Structure Design And Shape Adjustment Of Hoop-Rib Antenna

With the continuous advancement and vigorous development of aerospace technology,the deployable space mesh reflectors present a development trend of large-scale and high-precision.Due to its excellent characteristics such as light weight and large expansion ratio,the hoop-rib antenna is one of the ideal structural forms to realize the large and super large aperture properties of deployable space mesh antenna.Starting from the two aspects of hoop-rib antenna structure design and cable mesh surface adjustment,the problems of deployable truss design,cable net structure design and surface accuracy adjustment are studied respectively in this paper.The specific contents and achievements are as follows:(1)The mechanism and structure design of deployable truss for hoop-rib antenna is studied.Deployable truss is the main supporting and moving part of the antenna structure.The design of deployable mechanism is the primary problem in the antenna structure design.Firstly,according to the geometric parameters of the antenna reflector,the geometric model of the hoop-rib truss is established.Then,the deployment principle of the antenna is analyzed,and the deployable mechanism of hoop-rib truss is designed by using the gear mechanism and the spatial RSSR four-bar mechanism.After that,the three-dimensional models of the deployable mechanism and the hoop-rib truss are constructed.Finally,the kinematics analysis of the deployment process of the antenna truss is carried out by using the Pro/E mechanism analysis module.The analysis results show that the hoop-rib truss can be smoothly and steadily deployed under the driving of designed deployable mechanism and has a better deployment synchronization.(2)The cable net design and structural analysis of the hoop-rib antenna are studied.Firstly,the geometry of the hoop-rib antenna cable net with a double-layer triangle mesh topology is designed and the pretension design is completed.Then,the parametric finite element model of the hoop-rib antenna is established,and the surface accuracy and modal shapes of the antenna are analyzed.Finally,with the constraint of the structural fundamental frequency,the parameter optimization model of the antenna truss structure is established based on the structural optimization design theory,and the hoop-rib antenna structure is taken as an example to validate the model.After optimization,the surface accuracy of the antenna reflector is increased by 59.89%,and the fundamental frequency is increased by 31.58%,and the antenna weight is decreased by 5.27%.The optimization results show that the optimization of structural parameters has a significant improvement on antenna performance.(3)A shape adjustment method of cable net antenna based on LS-SVM is proposed.Firstly,the cable net antenna,a complex system with strong nonlinearity and uncertainty characteristics,is treated as a black box model.Based on the least squares support vector machine(LS-SVM)theory,the LS-SVM prediction model of the antenna structure is established.The mapping relationship between the adjustment amount of the cable and the reflector accuracy is revealed by replacing the physical model with the mathematical model.Then,the mathematical optimization model of the antenna shape adjustment is established.The optimal adjustment amount of the adjustable cable is determined based on the prediction model of the antenna structure.Finally,the cable net of hoop-rib antenna is taken as an example to verify the accuracy of the proposed model and the adjustment method.The results of the example confirm the feasibility and effectiveness of the proposed method.