Study On Buckling And Fatigue Life Of Composite And Aeroengine Composite Case

The advanced composite materials are used in some primary components in aircraft structures. At present carbon fiber-reinforced composite is developed to use in some aero-engine components in our country. Using the numerical method and fatigue damage theory, the buckling and fatigue on the composite materials and composites case are studied for aero-engine design. The research work in this paper is included following: 1, A fatigue model based on the 'Strain Equivalent Hypothesis' is presented. The fatiguemodel overcomes the deficiency, that is, a material attribute ------stiffness and strength isused to describe the fatigue damage in the tradition fatigue model. In order to express the fatigue damage accurately, the two-stage model for fatigue accumulation damage is presented. The fatigue test of T300/KH-304 laminates is carried out to derive the expression of the model. The fatigue tests of the composite materials under the constant amplitude and two double-level stresses are investigated experimentally. 2, In the definition of the 'Characteristic Dimension' stress and the correct factor fi, a fatigue model is presented for the fatigue of notched laminates. The fatigue test of notched laminates with different diameters is carried out to obtain the factor/ and the fatigue model of notched laminates. The 5 f curve of laminates with a 5mm hole is predicted. At same time, the fatigue test is carried out under different stress level too. 3, Analyzing the stress field of the aero-engine case under the given loads, the fatigue life of the case is predicted through the presented fatigue model and the method of "Nominal Stress". It is found that the main part of composite case will not be fatigue failure. 4, Using the finite element method, the buckling of the case is studied under the loads including the axial force torsion and pressure. The results will be benefit for aero-engine design in the future. The buckling characteristics of the two new kinds of composite (T300/KH-304 and T300/BMP-316) is studied under the same boundary conditions sizes and plies, the anti-buckling ability of T300/KH-304 composite laminate is better than that of T300/BMP-316 composite plates.