NUMERICAL SIMULATIONS OF AN ELECTROMAGNETIC ACOUSTIC TRANSDUCER RECEIVER SYSTEM FOR NDT APPLICATIONS

Development of a novel multistage numerical model of an electromagnetic acoustic transducer (EMAT), with particular emphasis on an EMAT receiver is presented. This model includes five separate modeling states, i.e. 1) static magnetic field simulation of an electromagnet, 2) pulsed eddy current distribution of a generic meander-line coil suspended over a conducting specimen, 3) Lorentz force distribution due to the interaction of the static magnetic field with the eddy current distributions, 4) acoustic wave generation and propagation based on the dynamic Lorentz forces, and 5) acoustic wave detection by an EMAT receiver. In particular, this paper describes how the transient particle displacement fields are converted into an induced voltage response as part of the EMAT receiver system. Numerical simulations show that the voltage response is dependent on the wire spacing of the receiver coil.