Experimental and numerical investigations of shock and shear wave propagation induced by femtosecond laser irradiation in epoxy resins

In this work, original shock experiments are presented. Laser-induced shock and shear wave propagations have been observed in an epoxy resin, in the case of femtosecond laser irradiation. A specific time-resolved shadowgraphy setup has been developed using the photoelasticimetry principle to enhance the shear wave observation. Shear waves have been observed in epoxy resin after laser irradiation. Their propagation has been quantified in comparison with the main shock propagation. A discussion, hinging on numerical results, is finally given to improve understanding of the phenomenon

Eddy Current Modelling for Inspection of Riveted Structures in Aeronautics

International audienceIn the framework of a collaborative project with EADS, a semi-analytical model based on a volume integral method has been developed to simulate eddy current (EC) inspection of riveted structures in aeronautics. The model handles a layered structure by considering a dyadic Green's approach where a fastener and a flaw are introduced as a variation of conductivity in a stack of slabs. Experimental data are used to validate the model

Modular Joining of B-stage Cured Composite Element with Forming Process and Film Adhesive for Structural Application

Composite materials are largely used for structural application in aerospace programmes. One of the main advantages is the function integration with reduction of sub-element numbers. The objective is to propose a new methodology of bonding combining the utilisation of modular joining with forming process. This paper describes optimisation of the curing process to determine an appropriated B-stage cure cycle on injected parts. Mechanical properties and quality assessment of the bonded sample are also presented

A 3D Model for Eddy Current Inspection in Aeronautics: Application to Riveted Structures

International audienceEddy current technique is currently an operational tool used for fastener inspection which is an important issue for the maintenance of aircraft structures. The industry calls for faster, more sensitive and reliable NDT techniques for the detection and characterization of potential flaws nearby rivet. In order to reduce the development time and to optimize the design and the perfor-mances assessment of an inspection procedure, the CEA and EADS have started a collaborative work aiming at extending the modeling features of the CIVA non destructive simulation plat-form in order to handle the configuration of a layered planar structure with a rivet and an embedded flaw nearby. Therefore, an approach based on the Volume Integral Method using the Green dyadic formalism which greatly increases computation efficiency has been developed. The first step, mod-eling the rivet without flaw as a hole in a multi-stratified structure, has been reached and validated in several configurations with experimental data

Modélisation d'un procédé de contrôle non destructif par courants de Foucault de structures rivetées en aéronautique

International audienceOne of the Eddy Current (EC) testing issues in aeronautics is the inspection of fastened structures to detect flaws nearby rivets which can grow because of mechanical stress. EADS and the CEA LIST have started a collaborative work with the support of the Île-de-France Region to develop a simulation tool of EC fastened structures testing, integrated to the CIVA platform, aimed at conceiving testing methods, optimizing and qualifying it. The volume integral method using a multilayer Green dyadic formalism has been chosen in order to get a fast resolution of Maxwell equations. The flaw response simulation mostly has to cope with a scale issue between the size of the rivet and the one of the flaw. The whole model has been experimentally validated and compared to other simulation models at the important development steps.Un des enjeux du CND par Courants de Foucault (CF) dans le domaine aéronautique est l'inspection de structures rivetées pour détecter d'éventuels défauts qui peuvent se créer en pied de rivet. Pour répondre à cette problématique, EADS et le CEA LIST ont collaboré avec le soutien de la Région Île-de-France afin de développer un modèle de simulation au sein de la plate-forme logicielle CIVA, adapté à ce type de configuration, pour la mise au point de méthodes de contrôle, leurs optimisations et leurs qualifications. L'approche théorique choisie est le formalisme d'équations intégrales de volume mettant en jeu des dyades de Green multi-couches et leur mise en oeuvre numérique, ce qui permet une grande rapidité de résolution. La prise en compte par le modèle d'un défaut en pied de rivet met en jeu la présence de deux objets de tailles très différentes dans une même configuration. Le modèle a ensuite fait l'objet de validations expérimentales et de comparaisons avec d'autres modèles de simulation aux différentes étapes clefs de son élaboration