Magnetic Non-Destructive Evaluation (NDE) techniques for strain measurement in engineering components

对于涉及大型基础设施的行业，如核电站和石油和天然气输送管道，安全是最受关注的问题。 这一基础设施的故障可能造成严重的环境影响，造成昂贵的财产损失，并导致生命损失。 无损评估（NDE）技术已被开发用于检查工程部件（例如石油和天然气管道，核电厂管道），以确保它们安全有效地运行。 拟议的研究计划侧重于磁性无损检测技术。 由于磁性是应力敏感的，这些技术可以在故障发生之前检测到工程部件中的高应力水平。 拟议的NSERC发现赠款资金将支持正在进行的工作，研究当磁性NDE方法用于检查工程部件时，钢中的应力如何影响信号。 在微观层面上，应力是不均匀的，而是在微晶中分成不同的方向-一些方向承载非常高的应力，而另一些方向承载很小的应力。 这种微观分布的应力称为晶间应力。 克拉珀姆博士早期的工作表明，磁性本身对特定方向的晶粒间应力更敏感，而不是对整体应力模式更敏感。 这项早期工作主要是在简单的实验室样本上进行的，然而，为了与工业NDE直接相关，有必要检查真实的工程部件中的晶间应力并确定它们如何产生磁性特征。 NSERC发现基金资助的拟议研究涉及检查与真实的管道部分中的凹痕和凿痕相关的晶间应力和磁特征。 从这项基础研究中获得的理解将应用于Clapham博士研究小组的其他工业资助工作，以改善磁NDE技术的信号解释，并开发更有效的NDE仪器。 加拿大没有其他团体在这一领域工作，因此参与这项工作的学生获得高度专业化和受欢迎的技能和培训。

Safety is of the utmost concern for industries which involve large scale infrastructure such as nuclear power plants and oil and gas transmission pipelines. Failure of this infrastructure can have serious environmental effects, inflict costly property damage, and result in loss of human life. Non-destructive evaluation (NDE) techniques have been developed to inspect engineering components (e.g. oil and gas pipelines, nuclear power plant tubing) to ensure they operate safely and efficiently. The proposed research program focuses on magnetic NDE techniques. Since magnetism is stress-sensitive, these techniques can detect high stress levels in engineering components before failure occurs. The proposed NSERC Discovery grant funding will support on-going work that examines how stresses in steel affect the signals when magnetic NDE methods are used to examine engineering components. On a microscopic level, stresses are not uniform, but partition themselves into different directions in the microcrystals - some directions carry very high stresses, while others carry little stress. Such microscopically distributed stresses are called intergranular stresses. Dr. Clapham's earlier work has shown that magnetism itself is sensitive more to intergranular stresses in particular directions, rather than to the overall stress pattern. This early work was conducted primarily on simple laboratory samples, however in order to be directly relevant to industrial NDE it is necessary to examine intergranular stresses in real engineering components and determine how they create a magnetic signature. The proposed study for NSERC Discovery Grant funding involves an examination of the intergranular stresses and magnetic signatures associated with dents and gouges in real pipeline sections. The understanding gained from this fundamental study will be applied to other industrially-funded work in Dr. Clapham's research group, to improve signal interpretation from magnetic NDE techniques and also to develop more effective NDE instruments. No other group in Canada works in this field, thus the students involved in this work gain highly specialized and sought after skills and training.