Reliability Based Optimization Design Research Of Glass Fiber Composite Radome

With the development of China ’s aviation industry,the number of aircraft has increased year by year.Therefore,to meet the needs of aircraft missions,aircraft lightweight research is the eternal goal of aircraft designers.As an important part of aircraft radar antenna system,the lightweight design of airborne radome is of great significance.With the advantages of high strength,low density,low dielectric constant and low dielectric loss,glass fiber composite material is the preferred material for lightweight design of radome.In this paper,the airborne radome of glass fiber composite aircraft is taken as the research object.Combined with the elastic performance analysis of composite materials,the electrical performance analysis and mechanical performance analysis of the radome,and taking lightweight as the research goal,the radome is optimized based on reliability theory and Kriging model.The research contents of this paper are as follows :In the first part,based on the multi-scale analysis method,the microscopic unit cell and mesoscopic unit cell models are established.The homogenization theory and periodic boundary conditions are used to predict the elastic properties of plain weave composites.The validity of the method is verified by comparing the predicted results with the experimental values.Then the influence of the geometric parameters of the microstructure on the macroscopic equivalent elastic properties of the composites was studied.The results show that the microscopic volume fraction and the mesoscopic yarn width have a significant effect on the elastic properties,and the yarn thickness has little effect on the elastic properties.The performance analysis of composite materials lays a foundation for the subsequent mechanical analysis and reliability optimization of the radome.In the second part,the sandwich type and core layer material are selected,and the calculation method of the electrical performance of the radome is analyzed based on the equivalent transmission line theory.The wave transmission rate at different operating frequencies and incidence angles is calculated by combining the equivalent transmission line theory and electrical performance simulation,and the wave transmission rate at different skin and core layer thicknesses is calculated by simulation.The range of skin and core layer is determined under the requirement of wave transmission rate,which provides reference for the macroscopic layup thickness of subsequent finite element analysis.In the third part,based on the general radome shape design requirements,a finite element model of the composite radome is established,material properties are assigned according to the predicted elastic parameters,constrained boundary conditions are added,and stiffness analysis,modal analysis and stability analysis are performed.The results show that the performance parameters meet the requirements,the mechanical properties are excellent,and the lightweighting effect is good,which indicates that the glass fiber composite material has greater application value in the radome.In the fourth part,considering that the structural geometric parameters are affected by uncertainty factors in actual production,this paper performs reliability-based optimal design of the radome.The microvolume fraction,yarn width,ply thickness and ply angle are selected as the optimized design variables,and the sample set is sampled by using the Latin superlift method.The stiffness,modal and stability analyses of the sample set are performed by composite material performance prediction and finite element simulation,and the corresponding mechanical responses are obtained.And then the reliability optimization mathematical model is established with the goal of radome lightweighting and the set values of stiffness analysis,modal analysis and stability analysis as the constraints.The Kriging model is combined with SORA algorithm to optimize the reliability design of the radome.Finally,the optimal solution is verified by Monte Carlo simulation and finite element simulation,respectively.The results show that the optimized composite radome has good lightweighting effect based on reliability.The research of this paper can provide a reference method for the reliability optimization design of aircraft components under uncertainty factors.