Layout Optimization Of Stiffeners Based On Topology Optimization Framework

Stiffened panels,with the advantages of high specific strength and specific stiffness,are widely used in aircraft,aerospace,automobile and other industries.Reasonable layout of stiffener can significantly improve mechanical properties of stiffened panels.Topology optimization method,with the advantages of low cost and high efficiency,can significantly improve efficiency of engineering design and shorten engineering design cycle.In this paper,Level Set method and Moving Morphable Components method are used to explore the layout optimization problem of stiffener,respectively.The specific contents are as follows:1.The research on Kirchhoff plate element and equivalent stiffness theory.Traditional size optimization and shape optimization can only change geometric parameters and shape of stiffeners.Meanwhile,solid element is mainly used in topology optimization of stiffened panels,which has low accuracy,and the optimized results often have grey transition zones.In this paper,Kirchhoff plate element is derived.Then calculation efficiency and accuracy of Kirchhoff plate element are analyzed,respectively.Besides,basic idea of equivalent stiffness theory is expounded,and the displacement mode of equivalent stiffness model is compared to that of perfect model.2.The search on layout optimization of stiffened panels based on level set method.In this paper,thin plate and stiffeners are respectively considered as plates with different bending stiffness,with use of equivalent stiffness method.Then the location of stiffeners was described by level set method to perform topology optimization.Meanwhile,The basic flow of layout optimization of stiffened panels based on topology optimization framework is summarized.In this paper,the construction process of velocity field is derived briefly.Several typical cases with various loading and boundary conditions are selected as numerical examples to verified the validity of the proposed method.Besides,the advantages of the method are highlighted by comparison with traditional methods.3.The search on layout optimization of composite stiffened panels based on Moving Morphable Components method.In this paper,a set of components which can move,rotate,dilate,and shrink during the process are used to describe the layout of stiffeners.Then layout optimization of composite stiffened panels can be carried out under MMC based framework.Based on the basic bending theory of laminates,the optimization problem formulation is derived.Then possible discontinuity of the stress/strain tensor on the material interface is analyzed and handled.Several numerical examples verified the flexibility of the proposed method based on MMC framework.Compared with implicit topology optimization,the proposed method can remarkably reduce the amounts of design variables.In addition,an engineering example show the practical significance for guiding engineering application.