Optimization Design And Engineering Analysis Methods Of Composite Wing

Different from traditional materials, composite material has many obvious advantages, such as high ratio of strength to weight, high ratio of stiffness to weight, high thermal expansion coefficient, high temperature resistance, fatigue resistance, impact resistance, and so on, therefore it has been widely applied to the field of aeronautics and astronautics. The designability of composite materials is one of major characteristics, material design and structural design eventually reached a high degree of unity by changing the angle of the layer and stacking sequence, layer area, so composite optimization has practical significance.In the present field of engineering, there are mainly two problems for the optimization design of composite materials, one is the engineering simulation of composite material mainly uses the FEM. Now, the commercial FEM software doesn’t combine the optimization algorithm for composite materials, so the researchers need to write the finite element program and optimization algorithm for a specific problem. Not only increase the optimization cycle, general won’t work. The other one is the composite design exits a huge number of design variables compared to metal structure, each design variable including the discrete variables and continuous variables influences mutually.. In order to improve the efficiency of optimization, it is necessary to choose a suitable optimization algorithm and reduce the number of design variable.From the viewpoint of engineering practice, the exploration of optimization of composite fiber stacking is finished. Firstly research the constitutive equation, failure theory and the finite element theory of laminate and sandwich structure, then find a method of CAD and CAE conversion, by which method established analyzing the digital wing structure; Secondly with the aid of Matlab genetic algorithm toolbox, codes genetic algorithm program and perfect the program according to composite material engineering optimization, improving the efficiency of optimization by combination optimization strategy. Finally construct optimization platform by software Isight, which integrates the Matlab, MSC. Patran/Nastran and on the platform the stability of skin, wing bending stiffness and strength of honeycomb sandwich structure is simulated, completing the optimization of composite material layer information, obtaining satisfied results.Conclusions are obtained:First, with the help of professional commercial software, transforming the digital model to the finite element model can be realized, as a result greatly improving the efficiency of engineering analysis.Second, the optimization strategy which combines the genetic optimization algorithm and gradient optimization algorithm makes up for the deficiency of the traditional genetic algorithm, improving the optimization efficiency.Third, through the establishment of the Isight optimization platform can make composite optimization work general, automatic, parameterized, visual.Fourth, the result is confirmed and the method that introduced is worthy of using in engineering.Fifth, the way of combining shell elements and 3d elements solves the contradiction of calculating stress on the thickness and controlling the number of elements.