Abstract: Damage mechanics method is applied to studying fatigue problems of metallic structure members. Coupling governing equations of stress-damage field and finite elememt-additional loading method are established. Furthermore, formulas of predicting fatigue crack formation and propagation lives of structural members are derived with damage increment as step length. Total lives of typical notched plates with various geometrical parameters, made of 2024 and 7075 are estimated, The results show that the agreements between theoretical S-N curves and experimental ones are very nice. This method requires short CPU time and can be applied to engineering practice.

Key words: damage mechanics, plate specimen with notch, fatigue total life