Eddy current testing of ferromagnetic materials: modelling of multiple flows in a planar stratified medium

International audienceFollowing a previous work carried out at the laboratory in the case of one flaw located in a cylindrical ferromagnetic piece, the development presented herein address the case of multiple interacting flaws located inside a planar, stratified and ferromagnetic medium. Simulation results are obtained through the application of the Volume Integral Method (VIM)

Accurate Simulation of EMAT Probes for Ultrasonic NDT Based on Experimental Measurements

During the last years, CEALIST has been developing EMATprobes dedicated to liquid sodium ultrasound applications, including telemetry, defect detection in sodium immersed welds, defect sizing, andmore recently using phased array probes, beam forming images and synthetic focusing. At the same time, simulation tools based on the numerical methods available at CEA LIST have been integrated within the CIVA software platform. This paper focuses on the experimental calibration of the simulation models for liquid sodium EMAT transducers. In particular, it tries to answer the questions regarding choices of input data for the developed models with the goal of carrying out realistic simulations. The full system measurement model, including coil impedances, gains and analog filters need to be taken into account to obtain predictive simulations. Physical measurements allow the precise determination of the needed parameters and allow verifying the different aspects of the EMAT probe behavior. The developed model is then used to propose a design that is optimized with respect to the generation of longitudinal waves in liquid sodium

Modélisation électromagnétique et réalisation d'un dispositif d'imagerie magnéto-optique quantitatif pour la caractérisation des endommagements des structures aéronautiques en alliage léger

CACHAN-ENS (940162301) / SudocSudocFranceF

Modélisation du contrôle non destructif par courants de Foucault de matériaux magnétiques

10 pages; Prix Claude Birac du meilleur posterNational audienceEddy current testing (ECT) is a standard technique in industry for the detection of surface breaking flaws in magnetic materials such as steels. In this context, simulation tools can be used to improve the understanding of experimental signals, optimize the design of sensors or evaluate the performance of ECT procedures. CEA-LIST has developed for many years semi-analytical models embedded into the simulation platform CIVA dedicated to nondestructive testing. The developments presented herein address the case of flaws located inside a planar and magnetic medium. Simulation results are obtained through the application of the Volume Integral Method (VIM). When considering the ECT of a single flaw, a system of two differential equations is derived from Maxwell equations. The numerical resolution of the system is carried out using the classical Galerkin variant of the Method of Moments. Finally, the probe response is calculated by application of the Lorentz reciprocity theorem. The theoretical approach will be presented, as well as comparisons between simulation results and measured data obtained from the literature. The second part of the paper shows first results obtained after a GMR-based probe over a magnetic plate. The advantages of this sensor will be discussed and first results presented

Contrôle non destructif par courants de Foucault : modélisation de plaques ferromagnétiques

Ce travail présente les développements théoriques et numériques fait afin de proposer la modélisation de l'interaction d'une onde électromagnétique avec un ou plusieurs défauts affectant un matériau ferromagnétique stratifié plan en vue d'application en contrôle non destructif. L'approche théorique ainsi que des comparaisons de résultats numériques sont présentées. detection of surface breaking flaws in ferromagnetic materials such as steels. In this context, simulation tools can be used to improve the understanding of experimental signals, optimize the design of sensors or evaluate the performance of ECT procedures. CEA has developed for many years semi-analytical models embedded into the simulation platform CIVA dedicated to non-destructive testing. Following a previous work carried out at the laboratory in the case of one flaw located in a cylindrical ferromagnetic part, the developments presented herein address the case of a flaw located inside a planar, stratified and ferromagnetic medium. The theoretical approach will be presented, as well as comparisons between simulation results and measured data obtained from the literatur