Abstract: Two phases, fatigue crack initiation and extension, are rightly associated by damage mechanics method. Based on material parameters in the damage evolution equation computed by means of fatigue curve in the crack initiation process, the relation between crack length and fatigue life in the crack extension process may be obtained by the damage mechanics–finite element method. The above two phases being separately dealt in existing researches are brought into a uniform theoretical frame. By the damage mechanics–finite element method, if one of two sets of test data in crack initiation process and crack extension process is known, another one is acquired. Then, the work of test to obtain fatigue properties are reduced and the handbook of material behavior would be complemented by additional data computed by this method.

Key words: Crack extension, Damage mechanics, Fatigue curve, Finite element method