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Electric and magnetic contributions and defect interactions in remote field eddy current techniques.

机译：远场涡流技术中的电磁作用和缺陷相互作用。

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摘要

This thesis investigates the remote field eddy current (RFEC) inspection of stress corrosion cracking (SCC) in steel pipes. The results suggest a conquerable gap between the present experimental level and RFEC detection of SCC on a laboratory scale. The investigation also covers defect source modelling and 3-dimensional finite element analysis (FEA) for detailed studies of defect electric and magnetic interactions, and electric and magnetic individual contributions from defects in steel. It was found that there is a considerable difference between far and nearside SCC signals. The dipole radiation model has been developed to interpret and reconstruct the defect responses from conducting magnetic and steel samples.; Naturally formed SCC fine shallow cracks (15-30% full wall) in a 510 mm steel pipe were measured using an inside-excitor and outside-scan electromagnetic field through-wall transmission setup. Clear crack signals were obtained. The data were compared with inside-scan measurements, combined with finite element results on near and farside crack responses, to find a link to RFEC testing. The crack signal improvement using a pipe wall magnetic saturation technique was also investigated. The results presented in this thesis are part of the work under a contract for investigation of the possibility of detecting fine SCC using RFEC techniques.; The dipole radiation model was proposed and tested. This defect source model describes computable electric and magnetic defect sources, and provides a clear frame to simplify the analysis of complicated defect responses. A classification leading to four basic types of electric and magnetic interactions is proposed and a rule for the interactions is discussed. A general approach using FEA to evaluate electric and magnetic individual contributions from a defect in steel is introduced. The evaluation may provide a quantitative guidance to estimate the gain or loss in a signal when the sample material properties or experimental conditions change. Defect source concepts are discussed and applied throughout the thesis. The thesis also investigates the crack signal dependence of crack volume filling rate, and infinitely-thin-slit behaviour. It revealed the existence of significant residual signal responses, using finite element analysis. These residual signals may have a significant influence on SCC detection. The rich and carefully prepared graphs may prove to be useful for reference in further studies.
机译：本文研究了钢管中应力腐蚀开裂（SCC）的远场涡流（RFEC）检查。结果表明，目前的实验水平与RFEC在实验室规模检测SCC之间存在着可以克服的差距。该调查还涵盖了缺陷源建模和三维有限元分析（FEA），以详细研究缺陷的电磁相互作用，以及钢中缺陷产生的电磁个体影响。发现远侧和近侧SCC信号之间存在相当大的差异。发展了偶极辐射模型，以解释和重建来自导电磁性和钢质样品的缺陷响应。使用内部激励器和外部扫描电磁场穿墙传输装置测量了510毫米钢管中自然形成的SCC细浅裂纹（全壁厚15-30％）。获得清晰的裂纹信号。将该数据与内部扫描测量结果进行比较，并结合近，远处裂纹响应的有限元结果，以找到与RFEC测试的联系。还研究了使用管壁磁饱和技术改善裂纹信号的方法。本文所提出的结果是一项合同的一部分工作，该合同旨在研究使用RFEC技术检测精细SCC的可能性。提出并测试了偶极子辐射模型。该缺陷源模型描述了可计算的电气和磁性缺陷源，并提供了一个清晰的框架来简化对复杂缺陷响应的分析。提出了导致电磁相互作用的四种基本类型的分类，并讨论了相互作用的规则。介绍了一种使用FEA评估钢缺陷中的电磁个体贡献的通用方法。评估可以提供定量指导，以在样品材料属性或实验条件发生变化时估计信号的增益或损耗。本文讨论并应用了缺陷源概念。本文还研究了裂纹体积填充率和无限细缝行为对裂纹信号的依赖性。使用有限元分析揭示了显着的残余信号响应的存在。这些残留信号可能会对SCC检测产生重大影响。丰富且精心准备的图形可能被证明可用于进一步研究。

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  • 作者

    Zhang, Yanjing.;

  • 作者单位

    Queen's University at Kingston (Canada).;

  • 授予单位 Queen's University at Kingston (Canada).;
  • 学科 Engineering Electronics and Electrical.; Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 271 p.
  • 总页数 271
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无线电电子学、电信技术;机械、仪表工业;
  • 关键词

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