Evaluation of fatigue damage model of CDM by different proportional and non-proportional strain controlled loading paths

Fatigue damage models based on the continuum damage mechanics have been proposed to predict fatigue life of specimens under uniaxial and multiaxial loadings. In this research the fatigue damage model of Chaboche is used to predict the fatigue life under different proportional and non-proportional strain controlled loadings paths. The nonlinear kinematic hardening model of Chaboche is used and it is coupled by nonlinear fatigue damage model. S-N curves of 7075-T6 and 6061-T6 alloys are modeled by applying the fatigue damage model of Chaboche. Constants of the models are determined from S-N curves of two different stress ratios and cyclic uniaxial tests. Ten different loading paths are considered and modeled. Modeling of the multiaxial loading paths is carried out by the obtained constants. Fatigue life is predicted and compared with the experimental results. The experimental and numerical results consist of high and low cycle fatigue tests. Maximum stress in each cyclic strain loops are also obtained by the present models and compared with the experimental results. The present research evaluates the capabilities of the used fatigue damage model.