区抑制64%以上,且深度不小于2.0 mm底面缺陷的定位误差不超过6.32%。与模式转换波及TOFD⁃W波相比,半跨模式波不会与底波混叠且离直通波较近,在铝合金板底面缺陷检测中适用性较强。

关键词: 超声衍射时差法(TOFD), 盲区, 半跨模式波, 铝合金, 定量检测

Abstract:

When Time-of-Flight Diffraction (TOFD) technique is used to detect the bottom defects in the aluminum alloy plate, there is a near-surface dead zone under the effect of the pulse duration of lateral wave. In this paper, a TOFD half-skip mode wave method is proposed to reduce the dead zone. The characteristics of the diffracted wave of the first back-wall reflected wave at the defect tip and its symmetry in B-scan image are employed to derive the depth determination formula of bottom defect. Simulation and experiment results show that with the proposed method, the range of the near-surface dead zone is reduced by more than 64%, and the positioning errors of the defects with depth of no less than 2.0 mm are within 6.32% for the aluminum alloy plate with a thickness of 7.0 mm by using the probes with 10 MHz center frequency and 40 mm probe center spacing. Compared to the mode-converted wave and the TOFD-W wave, the half-skip mode wave is decoupled with the back-wall wave and is close to the lateral wave, presenting stronger applicability in detecting the bottom defect in aluminum alloy plate.

Key words: Time-of-Flight Diffraction (TOFD), dead zone, half-skip mode wave, aluminum alloy, quantitative detection

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