Durability Analysis Of An Aircraft Wing Box

The analysis and experimental study on durability of aircraft structure is an important link which can not be ignored in aircraft design. The test results can be used to validate the aircraft design effectiveness, and the durability analysis technology can guide the experiments, reduce cost, shorten design cycle and, improve design efficiency.The Initial Fatigue Quality (IFQ) of the aircraft structural details is the most important factor that affects the durability of aircraft structure, so the IFQ control is the key link to achieve the durability design. The IFQ of structural details can be explained by Equivalent Initial Flaw Size (EIFS), so in this paper, the durability analysis of the wing box starts with a study on EIFS.In this paper, the rationales and specific measures of durability analysis on aircraft structure are systematicly introduced, and the finite element model is estabilished according to the geometrical model of the wing box. The analysis of this finite element model gives the locations of stress concentration on the wing box, which is also the area with design weakness. Then a durability experiment of the structural details corresponding to those locations is carried out, which gives the metallographic data sets of fractures. Based on the assumptions and principles of probabilistic fracture mechanics, the program to estimate the probability distribution of Equivalent Initial Flaw Size (EIFS) is established, which gives the universal probability distribution of EIFS with the data sets mentioned above. Finally, the quantitative description for the economic life of the aircraft wing box is given.