Innovative developments of infrared thermography for non destructive evaluation

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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.