ABSTRACT
In this paper, an innovative fatigue model is investigated based on the concept of M-integral in notched elastic-plastic material. The new form of fatigue damage evolution rate (dAD/dN) and fatigue driving force (ΔM) are introduced. The fatigue experimental evaluations of No. 45 steel with a circular notch have been carried out. The change of the total potential energy (CTPE) is introduced to measure the value of M-integral. The results demonstrate that dAD/dN shows an apparent power law relation with ΔM in notched elastic-plastic material. The slope n and intercept λ of lg(dAD/dN)-lg(∆M) curve has linear correlation with the initial notch radius R, but not with applied stress σ. Moreover, the model can clearly describe the two-stage process from the initiation of microcracks to the growth of macrocracks in notched body. It is concluded that the proposed fatigue model can accurately predict the fatigue lifetime of the notched elastic-plastic material.
