Contribution to the MHD modeling in low speed radial flux AC machines with air-gaps filled with conductive fluids

This work deals with the modeling of the magnetohydrodynamic (MHD) phenomena in the air-gaps of low speed radial flux AC electrical machines filled with incompressible and electrically conductive fluids. The proposed model concerns laminar flows and it is based on a weak MHD coupling at the steady state regimes. The MHD power losses are evaluated and discussed. The model is easy to implement and could be a useful tool for the design and the optimization. An application to marine current turbine is considered

Inverse Problem in Nondestructive Testing Using Arrayed Eddy Current Sensors

A fast crack profile reconstitution model in nondestructive testing is developed using an arrayed eddy current sensor. The inverse problem is based on an iterative solving of the direct problem using genetic algorithms. In the direct problem, assuming a current excitation, the incident field produced by all the coils of the arrayed sensor is obtained by the translation and superposition of the 2D axisymmetric finite element results obtained for one coil; the impedance variation of each coil, due to the crack, is obtained by the reciprocity principle involving the dyadic Green’s function. For the inverse problem, the surface of the crack is subdivided into rectangular cells, and the objective function is expressed only in terms of the depth of each cell. The evaluation of the dyadic Green’s function matrix is made independently of the iterative procedure, making the inversion very fast

ELECTROMAGNETIC CHARACTERIZATION OF ANISOTROPIC AND WEAKLY CONDUCTIVE MATERIALS BY USING RESONANT CIRCUITS

International audienc

SIMPLIFIED MODELING AND MEASUREMENT PROCEDURES FOR ELECTROMAGNETIC LAUNCHERS PERFORMANCES EVALUATION

International audienc

Modélisation des courants induits dans une tôle mince conductrice

International audienc

MODÉLISATION 3D SIMPLIFIÉE POUR L’ÉVALUATION NON DESTRUCTIVE DES MATÉRIAUX COMPOSITES ANISOTROPES

The work presented in this thesis constitutes a contribution to a simplified three-dimensional numericalmodeling of the interaction of an electromagnetic field with laminated carbon fiber reinforced polymer(CFRP) structures, for eddy current nondestructive testing applications.In the limits where the capacitive effects can be neglected, we have developed a model based on an integrodifferentialformulation, in terms of the electric vector potential, for rapid calculations of the sensorsresponses in eddy current testing of laminated CFRPs. This model accounts naturally for the electric currentand magnetic flux conservations, and allows confining the modelling to the active parts of the modelledsystem. These are discretized separately; the multiscale aspects and movements are thus easily treated. Onthe other hand, given the thin layered structures of the CFRPs, and under certain conditions, this model canbe reduced to a quasi-two-dimensional one, involving only the normal component of the electric vectorpotential, thus reducing considerably the size of the resulting algebraic system and the computing time.In a second step, we proposed an approach for the characterization of the conductivity tensor of a CFRPplate, by using a rotating eddy current sensor of a rectangular shape. We have developed analytical relationsdirectly linking the components of the conductivity tensor of the CFRP plate, to the impedance variations ofthe sensor corresponding to its positions parallel and transverse to fibers. The proposed approach has beenvalidated experimentally.Le travail présenté dans cette thèse constitue une contribution à la modélisation numérique tridimensionnellesimplifiée, de l’interaction d’un champ électromagnétique avec une structure en matériau composite stratifiéà fibres de carbone (CFRPs), avec comme principale application l’évaluation non destructive par courants deFoucault.Dans un premier temps, et dans les limites où les effets capacitifs peuvent être négligés, nous avonsdéveloppé un modèle basé sur une formulation intégro-différentielle, en potentiel vecteur électrique, pour descalculs rapides de la réponse d’un capteur à courants de Foucault et des courants induits dans les CFRPs. Cemodèle tient compte naturellement des conservations du courant électrique et du flux magnétique, et permetde limiter le domaine d’étude aux parties actives du système modélisé. Ces dernières sont discrétiséesséparément ; les aspects multi-échelles et les mouvements sont donc traités plus facilement. D’autre part,compte tenu des structures en couches minces des CFRPs, et sous certaines conditions, ce modèle se réduit àun cas quasi-bidimensionnel n’impliquant que la composante normale du potentiel vecteur électrique,réduisant ainsi considérablement la taille du système à résoudre et le temps de calcul.Dans un second temps, nous avons proposé une approche de caractérisation du tenseur de conductivité desCFRPs, en introduisant une structure de capteur à courant de Foucault tournant de forme rectangulaire. Nousavons développé un modèle analytique liant directement les composantes du tenseur de conductivité d’un plien CFRP aux impédances du capteur rectangulaire tournant, correspondant à ses positions parallèle ettransversale aux fibres. Cette approche a été validée expérimentalement

3-D Eddy Current Computation in Carbon-Fiber Reinforced Composites

International audienc

Nondestructive Evaluation of the Conductivity Tensor of a CFRP Plate Using a Rotating Eddy Current Sensor

International audienc

Electromagnetic field modeling in laminated carbon fiber reinforced polymer composites (CFRPs)

International audienc

An Integro-Differential Model for 3-D Eddy Current Computation in Carbon Fiber Reinforced Polymer Composites

International audienc