基于半跨模式波的铝合金板底面缺陷TOFD检测  

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

作　　者：金士杰[1] 王志诚 田鑫[1] 孙旭[1] 林莉[1] JIN Shijie;WANG Zhicheng;TIAN Xin;SUN Xu;LIN Li(NDT&E Laboratory,Dalian University of Technology,Dalian 116085,China)

机构地区：[1]大连理工大学无损检测研究所,大连116085

出　　处：《航空学报》2023年第4期226-234,共9页Acta Aeronautica et Astronautica Sinica

基　　金：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)。

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。When Time-of-Flight Diffraction(TOFD)technique is used to detect the bottom defects in the aluminum al⁃loy 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,pre⁃senting stronger applicability in detecting the bottom defect in aluminum alloy plate.

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 

分 类 号：V252.2[一般工业技术—材料科学与工程] TH142[航空宇航科学与技术—航空宇航制造工程]