Advances in Rayleigh and shear-horizontal EMAT systems for NDT and SHM: A review

This review presents a comprehensive overview of the developments and optimizations of electromagnetic acoustic transducer (EMAT) systems for nondestructive testing (NDT) and structural health monitoring (SHM) in the last two decades. Beginning with an early historical overview, it presents the evolution of EMAT technology through practical applications, advanced signal processing, and hardware innovations. Key design improvements in coil and magnet configurations are discussed in detail, along with the coupling mechanisms responsible for ultrasonic wave generation. The review classifies EMAT systems based on wave modes, including Rayleigh and shear-horizontal (SH) wave modes, and examines representative designs, performance enhancements, and application scenarios. Future directions are outlined, emphasizing hybrid excitation, high-order modes, nonlinear sensing, and intelligent data-driven approaches. This review aims to provide a reference framework for researchers and practitioners seeking to enhance EMAT-based inspection systems for diverse industrial applications.