| Composite wing design, in which involved are many disciplines such as structural mechanics, aerodynamics and control engineering, is a complicated process. For these disciplines there are different requirements and complex couplings. Integration and trade off using efficient numerical analysis methods and advanced optimization algorithms are needed to obtain a high quality design. Two important aspects of the integrated optimization of composite wing structures are focused in this thesis: design-oriented structural analysis methods and integrated optimization algorithms.First, the repeated structural analyses for static and dynamic characteristics are needed in the integrated optimization of composite wing structures. In this situation, the Finite Element Model (FEM) is time-consuming, while the continuum Equivalent Plate Model (EPM) is more efficient and often used.At present, the equivalent plate methodology based on global Ritz solution technique has been used in the studies of aeroelasticity and aeroelastic optimization of composite wing structures, but it stiff exits space to develop. A new equivalent platemodeling technique for composite wing structures is developed in the present work.The new technique allows First Order Shear Deformation Plate Theory (FSDPT) orClassical Plate Theory (CPT) to be used for modeling built-up wing structures, sandwich wing structures or the wing structures which the volume between upper and lower skin is empty or solid with a'general planform. The Rayleigh-Ritz method is used to lead to analytical expressions for the stiffness and mass matrices and load vector as well as their sensitivities, which uses the simple polynomials to define assumed displacement functions, geometry and construction of wing structures. Excluding some selected terms from the displacement functions or using stiff springs at the specified locations imposes boundary conditions. The accuracy of calculated results is improved by including transverse shear effects and using multiple sets ofRitz functions in the analysis. Equivalent skin and sandwich techniques are presentedfor enhancing efficiency.Secondly, because of the flexibility and complication of the integrated optimization of composite wing structures, there are many difficulties in the design optimization when using the mathematical programming technique. To overcome these difficulties, in this paper(1)A Hierarchical Design Optimization (HDO) technique is developed. HDO divides the integrated optimization of composite wing structures into two sub-problems that are easy to be solved: upper level optimization and lower level optimization. In upper level optimization, the thickness and geometry factors of composite skins and webs as well as other structural dimensions are taken as design variables. Then, considering the behavior constraints and the side constraints, the structural mass is minimized by the mathematical programming technique. In lower level optimization, the mathematical programming technique or the Genetic Algorithm (GA) is used to search the practical stacking sequence of composite skins and webs to realize the given thickness and geometry factors from upper level optimization.(2) A Stacking Sequence Optimization (SSO) method of composite laminates based on GA is suggested in lower level optimization of HDO. In SSO, the thickness of each stack of the laminate must be integer times as thick as that of single ply, the angle of each stack of the laminate is selected from a set of standard angles, and the stacking sequence can change arbitrarily. When material and ply angles of the laminate are selected, GA is used to giye the optimal laminate that meets the given requirements of thickness and geometry factors.(3) An adaptive crossover operator, an adaptive mutation operator and a multiple and variable elitist operator are proposed to enhance the reliability andefficiency of GA. The adaptive crossover and mutation operators can automatically change the probabilities of crossover and mutation accord...
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