Thermographie et shearographie appliquées au contrôle non-destructif d'interfaces entre de l'adhésif époxy et du CFRP

Le sujet de ce mémoire porte sur l'étude du contrôle non-destructif de structure de béton renforcé par collage de CFRP (carbon fiber reinforced polymer) par shearographie et thermographie active couplées. La méthode d'excitation utilisée conjointement lors de la mise en œuvre de ces deux méthodes est un rayonnement thermique conditionné temporellement par un signal carré. L'observation du champ des températures de surface et des déplacements hors plan de la surface permet la détection et la caractérisation de défauts. Dans un premier temps, des tests de faisabilité ont été conduits pour valider si l'utilisation d’une contrainte thermique de type créneau autorisait des mesures shearographiques (cela ayant été déjà validé dans le cas de la thermographie infrarouge active). Cette série de test s’étant avérée concluante, une étude numérique par modélisation aux éléments finis a été réalisée sous Comsol®. Cette étude numérique a permis de mieux appréhender les résultats obtenus expérimentalement mais aussi de conduire une étude de l’influence de différents paramètres. Des outils d'analyses ont été développés et ont permis de mettre en évidence, entre autre, qu'une évaluation quantitative des défauts était possible

Active Thermal Shearography and Infrared Thermography Applied to NDT of Reinforced Concrete Structure by Glued CFRP

International audienceThis research paper presents the study of thermography and shearography to evaluate CFRP reinforcement of concrete structures. The study explores the strengths and weaknesses of both non-destructive-testing (NDT) methods. It will be shown that by coupling the methods, the detection is more reliable and the defect evaluation more thorough as both the thermal and thermo mechanical properties are tested. Once the core theoretical concept regarding both methods is presented, the viability is demonstrated in the experimentation part of this study. With the experimental results confirming the feasibility of the coupling of both methods, the numerical model conceived allow to better conduct analysis that are not otherwise possible with the experimental results

Comparison between SPT and PT for defect characterization of CFRP plates glued on concrete or wood structures using optical active infrared thermography

International audienceThe objectives of the study summarized hereafter are to compare square pulse and pulsed thermography fordefect detection and characterization of CFRP plates used as structural reinforcement in Civil Engineering applications.Image processing and an inverse method coupled with thermal quadrupoles model are also studied

Square Heating Applied to Shearography and Active Infrared Thermography Measurements Coupling: From Feasibility Test in Laboratory to Numerical Study of Pultruded CFRP Plates Glued on Concrete Specimen

International audienceThis paper investigates thermography and shearography couplings, using feasibility trials and numerical simulations, for non-destructive control evaluations of bonding of carbon fiber-reinforced polymer plates glued over concrete structures. Those are well-known methods in non-destructive testing (NDT) applied to civil engineering, but in this context, they are seen as paired because they use the same excitation source: square-pulsed optical heating. Furthermore, because both methods are based on different properties, the detection of defects is optimised regardless of its nature or type. The combination of the methods allows the measurement of a thermal as well as a thermomechanical response from the structure at the same time. A quick review of those methods and their respective advantage and inconvenient is mentioned. An in-depth study of the interpretation of the thermal and mechanical responses is carried out in relation to the thermal excitation. Then, the thought process behind the conception of the finite element model and its limitation is discussed. The experimental setup, used for feasibility testing, is described as well as a thorough analysis of the experimental and simulated results. Finally, the pairing of both methods is discussed regarding the evaluation of the bond quality, as well as the similitude of the sample and its numerical model

Square pulse heating infrared thermography and shearography applied simultaneously on CFRP tissue bonded to reinforced concrete

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Automatic installation of thermoplastic CFRP monitored by infrared thermography for pipelines

International audienceAutomatic installation of thermoplastic CFRP monitored by infrared thermography for pipeline

Non Destructive Testing by active infrared thermography coupled with shearography under same optical heat excitation

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Dynamic heating control by infrared thermography of prepreg thermoplastic CFRP designed for reinforced concrete strengthening

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Artificial defects in CFRP composite structure for Thermography and Shearography nondestructive inspection

Locating defects in CFRP composite materials is a hot topic in nondestructive inspection (NDI). Beside classical NDI technique, such as ultrasound testing (UT), contactless techniques are actively studied. Generally manufacturers of CFRP structure incorporate artificial defects in the bulk, with different extents and depths, in order to study the performance of a specific NDI technique to detect the defect. One of the most common defects in CFRP is delamination between two layers. This is simulated by inserting teflon sheets which, like air, acts as ultrasound blocker in UT. When such reference part is used to assess NDI performance of thermography or shearography, we only observe respectively the thermal or mechanical response of teflon with respect to external loading used with these techniques. In this work, we assess other possibilities for artificial defects in CFRP matrix. For that a CFRP structure was developed and which incorporates teflon, flat-bottom holes and delamination obtained by the pull-out method. We experimentally studied the signals and we discuss the difference between the various artificial defects methods.TECCOMA (contract N° 7281

Practical simulation of delamination in composites for thermography NDT

This paper tackles the issue of simulating delaminations in reference standards made of CFRP (carbon fiber reinforced polymer) used for non-destructive testing by thermography. Thermography results of a real delamination are compared with flat bottom holes with similar size and depth. Results show a notable difference of the thermal contrast between the real delaminations and the FBH. To replicate the thermal behavior of a real delamination, a solution is proposed by plugging the flat-bottom hole. Thermography tests were conducted with plugs using various materials with thermal properties similar to CFRP