On Optimal Adjusting Technology For Reflector Precision Of The Cable-net Deployable Antenna Structures

Considering the requirement for high surface accuracy, low weight of space-borne antenna structures, the initial equilibrium model is investigated systemically and deeply. The static and dynamic analysis, and shape adjustment has been performed. The adjustment process is simulated, and the results show the feasibility of optimal shape adjustment method. The main research works can be described in details as follows:1. Nonlinear finite element model is built, synthesis method for shape finding based on optimization is presented, and the initial equilibrium model is also determined. Two methods for pretensioning the cable net structures are presented: one is that the force of tie cables on cable-net is changed by variation of the force of vertical cables;the other is that the loading distribution will be changed by the variation of up and down cable tensions. The simulation results have shown that the initial model with high accuracy can be obtained by both methods. It can provide the theoretic base for the pretensions of cable-net antenna structures.2. The optimal shape adjustment method is studied. The adjusting strategy and methodology are described through the single radial cable net unit. The optimal mathematic model is built, with the surface accuracy as objective, the strength and frequency as constrains, and solved accordingly. It is found that the efficiency of optimal adjustment method with the variation of cable length as design variables is high. It has based a way for the shape adjustment of whole cable net antenna structure.3. Aiming at the characteristics of large size, weak stiffness, large number of elements and constraints, the number of design variables and constraints is reduced by the technology of variable merger and aggregation function, respectively. The shape adjustment is simulated in two ways: one is that all the sixteen tie cables are adjusted simultaneously, the other is that the adjustment amount and the number of adjustable cables are optimized simultaneously, then shape adjustment is carried out accordingly. The simulation results have shown that the desired surface accuracy can be achieved by two ways, and it can be referred to in engineering shape adjustment.4. Mixed Variables biobjective optimal mathematical model is proposed, with the number of radial units and vertical cables, and the pretensions as design variables, surface accuracy and structural weight as objectives, stresses and frequency as constraints. Biobjective is transformed into single objective by weighted method. The simulation results show that the circular support has a larger effect on the weight of antenna structural. More radial units can be introduced properly in the design stage to improve the surface accuracy. It can provide some reference to the engineering design.5. The present measurement method for the reflector surface precision is summarized, and the method of measuring force on the three dimensional coordinate is presented. The laboring of measuring the force by special tools is also reduced.6. The problem whether or not there are gravity effects on ground and in space is preliminarily studied, the analytic and mathematic model are presented. Mathematic model reasonably approaches the real state by the strategy and method of iteratively comparing the physical reduced scaled model and mathematic model, in order to solve the problem how to guarantee the antenna made on ground can satisfy the requirement in space.