Buckling And Optimization Of Variable-stiffness Composite Panels Based On Isogeometric Analysis

Compared with the constant stiffness design,composite variable-stiffness panel can adjust the local stiffness distribution by using curvilinear fibers,which is a very promising structural concept.For the load-carrying capacity analysis,the fiber angle cannot be guaranteed to be continuous and smooth in traditional finite element analysis(FEA),due to the mesh discretization,which may cause large prediction error.Meanwhile,with the sharp increase of design variables,it is crucial to develop an efficient optimization methodology for the design of variable-stiffness panels.On the basis of the Mindlin plate theory,the buckling analysis method of composite variable-stiffness panels is proposed based on isogeometric analysis(IGA).Different fiber path functions,boundary conditions and loading conditions are considered to validate the proposed method.From the point-of-view of accuracy,total degree of freedoms and computational cost,the comparison result with traditional FEA indicate that the proposed IGA method has higher accuracy and efficiency.Besides,it should be mentioned that full analytical sensitivity can be derived,which is particularly suitable for the gradient-based optimization of variable-stiffness panels.Then,an integrated framework of exact modeling,isogeometric analysis and optimization for variable-stiffness panels is developed.On this basis,with regard to the characteristics of multiple local optimum,an enhanced gradient-based optimization method with multiple initial designs is established based on design space tailoring method,which can increase the global optimization capacity of complex problems.The comparison result with traditional optimization methods show that the proposed framework improves the optimization capacity in an efficient manner.The proposed method is expected to be utilized in the design of variable-stiffness panels for future aerospace structures.