Fatigue damage evolution model of stainless-steel-cruciform-joint with weld defect using AE signal

This study involved full-life monitoring of high -cycle fatigue damage evolution in stainless steel cruciform joints with undercuts and their control groups, using acoustic emission technique. Based on continuum damage mechanics, the wavelet packet subband energy of acoustic emission signals was used as the damage variable to investigate the relationship between fatigue damage and acoustic emission signals, to quantitatively assess the extent of fatigue damage. The research findings indicated that the wavelet packet subband energy effectively captured the fatigue damage evolution process in both defective and non-defective specimens. The fatigue damage evolution strips obtained from processing acoustic emission signal data using nonlinear normalization method demonstrated insensitivity to fatigue stress amplitudes. The wavelet packet subband energy exhibited excellent identification ability for early-stage fatigue damage and its development before macroscopic crack formation. This study's outcomes were expected to provide strategies for identification and quantitative assessment of fatigue damage in welded structures throughout their entire service life, as well as predicting remaining life.