Research On Optimal Design Method Of Variable Rigidity Composite Structure

Variable stiffness composite materials are a new type of composite materials.Compared with traditional composite materials,they have a wider design space and can achieve artificial design of stiffness at various points in the plane.Because fiber bundles of variable stiffness composites are laid along curved paths,the wire laying schemes are complex and diverse,which makes it more difficult to optimize the design.In order to improve the optimization efficiency of the optimization algorithm in the optimization problem of variable stiffness composite materials,this paper selects the appropriate optimization algorithm or improves the current algorithm to improve the optimization efficiency of the algorithm and shorten the total optimization process time.In this paper,MATLAB is used as the optimization design platform,and the related parameters in the Python script are modified to change the finite element modeling parameters,and then imported into ABAQUS to complete the finite element calculation.For optimization problems that do not require finite element calculations,the optimization design is done directly in MATLAB.In this paper,three types of variable stiffness composite materials optimization problems are selected,and their related examples are analyzed:(1)In-plane stiffness optimization design of variable stiffness plates.In this paper,the parameters in the fiber laying scheme are optimized by the differential evolution algorithm so that the stiffness of the board reaches the design target value.At the same time,the current adaptive differential evolution algorithm is improved to improve the optimization design accuracy and the optimization rate.(2)Optimal design of bending deflection of variable stiffness plates.In order to reduce the maximum deflection when the plate is bent under force,a gravitational search algorithm is used to optimize the parameters of the laying plan,and a dynamic dimensional search is introduced to improve the local optimization ability of the traditional gravitational search algorithm.(3)Linear buckling load optimization of variable stiffness cylindrical shells.Based on the linear change of the fiber laying angle,a wire laying scheme with a non-linear variation of the laying angle is designed in this paper.Taking the critical buckling loads of cylindrical shells under various combined loads such as axial pressure,external pressure and internal pressure as design goals,the radial basis function proxy model was used to optimize the relevant parameters in the wire laying scheme,and relevant analysis was performed.The results show that:(1)When dealing with the multivariable(including continuous and discrete)optimization problems in this paper,compared with the existing differential evolution algorithms,the improved adaptive differential evolution algorithm is more stable and computationally more efficient.(2)In the optimization design of the bending deflection of variable stiffness laminated plates,the gravitational search algorithm based on the dynamic dimension search of the neighborhood makes up for the shortcomings of the local search ability of the traditional gravitational search algorithm.The former has higher optimization efficiency and faster convergence rate.The optimization results can provide a reference for the optimal design of variable stiffness laminates.(3)In order to improve the buckling resistance of the variable stiffness cylindrical shell,the radial basis function proxy model was used to optimize the parameters of the two wire laying schemes.It was found that the newly designed wire laying scheme has a wider design space,and the final optimization result is the best.This paper compares two different types of wire laying schemes and finds that their optimized laying angle change curves are very close,which indirectly verifies the accuracy of the optimization algorithm.