Optimization Design Of Bending-twisting Coupled Composite Structure

The bending-twisting coupled adaptive structure has broad application prospects in the structure of fixed-wing aircraft wings and wind turbine blades,and its research on optimization design has important scientific significance.Aiming at the shortcomings of traditional composite bending-twisting coupled structure,such as the high cost and low comprehensive mechanical properties,this paper is foucus on the optimization design of composite bending-twisting coupled structure,and proposes a design scheme of bending-twisting coupled structure based on four types of hygro-thermally stable composite materials.The main research contents are summarized as follows:The comprehensive mechanical properties of single fiber and interlayer hybrid composites and the optimal design method of composite structure are studied.The comprehensive mechanical properties of composite laminates such as stiffness performance,yield strength,buckling load,hygro-thermal effect and robustness are studied.The calculation model of free-layer interlayer hybrid laminates is established,the expressions of stiffness coefficients,thermally internal forces and thermal moments have been derived.The optimization design method of composite structure based on Differential Evolution algorithm is proposed.The influence of key parameters on the efficiency of Differential Evolution algorithm is studied.The bending-twisting coupled structure based on the hygro-thermally stable free-layer extension-shear coupled composites is optimized.The analytical necessary and sufficient conditions for the extension-shear coupled composites which are conducive to the construction of the bending-twisting coupled structure are derived,and the analytical expressions of the twisting deformation for bending-twisting coupled structure are derived.Taking the light fighter wing structure as an example,the Differential Evolution algorithm is used to optimize the design of the bending-twisting coupled wing structure.The numerical simulation method is used to verify and compare the comprehensive mechanical properties of two types of bending-twisting coupled structures.The strength of the two types of bending-twisting coupled structures is predicted using the analytical method.The design scheme of bending-twisting coupled structure based on hygro-thermally stable free-layer extension-twisting coupled composites is proposed.Based on the analytical necessary and sufficient conditions of the hygro-thermally stable extension-twisting coupled composite,the Differential Evolution algorithm is used to optimize the laminates and design the bending-twisting coupled structure.The influence of the deviation of paving angles on the hygro-thermal warping deformation and the extension-twisting coupling effect of laminates is analyzed.The numerical simulation method is used to verify the comprehensive mechanical properties of composite structure.The yield strength is predicted and the correctness of the design is verified using the analytical method.The design scheme of bending-twisting coupled structure based on hygro-thermally stable hybrid free-layer extension-shear coupled composites is proposed.The analytical necessary and sufficient conditions for hygro-thermally stable hybrid extension-shear coupled composites are deduced.The laminates are optimized and the bending-twisting coupled structure is designed to realize the simultaneous optimization of the composite materials and the paving angles.The advantages of interlayer hybrid composites are verified by comparing the optimal solution of stiffness properties for single fiber composites.The influence of the paving angles deviation on hygro-thermal shear deformation of laminates is analyzed using the analytical method.The comprehensive mechanical properties of laminates and the correctness of the design are verified using the numerical simulation method.The design scheme of bending-twisting coupled structure based on hygro-thermally stable hybrid free-layer extension-twisting coupled composites is proposed.The analytical necessary and sufficient conditions for the hygro-thermally stable interlayer hybrid free-layer extension-twisting coupled composites are deduced.The laminates are optimized and the bending-twisting coupled structure is designed.The influences of the paving angles deviation on hygro-thermal warping deformation and extension-twisting coupling effect of laminates are analyzed using the analytical method.The comprehensive mechanical properties of laminates and the correctness of the design are verified using the numerical simulation method.In conclusion,a variety of hygro-thermally stable composite materials are designed to optimize the bending-twisting coupled structure,for the purpose of improving the comprehensive mechanical properties of bending-twisting coupled structure or reducing the cost.The present research is able to provide a technical support for the design of adaptive structures,such as the fixed-wing aircraft wings and wind turbine blades.Furthermore,a more complete optimization design method for the composite bending-twisting coupled structure is formed,which has important engineering application value and scientific significance.