Modeling and Transduction Analysis of a Novel EMAT Configuration

A coupled finite element model was developed using COMSOL Multiphysics to account for the generation propagation and detection of acoustic wave by the Novel EMAT configuration on CS70 grade of pipe steel. The model can solve the magnetostatic electrodynamic and elastic equations that give rise to acoustic wave generation propagation and detection on the test material. The developed coupled finite element model was validated both analytically and experimentally to establish the validity of the finite element model. The analytical and experimental results obtained were consistent with the numerical result with an average discrepancy less than 9 % percent. Furthermore a novel modelling strategy was developed to decouple and quantify the various transduction forces in operation when normally-biased EMAT and magnetostrictive EMAT configurations are used on various grades of pipe steel materials. The strategy established the value of the critical excitation current beyond which acoustic wave is generated solely by the dynamic Lorentz force mechanism. This work is intended for researchers and professionals in the field of Non Destructive Testing and Structural Health Monitoring.