Design Optimization Of Composite Structure For Residual Vibration Suppression

Due to the advantages of high specific strength,high specific modulus and designability,composite materials have been widely used in aerospace,automobile industry,machinery manufacturing and other fields.In some cases,composite structures are affected by residual vibration,excessive residual vibration is harmful to composite structures,so it is necessary to suppress the residual vibration of composite structures.Residual vibration response can be minimized by optimization of composite structures.In this thesis,the residual vibration of the composite structures subjected to initial excitation is suppressed by optimizing the fiber angles,stacking sequence and selection of material for the composite structures.At the end of the thesis,the fiber continuous in the optimized design of composite structures is considered to improve the manufacturability of the optimized design.The main work of this thesis includes:1.The composite structures design model is established based on Discrete Material Optimization(DMO)method.The performance index of a quadratic integral function to measure the residual vibration of the composite structures is used as objective function,and the objective function is simplified by the Lyapunov equation.The optimization model of composite structures with minimum residual vibration is established.The modal reduction method is used to improve the computational efficiency of composite structures optimization,and the adjoint method is used to solve the sensitivity of the objective function with respect to design variables.The Sequential Linear Programming(SLP)algorithm is applied together with a trust region approach in the form of a custom move limit strategy to solve the optimization problem,and the convergence criterion is given.2.Numerical examples are used to illustrate the effectiveness of the minimum residual vibration optimization model for composite structures subjected to initial excitation.Firstly,through numerical examples,the effects of initial excitation,objective function,damping coefficient and boundary conditions on the optimization results are compared.Then,the20-layer laminated plate subjected to initial excitation is optimized to minimize its residual vibration by introducing the Patch design variable.Finally,the element stiffness matrix and element mass matrix of composite structures are extracted by finite element analysis software ABAQUS,the fiber angle and stacking sequence of the composite cylindrical shell structure and the composite wing-like structure is optimized.3.The fiber angle of composite structures is the design variable,the fiber angle of composite structures subjected to initial excitation is optimized to minimize the residual vibration by using the Continuous Fiber Angle Optimization(CFAO)method.The linear constraints of the fiber angle for adjacent elements is introduced into the optimization model to ensure the continuity of the fiber in the optimized design.The results show that the residual vibration of composite structures is obviously reduced by optimized design of composite structures subjected to initial excitation.