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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567408
• 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.

红外热像仪可以应用于材料和结构的无损检测，简称红外热像仪(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，将外部热刺激引入样品，并通过红外相机记录对该刺激的响应，允许确定被检查部件的亚表面结构，例如是否存在潜在的亚表面缺陷(分层等)。在被动模式中，按原样收集等温线，而不干扰对象的热状态。该提案涉及主动模式。尽管TNDE越来越受欢迎，但它仍然面临挑战，因为许多问题要么出现在刺激阶段，要么出现在口译阶段。拟议研究计划的目标是以解决这些问题为导向，它们与我研究活动的长期目标是一致的。目前提出的研究计划为新的和有意义的研究活动提供了良好的潜力，如下：//-刺激/观察阶段//：目标是通过热模拟和实验深入研究各种检查刺激方案的效果，以增强对感兴趣的地下人工制品的响应。建议包括以下方面的开发：·涡流热像仪：利用为加热而注入的涡流来获取给定缺陷的更多细节。因此，在两种无损检测方案中可以观察到该缺陷：热成像和传统涡流。·针对特定应用(例如，在因过热而不能采用热刺激的受限区域)，使用冷刺激热成像，而不是热刺激。·采用经过调整的供暖策略的机器人部署。机器人部署正在成为TNDE的新前沿。//-解释阶段//：目标是开发先进的处理方法，以提取所获得的数据集的相关特征，以计算定量信息(深度、大小、热性质)，并能够可靠地解释数据。信号处理是热像分析中的一个关键环节。·偏最小二乘回归(偏最小二乘回归)。PLS能够分解并随后重建数据集，从而可以省略某些不需要的特征(与不均匀的加热/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来绕过这一限制。接下来，将把偏最小二乘重构与小波变换PPT相结合。·将涡流(EC)和涡流热像仪的信号进行数据融合，以计算发生事件的概率(缺陷检测)，从而改进无损检测诊断。EC对表面裂纹很敏感，但很难发现亚表面缺陷，这是因为热扩散超出了涡流的穿透范围，所以热成像对此很好。这里提出的工作是有前景的，因为它将为TNDE社区和工业用户带来新的想法，同时解决关键问题。此外，拟议研究活动的所有阶段都将涉及几个总部基地。拟议活动的意义可以从两个方面看出。这项工作的基础有很强的理论基础，而拟议方案的结果也得到了很好的应用，例如在加拿大那些在以前的研究活动中已经建立了联系的行业，以确保有价值的衍生产品。