The Crack Growth Analysis And Fatigue Life Prediction Of Aluminum Alloy Plate With Extended Finite Element

The aluminum alloy plates have superior characteristics: light weight, high strength They are widely used in automotive bodies and aircraft wing structures. The components bear load or other external conditions when they are working, and these conditions affect the mechanical properties of the material, especially the components which have cracks can lead to fracture and bring unpredictable disasters. However, cracks can not make components fracture immediately. In order to consider the safety and reliability, 2014-T6 aluminum alloy sheet as research object in this paper. Fracture mechanics theory and extended finite element method as the main ways to analysis the three-dimensional and two-dimensional crack propagation. The fatigue life of the three-dimensional crack bodies make a preliminary prediction.For two-dimensional crack bodies, the straight crack bodies and oblique crack bodies are applied type Ⅰload,type Ⅱ load and typeⅠ-Ⅱ composite load respectively in this paper.The curves of crack length with load and the crack opening displacement with load are obtained. Meanwhile, the static and dynamic stress intensity factor of crack tip are analyzed.The conclusions are: type Ⅰ load have larger effect on the crack propagation.The larger the crack length, the greater the required load. Early required load increment of crack propagation is larger than late. The crack opening displacement increases gradually with increasing load. The crack propagation direction can be controlled by stress intensity factor.For three-dimensional crack bodies, the same crack bodies are applied type Ⅰload, typeⅢ load and typeⅠ-Ⅲ composite load respectively in this paper. The curves of crack propagation length and crack opening displacement are obtained. The dynamic and static stress intensity factors of crack tip are analyzed.The fatigue life are preliminary predicted.The conclusions are: typeⅠcrack propagation length is greater than the other two cracks. The curves of typeⅢ and typeⅠ-Ⅲ composite crack opening displacement occur platforms.Three patterns of stress intensity factor are general increasing trend.K_Ⅰand K_Ⅲwith the trend of crack propagation are the same: increase of stress intensity factor is more gentle while crack growth early but in the final crack growth, stress intensity factor appears soared trends.K_eff-Ⅰ,Ⅲ is substantially linearly increased with the crack growth. The cycles of type Ⅰ crack is 703046.The cycles of type Ⅲ crack is 11488.The cycles of type Ⅰ-Ⅲ composite crack is5259.