Study On The Contoured Beam Design Of Space-Borne Cable Mesh Reflector Antennas

For large space-borne mesh developable antennas,there are many ke y technical problems from the scheme design,theoretical analysis to the stages of manufacturing and experiment adjustment.Several key technical problems,as the form-finding design,shape adjustment,contoured beam synthesis and on-orbit coupling dynamics analysis,are dealt with.The main works can be described as follows: 1.A uniform-tension form-finding design method is proposed.First,the mechanical model of hoop truss cable mesh antennas is derived,based on which the two-step and one-step uniform-tension form-finding methods are proposed.Through uniform-tension design,the tensions of the front and rear cable nets will be completely uniform,respectively.Second,considering that the number of the truss supporting nodes must be reduced in practical engineering,an optimization method is established to design the tensions of the boundary cables,through which the tensions of the internal cables are ensured to be uniform with the effective aperture of the reflector not being reduced.Then,as the de formation of the supporting truss can affect the shape and tension of the cable nets,a uniform-tension form-finding method of cable-beam structures is proposed based on iteration strategy.The proposed method is effective for the typical mesh antennas with back-to-back cable nets.2.A shape pre-adjustment method considering the thermal loads in space is presented.First,the incremental equilibrium equation,the incremental displacement equation,the incremental tension equation and the incremental reflector accuracy equation are derived.Based on the incremental equations,a shape adjustment optimization model under a single temperature condition is established.Then,with the extremum of the objective function being discussed,the other shape adjustment optimization model is established considering the whole temperature interval.Through the shape pre-adjustment under the temperature interval,the whole variation range of the antenna's on-orbit shape error is greatly reduced.3.A novel contoured beam synthesis based on integrated electromagnetic-structural design is proposed.First,with the combination of the physical optics method and the force density method,the integrated electromagnetic-structural analysis model is constructed.Based on the analysis model,an optimization model is established for the contoured beam synthesis of cable mesh antennas.In the model,the force densities of the cables are chosen as the design variables,and the equilibrium equations of the cable net structure are taken as the constrains,and both the far-field electromagnetic performance and the tension uniformity of the cable net structure are considered as the objective functions simultaneously.Through the method,the contoured beam synthesis of the cable mesh antenna can be realized with the cable net structure being tensioned in the equilibrium state.4.An innovative structure design approach is proposed for the contoured beam synthesis of cable mesh antennas.In order to realize the force balance of the concave-convex shaped mesh reflector,a three-layer cable net structure approach is proposed.With an auxiliary layer of cable net structure added to the AstroMesh structure,the mesh reflector will be balanced to form the desired concave-convex shaped surface.On one hand,an optimization model is established to design the shaped reflector to meet the requirements of the far-field pattern.O n the other hand,the pretension of the three-layer cable net structure is designed to demonstrate the realizability of the approach in practical engineering.Simulation results show that the propose approach can not only provide a satisfactory contoured beam but also has a good tension uniformity,which is realizable in practical engineering.5.A coupling dynamics analysis method is presented for the on-orbit satellite-antenna systems.First,the angular momentum equation of the satellite system and the energy equation of the flexible structure are derived,based on which the satellite-antenna coupling dynamic analysis model is established.Second,according to the geometric relationship between the on-orbit antenna structure and the Earth shadow,the finite element method is adopted to analyze the time-varying temperature field of the on-orbit antenna structure.Then,with the time-varying temperature field being equivalently taken as time-varying nodal loads and applied on the antenna structure,the thermally induced coupling dynamic response of the satellite-antenna system are analyzed.Simulation results show that significant vibration response will be induced by the thermal loads if the thermal response time is close to the structure response time.