Innovative Developments of Infrared Vision for Non Destructive Evaluation

点击翻译按钮获取中文摘要

Various bands of the infrared (IR) spectrum are of interest for the inspection of materials through vision techniques. Our proposal focuses on IR thermography in 1 - thermal bands, 2 - terahertz imaging (far IR). CONTEXT: 1 - // Infrared Thermography // can be applied to the Non Destructive Evaluation (NDE) of materials and structures: it is called IR Thermography NDE (TNDE). Active thermography is when the inspected component is heated (or cooled) as in our proposal. Despite being increasingly popular, TNDE presents challenges with many problems either at the stimulation stage or interpretation stage. 2 - // Terahertz (THz) imaging for material inspection // THz has an high potential for NDE such as to assess presence of various subsurface defects in aeronautical composite components, critical humidity levels in various materials, etc. Material analysis is also possible because different materials have unique characteristics «spectral fingerprints» in the THz region. However THzNDE being new, much work is needed to enhance and interpret signals. OBJECTIVES: Objectives of the proposed research program are oriented towards solution of these problems 1- TNDE: Objectives are to study in depth, through thermal modeling and experiments, a new scheme of inspection: «indoor-drone IR thermography inspection». The principle is to have the inspection proceeds over a large surface by a drone. Indoor flying relaxes flight constraints such pilot license, DOT authorizations and rules, flight duration + collecting data (thank to a ceiling umbilical), presence of inclement weather (rain, etc). Such a scheme is new for TNDE with challenges in terms of flight control, positioning over the object, IR image stitching, convective effects due to propellers, missing portions of thermal time sequences, etc. 2- THzNDE: Objectives are to study in depth THz images which need further processing steps in order get a deep insight of the inner structure of the observed specimens. A time-frequency approach is proposed in conjunction with modeling and experiments. Finally a TNDE and THzNDE data fusion is proposed since both modalities analyze the materials following different schemes. CONCLUSIONS: The research program proposes new key directions in the field of NDE by IR imaging. Work presented here is promising, it brings fresh ideas to the IR-NDE community and industrial users while solving critical problems. Several HQPs will be involved at all stages of the proposed research activities. Significance of the proposed activities can be seen on two sides. The basis of the work has a strong theoretical foundation and results of the proposed program are well applied, for instance in Canadian industries where contacts have already been established during previous research activities, to ensure valuable spins-off. NOTE: Thank to RTI NSERC and CFI grants, our lab. is equipped with TNDE, THz imaging systems and a indoor drone.