2D visualization and optimization of EMAT signal for small defect detection in thick plates

The paper focus on a new combined experimental methodology and signal processing for an EMAT based on a Halbach magnet system in order to increase smaller defect detection in thick metallic plates. The visualization of the EMAT signal using a novel dynamic C-scan procedure is based on a continuous movement of the transducer above plate and an off-line signal processing that is enhanced and optimized for detection of small defects (5%) located on the opposite side of metallic plates (50 mm). The feasibility and performance of the acquisition signal method, and several signal processing algorithms are validated using experimental measurements. The results present an optimized two-dimensional visualization technique for EMAT signal, which can be used for continuous surface scans of plates for detection of smaller defects that self-calibrate as the scan is conducted.