共查询到18条相似文献,搜索用时 257 毫秒
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主要研究TOFD技术在焊缝检测中的原理以及工艺参数的设定,并采用TOFD、UT、RT按各自的方法标准对人工缺陷试板进行检测,针对其检测结果,结合解剖试验,进行了对比分析,从而得出TOFD检测技术在焊缝检测中的优越性。 相似文献
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声发射检测技术在20世纪70年代得到初步发展,经过多年的发展与完善,已成为现阶段比较成熟的一种无损伤检测方法,并广泛地应用于压力容器检测与压力容器结构完整性的评价方面。首先简要介绍了国内压力容器声发射检测的发展历程,对压力容器声发射检测技术的发展做出相关概述;其次,说明声发射检测技术的应用原理与应用优势;最后,重点阐述压力容器无损检测中声发射技术的应用流程。 相似文献
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阐述了TOFD技术在工程建设中对高温、高压厚壁管道焊接接头检测的各项要求,和对TOFD检测仪器的校准方法,对实际检测中主要工艺参数的设置进行了分析,通过不同的检测方法,对不同类型缺陷性质进行了统计。 相似文献
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C. F. Theresa Cenate B. Sheela Rani R. Ramadevi D. N. Sangeetha B. Venkatraman 《Russian Journal of Nondestructive Testing》2016,52(10):557-568
Ultrasonic Time of Flight Diffraction (TOFD) is now a well established NDE technique finding wide applications in the industry for inspection during manufacture, pre-service and also inservice. While conventionally interpretations of UT images are done by the inspector, a need has always been felt for automated evaluation and interpretation especially when large inspection volumes are involved. Apart from enhancing the speed of inspection, automated evaluation and interpretation provides better reliability of inspection. A number of approaches based on signal analysis coupled with artificial neural networks (ANN) are being tried internationally and limited success has also been obtained. This paper focuses on the development of a semi automatic toolbox for reliable and fast flaw classification in TOFD images using ANN. TOFD images are first acquired and statistical parameters such as mean, standard deviation, energy, skewness and kurtosis are calculated for the region of interest in the images. The classification of the flawed region like Crack, Lack of Fusion, Lack of Penetration, Porosity and Slag Inclusion was materialized using different ANN approaches which made use of these statistical parameters as their input. The process of optimization of a network involves comparison of classification accuracy and the sensitivity of the selected networks. The Cascade Feed Forward Back Propagation (CFBP) network with log sigmoidal activation function proved to be the optimized network model for the data set considered in this study. 相似文献
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Prevention of industrial disasters is a major concern. Nondestructive testing as a reliable tool has played an effective role
in this regard. Ultrasonic testing of heavy press-sure vessels is a common practice. Particularly, a more customary procedure
known as pulse-echo has become a standard in and of itself. In light of the increasing demand for more thorough inspection
of pressure vessels, researchers have begun looking into more innovative means of defect measurement. Fundamentally, the time-of-flight
diffraction (TOFD) flaw-detection procedure is based on the time measured for diffracted waves to travel from the two ends
of a defect, and it is shown to be an effective procedure for size and location determination of a defect [1]. Specifically,
it is demonstrated that this technique is more suitable for thick structures (above 10 mm). Today, the TOFD procedure is used
for operational inspections or quality control of structures during production instead of routine radiography and ultrasonic
NDT procedures [1]. Although TOFD is more often utilized for inspecting welds with simple geometry and small grain steels,
such as face welds with thicknesses from 6 mm to 300 mm, it is useful in inspecting more complex geometries. Such defects
as cracks, lack of penetration, lack of fusion, porosity, and slag in welds and pressure vessels could be diagnosed via this
technique. In this investigation, on the basis of the review of related literature, the principal theory governing TOFD is
discussed. A mathematical model is developed and different aspects have been compared. Advantages and disadvantages of its
utilization are enumerated and specific applications are outlined. Recommendations and suggestions are made for future investigations
and betterment of the procedure.
The text was submitted by the authors in English. 相似文献
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风机叶片在制造、服役和维修阶段的无损检测非常重要。叶片长期在高强度的风力载荷下工作,制造过程产生的任何微小缺陷将在服役中扩大,进一步威胁到风机的正常运行。因而,风机叶片的无损检测一直是工业界与学术界探索的难题。根据叶片视觉检测方法结合无人机技术应用、相关数据包括图像处理方法以及缺陷评判方法的智能程度等方面对前人以及作者所在课题组的前期工作进行综述、总结、分析与对比。目前,可见光视觉检测与红外热成像检测等以视觉为基础的检测手段满足了风机叶片在役运维时非接触、高效、低成本、安全等需求。视觉检测与无人机巡检技术相结合能最大程度的保证人员安全,同时克服了望远镜检测视野受限的难题。然而该检测手段在风机叶片巡检中目前尚存在缺陷定量难、内部缺陷识别率低等方面的不足。通过分析对比可见光检测与热成像检测技术,认为结合智能算法的无人机搭载双光融合检测手段未来有望于解决风机叶片检测中存在的不足。 相似文献
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针对目前复合材料曲面结构缺陷检测技术存在的检测结果不直观、效率低等问题,提出一种基于超声相控阵的缺陷三
维成像方法。 使用三维激光扫描仪获取曲面的点云模型,通过平行截面法规划检测路径,然后使用相控阵轮式探头采集超声图
像数据。 利用均匀三次 B 样条函数拟合检测路径与曲面,根据扫查步长和图像序列关系计算超声图像数据点的空间位置以生
成超声点云集。 最后利用体素化降采样方法对超声检测结果进行重建,实现复合材料内部缺陷的三维成像。 实验结果表明,本
文方法的缺陷成像结果与 CT 检测结果的平均误差为 1. 14 mm,能够快速准确地重建缺陷的位置、形状与尺寸信息,实现复合材
料曲面样件内部缺陷的精确表征。 相似文献