Frequency-Division Multiplexing of Chevron EMAT for Orthogonally Polarized SH Waves

Orthogonally polarized shear-horizontal (SH) guided wave is an essential method to detect crack-like defects in a plate-like metallic structure. Generating dual frequencies with orthogonal polarization of SH waves is more interesting. In this research, a possible multiplexing solution is proposed to simultaneously generate different frequencies of SH waves in the orthogonal direction. A new chevron electromagnetic acoustic transducer (EMAT) design has been proposed to support this idea. The 3-D FEM numerical simulation models with unique and different frequencies have been carried out to generate SH0 mode in mutually normal directions. A comparative analysis has been conducted to distinguish the frequency division and its importance. The simulation results have been validated by experimental data, indicating a discernible correlation between them. This consensus reinforces the potential of the proposed technique as a viable solution for practical nondestructive testing (NDT).