Electromagnetic Stimulation of the Acoustic Emission for Fatigue Crack Detection of the Sheet Metal

A new electromagnetically induced acoustic emission technique (EMAE) is presented in this paper. Due to the acoustic emission signal generated by the electromagnetically induced high-density eddy current pulse, EMAE can locate small flaws or cracks in thin-walled structures nondestructively in order to inspect specific areas without loading the whole structure. The acoustic emission (AE) signal captured by conventional or fiber optic AE sensors is modulated at the defect due to the crack closure. The differences can be found by comparing modulated AE signals from the defects and ones from the intact region in the spectrum. In this paper, the finite element model of EMAE has been implemented based on the concrete experiment models. The sample's deformation has been analysed when the exciting coil locates at different position. The results of experiments indicate that electromagnetic transient modulation of the acoustic emission could be used to enhance detection of small cracks in thin-walled metallic structures.