Innovative developments of infrared thermography for non destructive evaluation

在材料的热无损评价（TNDE）中，将外部热刺激引入待检测部件，并对该刺激进行响应，用红外摄像机记录，从而确定该部件的地下结构，揭示潜在的地下缺陷，如空洞、分层、孔隙等。TNDE在增产阶段或信号记录和解释阶段都会出现许多问题。拟议研究计划的目标是解决这些问题，并与我们研究活动的长期目标保持一致。*刺激/记录阶段：目标是通过热建模和实验深入研究各种检测刺激程序（光学加热、感应涡流加热、超声波加热）的效果，同时通过修改组件中发射的热波的光谱含量来开发自适应加热，以最大限度地提高缺陷的可见性。*解释阶段：目标包括追求脉冲相位热成像（PPT）的发展，其中频率分析能够计算受噪声影响较小的相位图像，并允许更深的探测。对PPT的一种改进是使用小波变换保持对提取感兴趣的地下伪影的定量信息所需的时间信息的访问。*自动/辅助诊断：为提高可靠性，便于工业实施，提出涡流数据与热感加热融合，并结合红外图像处理中的“偏度”进行自动检测。研究生将积极参与这里所介绍的工作，这是有希望的，因为它将为TNDE社区和工业用户带来新的想法。拟议的活动具有双重意义。工作基础具有较强的理论基础，而所提出的方案的结果很好地应用于工业实例，以确保有价值的转移。

In Thermal Non Destructive Evaluation (TNDE) of materials, an external thermal stimulation is brought to the component to be inspected and response to this stimulus, recorded with an infrared camera, allows to determine the subsurface structure of this component revealing the presence of potential subsurface defects such as voids, delaminations, porosities. Many problems arise in TNDE either at the stimulation stage or at the signal recording and interpretation stage. Objectives of the proposed research program are oriented towards solution of these problems and they are in continuity with long term goals of our research activities. The present proposed research program offers good potential for novel and significant research activities: * Stimulation/recording stages: The objectives are to study in depth, through thermal modeling and experiments the effects of various inspection stimulation procedures (optical heating, inductive - eddy current - heating, ultrasonic heating) while developing adaptive heating by modifying the spectral content of the launched thermal waves in the component to maximize defect visibility. * Interpretation stage: The objectives consist to pursue development of the pulsed phase thermography (PPT), in which a frequency analysis enables to compute phase images less affected by noise and allowing deeper probing. A proposed enhancement to PPT is the use of the Wavelet transform maintaining access to the time information necessary to extract quantitative information of subsurface artifacts of interest. * Automatic/aided diagnosis: to improve reliability and to facilitate industrial implementation, fusion of eddy current data and thermoinductive heating and the use of "skewness" in infrared image processing combined to automatic detection are proposed. Graduate students will be strongly involved in the work presented here which is promising since it will bring fresh ideas to the TNDE community and industrial users. The significance of the proposed activities is two-fold. The basis of the work has a strong theoretical foundation, while results of the proposed program are well applied for instance in industries in order to ensure valuable transfer.