Innovative Developments of Infrared Thermography for Non Destructive Evaluation

红外热成像无损评估的创新发展

• 批准号: RGPIN-2014-05819
• 负责人: Maldague, Xavier
• 金额: $ 3.06万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=637054
• 关键词: Innovative; Developments; Infrared; Thermography; Non

Infrared Thermography can be applied to the Non Destructive Evaluation (NDE) of materials and structures: it is called Infrared Thermography for NDE (or TNDE for short). Basically TNDE can be either passive or active. In the active mode, an external thermal stimulation is brought to the sample and response to this stimulus, recorded with an infrared camera, allows to determine the subsurface structure of the inspected component such as the presence of potential subsurface defects (delaminations, etc.). In the passive mode, isotherms are collected as is without perturbation of the thermal state of the object. The proposal concerns the active mode.Despite being increasingly popular, TNDE still presents challenges since many problems arise either at the stimulation stage or at the interpretation stage.The objectives of the proposed research program are oriented towards solution of these problems and they are in continuity with the long term goal of my research activities. The present proposed research program offers good potential for novel and significant research activities as follows: // - STIMULATION/OBSERVATION STAGES //: Objectives are to study in depth, through thermal modeling and experiments, the effects of various inspection stimulation schemes in order to enhance response from subsurface artifacts of interest.Proposal includes development of the following: • Eddy current thermography: exploit the eddy current injected for heating to get more details from a given flaw. The flaw is thus observed with two NDE schemes: thermography and «traditional» eddy current.• Cold Stimulation Thermography using a «cold» instead of a «warm» stimulation for particular applications (such as in restricted areas for which a warm approach is not possible due to over-heating).• Robotic deployment with adapted heating strategies. Robotic deployment is becoming the new TNDE frontier. // - INTERPRETATION STAGE //: Objectives consist to pursue the development of advanced processing methodologies to extract the relevant features of the acquired dataset to compute quantitative information (depth, size, thermal properties) and enable reliable interpretation of data. Signal processing is a key procedure in the analysis of thermal images. Proposal includes development of the following: • Partial Least Squares regression (PLS). PLS enables to decompose and subsequently reconstruct a dataset with the benefit to omit certain unwanted features (related to non-uniform heating/cooling). • Pulsed phase thermography (PPT). PPT explores the dataset in the frequency domain but looses the time information needed to access quantitative information (defect depth). Extension of PPT with Wavelet Transform (WT) is planned to circumvent this limitation. Next, PLS reconstruction will be combined with WT PPT. • Data fusion of signals from Eddy Current (EC) and Eddy Current Thermography to calculate the probability of an event (defect detection) thus improving the NDE diagnosis. EC is sensitive to surface cracks but has difficulties to detect subsurface defects for which thermography is good since thermal diffusion extend beyond the penetration of eddy currents. Work presented here is promising since it will bring fresh ideas to the TNDE community and industrial users while solving critical problems. Moreover, several HQPs will be involved at all stages of the proposed research activities. The significance of the proposed activities can be seen on two sides. The basis of the work has a strong theoretical foundation, while results of the proposed program are well applied, for instance in Canadian industries where contacts have already been established during previous research activities, in order to ensure valuable spins-off.

红外热成像技术可以应用于材料和结构的无损评价（NDE），称为无损检测红外热成像技术（简称TNDE）。基本上TNDE可以是被动的也可以是主动的。在主动模式下，对样品进行外部热刺激，并用红外摄像机记录对这种刺激的响应，从而确定被检测部件的地下结构，例如是否存在潜在的地下缺陷（分层等）。在被动模式下，等温线是在不受物体热态扰动的情况下收集的。该建议涉及主动模式。尽管TNDE越来越受欢迎，但由于在增产阶段或解释阶段出现了许多问题，因此TNDE仍然面临挑战。拟议的研究计划的目标是针对这些问题的解决，它们与我的研究活动的长期目标是一致的。目前提出的研究计划为以下新颖和重要的研究活动提供了良好的潜力：// -刺激/观察阶段//：目标是通过热建模和实验深入研究各种检查刺激方案的效果，以提高对感兴趣的地下伪影的响应。建议包括以下发展：•涡流热成像：利用注入的涡流加热，从给定缺陷中获得更多细节。因此，缺陷是用两种无损检测方案观察到的：热成像和“传统”涡流。•冷刺激热成像，使用“冷”而不是“热”刺激，用于特定应用（如在限制区域，由于过热而不可能采用热方法）。•采用适应加热策略的机器人部署。机器人部署正在成为TNDE的新前沿。// -解释阶段：目标包括追求先进处理方法的发展，以提取所获取数据集的相关特征，以计算定量信息（深度、大小、热性能），并实现数据的可靠解释。信号处理是热图像分析的关键环节。建议包括以下发展：•偏最小二乘回归（PLS）。PLS能够分解并随后重建数据集，其好处是省略某些不需要的特征（与不均匀加热/冷却相关）。•脉冲相位热成像（PPT）。PPT在频域探索数据集，但丢失了访问定量信息（缺陷深度）所需的时间信息。扩展PPT与小波变换（WT）计划规避这一限制。接下来，将PLS重建与WT PPT相结合。•涡流（EC）和涡流热成像信号的数据融合，以计算事件（缺陷检测）的概率，从而提高无损检测的诊断。EC对表面裂纹敏感，但由于热扩散超出涡流的穿透范围，因此难以检测热成像良好的亚表面缺陷。这里展示的工作是有希望的，因为它将在解决关键问题的同时为TNDE社区和工业用户带来新的想法。此外，几个HQPs将参与拟议研究活动的所有阶段。拟议活动的重要性可以从两个方面看出。这项工作的基础具有很强的理论基础，而拟议计划的结果得到了很好的应用，例如在加拿大的行业中，在以前的研究活动中已经建立了联系，以确保有价值的衍生。