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: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588637
• 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）：它被称为NDE的红外热成像（或简称TNDE）。基本上，TNDE可以是被动的，也可以是主动的。在主动模式下，外部热刺激被带到样品上，并且对该刺激的响应（用红外相机记录）允许确定被检查部件的表面下结构，例如潜在表面下缺陷（分层等）的存在。在被动模式下，等温线被收集，而不扰动物体的热状态。该提案涉及主动模式。 尽管TNDE越来越受欢迎，但仍然存在挑战，因为许多问题出现在刺激阶段或解释阶段。 拟议的研究计划的目标是面向解决这些问题，他们是在我的研究活动的长期目标的连续性。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，以增强感兴趣的地下工件的响应。 建议包括制定以下内容： ·涡流热成像：利用注入的涡流进行加热，以获得给定缺陷的更多细节。因此，通过两种NDE方案观察到缺陷：热成像和“传统”涡流。 ·冷刺激热成像，针对特定应用使用“冷”而不是“暖”刺激（例如在由于过热而无法进行暖方法的受限区域）。 ·具有适应性加热策略的机器人部署。机器人部署正在成为新的TNDE前沿。 // -解释阶段//：目标包括开发先进的处理方法，以提取所采集数据集的相关特征，计算定量信息（深度、大小、热特性），并实现对数据的可靠解释。信号处理是热图像分析的关键环节。 建议包括制定以下内容： 偏最小二乘回归（PLS）PLS能够分解并随后重建数据集，其优点是省略某些不需要的特征（与非均匀加热/冷却有关）。 ·脉冲相位热成像（PPT）。PPT在频域中探索数据集，但丢失了访问定量信息（缺陷深度）所需的时间信息。计划用小波变换（WT）扩展PPT以规避这一限制。接下来，PLS重建将与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，从而改善NDE诊断。EC是敏感的表面裂纹，但有困难的检测次表面缺陷的热成像是很好的，因为热扩散延伸超出涡流的渗透。 这里介绍的工作是有希望的，因为它将带来新的想法，TNDE社区和工业用户，同时解决关键问题。此外，几个HQP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来。工作的基础具有坚实的理论基础，而拟议方案的结果得到了很好的应用，例如在加拿大的工业中，在以前的研究活动中已经建立了联系，以确保有价值的附带利益。