High cycle fatigue model based on brittle damage mechanism

The isotropic continuum damage model for high cyclic fatigue derived from irreversible thermodynamic dissipative theory was presented. The model was based on brittle damage mechanism, which is different from Lemaitre model based on ductile mechanism. The model incorporates successfully the high cyclic fatigue into a unified thermodynamic framework. The stiffness reduction was considered as damage variable to simulate the damage process for brittle material and high cyclic fatigue. The effect of stress ratio was considered in damage evolution law. According to the high cyclic fatigue S-N curve under symmetrical loading, the lgS-lgN curve for the arbitrary stress ratio can be derived from the model. The fatigue curve of lgC high strength aluminum alloy were given It shows that predicted fatigue curve is quite consistent with experimental results.