Developments of electromagnetic acoustic transducers (EMATs) for edge wave generation in non-destructive testing

Ultrasonic guided waves (UGW), particularly edge waves, offer significant potential for non-destructive testing (NDT) due to their ability to propagate over long distances with low attenuation. However, traditional excitation methods using bonded piezoelectric transducers or wedge-based systems face challenges such as the coexistence of multiple wave modes, coupling instability, and vulnerability to variations in surface conditions. Electromagnetic Acoustic Transducers (EMATs) provide a non-contact alternative, enabling robust excitation and detection of ultrasonic waves even under harsh environmental conditions. This study investigates and develops EMATs that are specifically optimised for edge wave generation. The research encompasses theoretical analysis of edge wave propagation, finite element simulations of EMAT-induced edge waves, and experimental validation using custom-fabricated EMATs with optimized coil geometries and magnetic field arrangements. Results demonstrate that EMATs can effectively generate high-purity edge waves with minimal mode interference and low attenuation, thereby affirming their viability as a promising approach for enhancing edge wave-based NDT applications.