A new chevron electromagnetic acoustic transducer design for generating shear horizontal guided wave.

Guided wave electromagnetic acoustic transducers (EMATs) have a significant role in non-destructive testing and structural health monitoring. It can generate horizontally polarized shear waves propagating axially or circumferentially to characterize the shape and orientation of pipeline defects. This work proposes a new Chevron pattern-like coil structure design with a periodic permanent magnet (PPM) EMAT configuration. This specific design of the EMAT coil can generate a bi-directional shear horizontal wave (SH-wave) and reduce the side lobes. An optimal Chevron angle of coil wires assists in generating orthogonal propagatingwaveforms. These phenomena lead to the constructive interference of propagating waves and develop a resulting wave along the horizontal direction. A 3D FEM modeling and simulation have been carried out and validated with experimental results. The proposed EMAT results are compared with the conventional racetrack PPM EMAT model, which shows a significant improvement over conventional EMATs. A prototype of this proposed EMAT has been developed. It can be used to inspect surface defects in applications such as fuel transportation pipelines.