线聚焦超声波法焊接缺陷识别

发布时间：2018-05-02 00:48

本文选题：超声衍射时差法 + 缺陷识别　；参考：《焊接学报》2015年05期

【摘要】：针对常规超声TOFD(time of flight diffraction,衍射时差)法存在超声衍射声场能量低、检测回波信号弱的问题,提出一种线聚焦超声TOFD焊接缺陷识别方法.基于几何声学理论,根据所需主轴声线折射角度及聚焦深度,设计线聚焦超声TOFD法所用的声楔块.通过铝合金板人工缺陷试件的检测,研究线聚焦法的检测灵敏度;通过铝合金板搅拌摩擦焊试件的检测,验证线聚焦法的有效性.结果表明,和常规方法相比较,相同测试条件下线聚焦超声TOFD法的检测灵敏度更高,采集的图像具有更好的对比度,同时能较好地保持图像边缘.所提新方法在改善缺陷分辨力、提高缺陷检出率及降低漏检等方面具有很好的使用价值.
[Abstract]:Aiming at the problem of low energy of ultrasonic diffraction sound field and weak detection of echo signal in conventional ultrasonic TOFD(time of flight diffusion (diffraction time difference) method, a linear focused ultrasonic (TOFD) welding defect identification method is proposed. Based on the geometric acoustics theory and according to the angle and depth of sound line refraction of the main axis, the acoustic wedge used in the linear focused ultrasound (TOFD) method is designed. The sensitivity of the linear focusing method is studied through the detection of the artificial defect specimen of aluminum alloy plate, and the validity of the linear focusing method is verified by the inspection of the friction stir welding specimen of aluminum alloy plate. The results show that, compared with the conventional method, the linear focused ultrasound (TOFD) method has higher detection sensitivity, better contrast and better edge retention under the same test conditions. The new method has good application value in improving the resolution of defects, increasing the detection rate of defects and reducing the missing detection.
【作者单位】：哈尔滨工业大学先进焊接与连接国家重点实验室;
【基金】：国家自然科学基金资助项目(51375002,51005056) 黑龙江省博士后科研启动基金资助项目(LBH-Q13079)
【分类号】：TG441.7

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