Use of Strain-Life Models with Wavelet Bump Extraction (WBE) for Predicting Fatigue Damage

This paper presents the use of strain-life fatigue damage models to observe the cycle sequence effects in the wavelet-based fatigue data editing algorithm.This algorithm is called Wavelet Bump Extraction (WBE), which was developed to produce a shortened signal by extracting fatigue damaging events from the original signal with the retention of the original cycle sequences.Current industrial practice uses the Palmgren-Miner linear damage rule to predict the fatigue life or fatigue damage under variable amplitude (VA) loadings. Using VA loadings, however, this rule does not have load interaction accountability in the analysis.Thus,a more suitable approach has been identified for predicting fatigue damage ofVA loadings, i.e. the Effective Strain Damage (ESD) model. In this study, the cycle sequence effect observation was implemented in both analytical and experimental works using the WBE extracted VA loadings.The study includes the comparison between the experimental and the analytical (using four strain-life fatigue damage models: Coffin-Manson, Morrow, Smith-Watson-Topper and ESD) fatigue damage.The smallest average in the fatigue damage difference was found when using the ESD strain-life model, suggesting the suitability of the this model for analysing VA fatigue loadings.