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Study on Buckling and Fatigue Life of Composite and Aeroengine Composite Case

Author: QiHongYu
Tutor: WenWeiDong
School: Nanjing University of Aeronautics and Astronautics
Course: Aerospace Propulsion Theory and Engineering
Keywords: Composites Casing Flexion Fatigue Fatigue cumulative damage Stiffness degradation Strain ratio S-N curve Life Prediction
CLC: V215
Type: PhD thesis
Year: 2002
Downloads: 598
Quote: 3
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Abstract


Advanced composite materials widely used in aerospace structures, has become one of the four structural materials for aerospace. At present, China is developing a carbon fiber resin matrix composite engine outside ducted casing. The casing of the actual working conditions of the Composite Case buckling characteristics and fatigue life prediction is quite complex, China's new generation of high thrust to weight ratio engine an advance research. Proceed from the practical engineering background research using shell theory and modern numerical analysis techniques, combined with fatigue cumulative damage theory, the problem of buckling and fatigue life of composite aircraft engine and its casing structure carried out a more systematic research. The innovations include: 1 In this paper, considering residual strain stiffness degradation of composite fatigue damage accumulation model. The model is able to describe the dynamic constitutive relation of the material, to overcome the shortcomings of past fatigue damage cumulative damage model the material single attribute - strength or stiffness changes described. When building a model, the proposed approach stiffness and strain ratio and the number of cycles to establish the function relationship and segments with two different functions to describe the damage process. Through gap laminated plates pull - pull fatigue test results of the analysis of the form of an overlay T300/KH-304 composite, establish the of the T300/KH-304 composite fatigue damage accumulation model. The stress was 65% of the ultimate strength of the constant amplitude stress as well as two dual stress fatigue test verification. Nonporous layer plywood fatigue damage accumulation model based on the concept of using the point stress criterion proposed perforated gap composite fatigue damage accumulation model defines stress correction factor. Three different aperture specimen T300/KH-304 composite laminated plates pull - pull fatigue test, the feature points stress correction factor, and the establishment of the perforated plate fatigue damage accumulation model. Aperture of 5mm layer of plywood with the model of the S-N curve for fatigue life prediction and experimental verification. 3, for the first time on a certain type of engine T300/KH-304 Composite Case main overlay to predict the fatigue life of the given operating conditions. Life prediction using the proposed model and the concept of nominal stress method indicate that the main overlay Composite Case better fatigue resistance. 4, for the first time using the finite element method and the cylindrical shell coupling theory analysis T300/BMP-316 Composite Case buckling characteristics alone and coupling of the axial force, torque and internal pressure for further study to lay the foundation; using finite element method analysis of both T300/KH-304 and T300/BMP-316 composite laminated plate buckling characteristics, discussed the impact of the the plies way, size, displacement boundary conditions and other parameters on the buckling characteristics.

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CLC: > Aviation, aerospace > Aviation > Basic theory and experiments > Aircraft strength calculation
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