| 摘要: |
| 针对常规超声TOFD法存在近表面检测盲区的问题,提出一种纵波三次反射的TOFDW检测模式.分析了TOFDW模式的声传播特性,并阐明了该模式的检测原理.通过人工缺陷检测,研究了该模式检测信号和图像特征及检测灵敏度和精度.对实际焊缝进行了检测,并通过破坏性试验对无损检测结果进行了验证.结果表明,TOFDW模式能够识别常规模式下无法辨别的近表面缺陷,可有效检测到埋藏深度1.0 mm的人工缺陷;同时,该模式具有较高的量化测量精度,近表面人工缺陷埋藏深度测量的平均绝对误差不超过0.3 mm. |
| 关键词: 超声衍射时差法 近表面盲区 缺陷检测 |
| DOI： |
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| 基金项目:国际合作项目(2007DFR70070);国家自然科学基金项目(51005056);中国博士后科学基金项目(20080440873) |
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| Mode for near surface defect detection based on ultrasonic TOFD |
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CHI Dazhao1,2, GANG Tie1, YAO Yingxue2, YUAN Yuan1, SHENG Chaoyang1
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1.State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, China;2.School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
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| Abstract: |
| Aims at the problem of near surface dead zone in ultrasonic TOFD(time of flight diffraction) method,a modified testing mode named as TOFDW,which employs the three-fold reflected longitudinal wave from the bottom of the piece under testing,is presented based on the conventional TOFD technique.The characteristic of sound propagation in TOFDW mode is analyzed and its detection principle is illustrated.Through artificial defect testing,the features of tested signal and image are cognized,and the testing sensitivity and accuracy of the testing mode are studied.Weld piece is tested and the result is verified by destructive testing.The experimental results show that TOFDW model can identify the near surface defect that cannot be distinguished by using conventional methods,and the artificial defect with buried depth of 1.0 mm can be effectively detected.The model has a high quantitative accuracy,and the average absolute error of artificial defects location is less than 0.3 mm. |
| Key words: ultrasonic TOFD near surface dead zone defect detection |
