| With the progress of space science,spaceborne antennas develop along the direction of light weight,large aperture and high precision to meet the requirements of multi-function,multiband,high gain and high power.Mesh reflector antenna and electrostatically formed membrane reflector antenna can not only meet the requirements of large aperture and lightweight,but also maintain the shape accuracy of the reflector at a high level,so it has been widely concerned.The shape structure,internal force distribution and dynamic analysis of flexible components in the design process of deployable antennas are the main lines of the thesis.The research focuses of the spaceborne deployable antenna are discussed in depth,such as the shape surface analysis method,the dynamic analysis of the deployment process,the driving cable pulley system,cutting pattern analysis and seaming analysis of membrane reflector,et al.The specific work is as follows:1)The method of cable net structure form-finding analysis considering the cable segment connector is proposed.The quaternion is introduced to describe the attitude of the cable segment connector,and the coordinates of the joints of the cable segment are updated by the attitude and size of the cable segment connector,the force balance equation and the torque balance equation in the center of the cable segment connector are deduced,and the shape analysis model of the cable net structure is established.The error of cutting cable length and the change of the shape accuracy are compared when considering and not considering the cable segment connector,and the cable segment length is checked.Considering the flexible deformation of truss,the shape accuracy and the uniformity of pretension distribution,the multi-objective optimization analysis of cable net structure is carried out.Finally,considering the displacement coordination relationship between the truss and the cable membrane structure composed of metal reflective mesh and cable net,the whole cable membrane structure is analyzed and designed.After the discussion of the results,the effectiveness of the method is verified,which is helpful to further improve the design accuracy of the antenna.2)The dynamic analysis method of deployable antennas considering the flexible deformation of truss and the variable topological characteristics of cable net structure is established.A beam element is used to model the flexible truss and a cable element with a transition function is used to model the cable net from slack to tension state,in addition,the quasi-static and dynamic equations of the antenna deployment are established considering the motion constraints in the deployment process.By comparing the results of static analysis and dynamic analysis,the correctness of the model is proved.The method that conjoint dynamic and static analysis is helpful to analyze the mechanics of antenna deployment.3)A cable-pulley element which can describe the transmission of the driving cable between pulley blocks is proposed,and a more complete dynamic model of the antenna deployment is established.An analytical model is first proposed for the driving cable system where the nodal position and the transmission lengths of the cable segment between two adjacent pulleys are selected as the generalized coordinates.This model could simulate the dynamics of the driving cables with time-varying length.Then,the flexible multibody dynamic model of the deployable antenna including the flexible deployable truss and cable net is established.The method is demonstrated by analyzing the deployment of a cylindrical mesh antenna.The simulation results are compared with the corresponding ground prototype experiments.On the one hand,the feasibility of this method is confirmed.On the other hand,the influence factors in the experiment are analyzed,which provides a reference for improving the design accuracy of the antenna.4)The cutting and seaming method of thin membrane reflector is proposed.Based on the membrane theory,the mathematical expressions of the meridional and latitudinal strain on the reflective surface of the thin membrane in the working state are obtained,and the reflective surface in the working state is taken as the starting point of the flattening analysis,so that the complex form finding process is omitted and the analysis efficiency is improved.Secondly,the shape of the planar gore obtained by flattening analysis is taken as reference,and the reflective surface is made,and the simulation analysis and experimental comparison are carried out to verify the effectiveness of the analysis results. |
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