The Variational Principles of Coupled Systems in Fatigue Problem Undergoing Large Range Damage

The coupled systems of fatigue crack initiation problem undergoing large range damage is defined. The zero different work principle, coupled potential energy principle, coupled complementary energy principle in the coupled system is established. By using of coupled potential energy principle, Closed form solution about predicting fatigue crack initiation life of three-dimensional component which leads to large range damage is derived. Compared with reference [1], the close form solution derived from this some. It is proved that the method is correct. The method adopted in this paper is definite in mechanical concept,it can be widely used in analysis of predicting fatigue crack initiation life of various component which leads to large range damage.