Research on a novel multi-energy coefficient electromagnetic ultrasonic method for cross-scale fatigue damage in metallic materials

Abstract Cross-scale damage detection is crucial for fatigue full-cycle monitoring, and in order to solve the limitations of ultrasonic technology in the degradation of mechanical properties from microstructural defects to macroscopic ones, a highly sensitive electromagnetic ultrasonic cross-scale damage detection technique with multi-energy coefficient is proposed based on Parseval’s theorem. Quantitatively analyzing the relationship between time-domain wave displacement and frequency-domain harmonic energy enhancement in a dual-coil electromagnetic acoustic transducer (D-EMAT), and a mathematical model of fatigue crack cross-scale damage evolution process with multi-energy coefficient α e 1 – η e 2 is established. This proposed model is successfully implemented to determine the different scales of fatigue damage states from microscopic damage evolution to macroscopic crack extension. The experiment shows that the second harmonic energy of the optimized D-EMAT is 3.307 times that of the traditional EMAT. The proposed cross-scale fatigue damage assessment method can achieve a detection error of 2.13%. Multi-energy coefficient electromagnetic ultrasonic detection method provides a new idea for high-sensitivity nondestructive evaluation of cross-scale damage in metallic materials.