Aircraft Gun Bay Structure Finite Element Static Analysis And Fatigue Life Estimation

The problem of aircraft structure fatigue is going with the development of aircraft over one hundred years. Except the centralized load impressed from plane other components and airload, the plane gun bay structure is also endured the wallop of the navigate gun launching. The whole structure is in vibrating state all the time. These vibrations will bring dynamic fatigue crack or breakage to the gun bay structure, which causes the failure of rivet and gasoline tank. Estamating the fatigue life-span of gun bay in advance is important to aircraft major overhaul and structure preventive overhaul.The plane gun bay structure is studied in this paper. Components of gun bay structure are recomposed by CATIA toolbox of CAD/CAM, deleting the holes chamfering and reduced weight that have little influence to the result, leading to the universal finite element analyze software ANSYS. Aiming at the guided entity model of apiece component, some frame boards of skin, ventro-board and crossbeam is simulated with curve surface, strengthen rib, frame and bars are simulated with curves in this paper, predigesting entity models to geometry models. The bool operation is used here to incise the common surfaces and curves from components, fuse the superposed points, lines and surfaces, build the geometry models. According to the corresponding geometry models, the body element solid45, shell element shell63,beam element beam188, mass element mass21 are selected to carve up gridding in the ANSYS, building up the rigidity coupling equation of mass element and bole hole, setting up the finite element model of gun bay. The gun bay finite element model built in this paper can be used in the static analysis of gun bay, vibration characteristic analysis, dynamic response analysis and other referenced analysis, providing the theoretic reasons for the static and dynamic modification of gun bay.According to the actual instance of flying, taking off, cruising, diving level, climbing level, launching backlash and lunching rush six load working conditions are designed here, for the gun bay static strength analysis. To the structure static destroy, the weakness part of gun bay is found at the both sides on the top of the air entrance...