CEA List has recently developed numerical tool based on Finite Element (FE) code to simulate the generation of ultrasonic guided waves by EMAT sensors and their scattering by a corroded area in a piping system made of straight and elbow parts.The first part of this study concerns the influence of the corrosion on the propagation of guided waves through an elbow. A set of several (eight) samples of steel corroded elbow with different size of corrosion (extent and depth) has been used for the analysis.The second part focuses on the generation of guided waves by an EMAT probe, by analysis the modal sensitivity of the source. CIVA software has been used to model different EMAT sensors in the context where magnetization and magnetostriction terms are negligible relatively to Lorentz force.Both numerical studies are based on the computation of the scattering matrix characterizing modal conversions by the corroded elbow and excitabilities induced by the source. This modal analysis is useful in order to propose some recommendations for the generation of suitable modes for corrosion detection and size evaluation, in a middle frequency regime. The scattering matrix is obtained with a 3D hybrid method developed at CEA List for several years based on a coupling between Finite Element and Modal Expansion.For the purpose of this study, we extended our Hybrid FE/Modal method to deal with mix modal outgoing conditions using modes of the straight pipe at the entering and modes of the curved pipe at the exit.Moreover, in order to reduce computational costs for the scattering analysis on the corroded elbows, we use the modal formulation based on the combination of two scattering matrix: the corroded part at the input junction of the elbow with the first straight pipe, and the part at the output junction of the elbow with the second straight pipe. The scattering matrices are computed separately and combined using modal propagators.The synthesis of this study involving the generation of guided waves with different EMAT sensors and theirs scattering by corroded elbows will be presented and analyzed.&nbsp;This study has been done in the framework of the project PYRAMID, supported by Agence Nationale de la Recherche (ANR) and Japan Science and Technology agency (JST). The authors wish to thanks all the members of the French-Japanese collaboration.

Efficient Hybrid Fe/modal Simulation of Gw Inspection of Corroded Elbow Pipes With Emat

Paper Proceedings: https://asmedigitalcollection.asme.org/qnde/QNDE2021/volume/85529

ASME 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE2021)

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