Design of orthogonal directional shear horizontal electromagnetic acoustic transducer

Abstract

This research proposed an electromagnetic acoustic transducer (EMAT) for generating and receiving orthogonal directional shear horizontal (ODSH) guided waves in the metal plate-like structure. The proposed EMAT generates the fundamental mode of SH wave in the horizontal and vertical direction in the plane of the test sample. The ODSHEMAT combines a new Chevron-like coil design which generates an eddy current effect in the skin depth of the plate surface, and a periodic permanent magnet that applies a static magnetic field vertically with a periodicity equal to its wavelength. The direction of the resultant Lorentz force acting on the test surface-controlled PPM underneath a specific chevron angle of the coil wire. The constructive interference of propagated waves has been developed in the orthogonal directions, enhancing the ultrasonic signals and improving the signal-to-noise ratio. A finite element simulation has been carried out with a thin aluminum plate, keeping the proposed EMAT at the center of the sample. Further, the simulation results show good agreement with the proposed design.