Comparative Analysis of EMAT Receiving Process between Ferromagnetic and Nonferromagnetic Materials

The two dimensional finite element model of electromagnetic acoustic transducers (EMAT) receiving ultrasonic pulses in ferromagnetic and nonferromagnetic material were established. The model represents several significant improvements over previously published work, as follows:(a) the detail mathematical derivation and solution of key parameters in ferromagnetic and nonferromagnetic materials of test specimens have been described and compared, (b) show different propagation law which excited by EMAT in two type test specimens,(c) in order to improve the intensity of receiving signals of EMAT, orthogonal experimental analysis method is adopted to analyze the influence of different structural parameters of EMAT on receiving voltage for two kinds of tested materials. Finally, according to the characteristics of the two models, the optimal parameters are calculated. After optimization, the voltage amplitude of EMAT receiver is increased significantly. It gets 3.4 times stronger in ferromagnetic material, and 7.3 times stronger in nonferromagnetic material.