Design of bulk wave EMAT using a pulsed electromagnet

Abstract

Typically, permanent magnets used in the electromagnetic acoustic transducers (EMATs), will cause the difficulty of mobility for on-line detection of ferromagnetic materials. In this paper, a pulsed electromagnet EMAT (PE-EMAT) with the effective magnetic field duration of 400 μs is designed. A 2-D finite element model for the bulk wave PE-EMAT is presented including both the electromagnetic field and the acoustic field analysis. The designed PE-EMAT has shown the effectiveness of bulk wave generation and detection compared with the permanent magnet EMAT, which is verified by experiments.

Numerical Study and Optimal Design of the Butterfly Coil EMAT for Signal Amplitude Enhancement

“…The butterfly coil is clamped and fixed to the magnet mold with coil stoppers and finally fixed to the sensor housing. Since the middle part of the butterfly coil has the highest energy [31], it is necessary to focus on the influence of the ratio of the width of the middle magnet D 1 to the width of the middle part of the coil L 1 on the energy conversion efficiency of the EMAT. Consequently, we define ρ as the of D 1 to L 1 , that is:…”

“…However, the effect of EMAT geometrical parameters on eddy currents and Lorentz forces was not addressed in the study. Zhang et al [31] designed a bulk wave PE−EMAT, including a core, a butterfly coil, and a driving circuit for a pulsed solenoid. The experimental results show that the designed new EMAT has better transducer efficiency than the permanent magnet.…”

Development of an electromagnetic bulk wave EMAT

“…Some scholars have verified the feasibility of using electromagnetic EMAT for guided wave and bulk wave detection through simulation and experiments. Zhang et al [1] designed a pulse electromagnet EMAT, demonstrating the feasibility of electromagnet EMAT bulk wave detection. Liu et al [2] proposed a pulse electromagnet EMAT, confirming the feasibility of using this EMAT for guided wave detection.…”