An Analysis Of Fatigue Crack Growth Simulation And Life Predication In Stiffened Panel

The integrally stiffened panel structure due to greatly reduced the number of rivets and fastening holes, thus significantly reducing the structural weight and manufacturing cost, has become the most promising new type of structural form. But because of the lack of a large number of rivet holes, will make the crack cannot be effectively arrested when the crack is expanded in the structure. In order to ensure the long life of the aircraft damage tolerance design requirement, how to make crack turning behavior and crack arrest phenomenon take place is the key problem in the design of integrally stiffened panel. So the research on the fatigue fracture properties of the integrally stiffened panel has very important theoretical significance to the engineering application.In this paper, the integrally stiffened panel crack path and fatigue life were analyzed using fracture mechanics and finite element method. Firstly, the fatigue crack growth model of the integrally stiffened panel was established, and the reliability of the model was verified by comparing with the crack growth rate test. On the basis of this, the influence of the design mode of stringer on the fracture parameters and fatigue life of the structure was discussed. Secondly, the possibility of crack turning behavior and its influencing factors were analyzed by introducing the theory of crack turning. Finally, the multiple crack damage problem was investigated. The study showed that the effect of different design forms on fatigue crack fracture parameters is not obvious, only when the crack was extended to the vicinity of the stringer. And increasing the thickness of shear strap has the most significant inhibitory effect on crack propagation. Under asymmetrical load and high T-stress environment, the crack can occur turning behavior, and the characteristic process zone size and fracture anisotropy of the material have different influence on crack turning behavior. In the case of multiple cracks, cracks will not turn, but grow straightly and connect to form a large crack. Moreover, the strong interference of adjacent crack tips can lead to the severe increase of stress intensity factor and acceleration of the crack growth rate. Furthermore, the crack propagation life will be seriously shorten. Therefore, effective repairing methods are needed to improve the residual strength and service life of the structure.