Fatigue damage accumulation rule of notched specimen

To solve the problem of inaccurate evaluation on fatigue life of notched specimen for the traditional fatigue method, the concept of fatigue damage accumulation is introduced. The stress and strain responses of notched nodes were calculated using finite element method under four different loading conditions. The components of stress and strain along an arbitrary plane for notched nodes were derived based on the transform between old and new systems. Six damage parameters were studied and the variation of them with the plane position was calculated. The maximum value for each damage parameter was then determined. To investigate the rule of damage parameter accumulation, the maximal damage accumulation was calculated for each cycle, and relationship between the cycle number and the damage accumulation parameter was then obtained. It is shown that the fatigue damage accumulation rules of notched specimen for six damage models under four different cycling loads are all linear, and then the fatigue life of notched specimen can be predicted.