Abstract: Damage mechanics method is applied to study fatigueproblems of metallic structure members. Using the micro-structuralmechanical model, the anisotropic damage coupled constitutive relations andfinite element-additional loading method are established.Fatigue crack formation and propagation lives of structural members arepredicted with the damage increment as the step length. Total lives of typicalnotched bars made of 30CrMnSiNi2A are estimated. The results showthat the agreements between theoretical S-N curves and experimentalones are very good. This method requires not much of CPU time and can beapplied to engineering practice in estimating lives and designingagainst fatigue.