Study on the accumulative fatigue damage rules under multiaxial two-stage step spectra constructed by loadings with similar lives

摘要

In this paper, the influence on the multiaxial fatigue damage accumulation caused by loading path variation was studied. For 2024-T4 aluminium alloy, the damage evolution during the entire life was first observed. On the basis of the observation, the stage Ⅰ of fatigue damage evolution was further divided into two sub-stages, and the dominant stress parameters of these two sub-stages were proposed. Taking the dominant stress parameters into account, a phased accumulative fatigue damage model was proposed. Then, 12 multiaxial two-stage step spectra constructed by loadings with approximately identical fatigue lives were carried out on 2024-T4 aluminium alloy. The accumulative fatigue damage was calculated by the proposed model, and another five commonly used models and the calculated results were compared. According to the comparison, the newly proposed model had the most accurate results with the smallest scatter.