Design And Analysis Of Cable-rod Double-Layer Ring Truss Expandable Antenna

Based on the double-layer annular truss,combined with the advantages of small mass and high rigidity,the double-layered circular truss structure is designed.The method of rod replacement is used to achieve high structural rigidity and light weight requirements.Based on the optimization of genetic algorithm,the structural parameters of the new type of cable-rod truss expandable antenna are selected,and the unfolding mechanism is designed according to the unfolding principle of the new type of cable-rod truss.Then,the design and prestressing optimization of the cable net of the new ring truss structure are carried out.Finally,according to the design plan of the organization,the prototype is made and the prototype is subjected to the exhibition and stiffness test to verify the feasibility of the theoretical analysis.The details are as follows:The cable replacement scheme is determined.Firstly,on the basis of maintaining the structural consistency,the original truss is "debared" and frequency analysis is carried out to determine the basic structure of the cable.Secondly,two different types of solutions,full cable and cable-and-cable,are proposed,and each type contains different detailed alternatives.Finally,the vibration analysis of each scheme is carried out by Abaqus software,and the ratio of the fundamental frequency to the mass of each scheme structure and the fundamental frequency of the structure are compared and analyzed to determine the optimal scheme..The structural parameters of the prototype is determined.Firstly,the node coordinates of the truss unit and the length of each member are determined by establishing a mathematical model of the new annular truss,and the total mass of the entire cable-type annular truss is derived.Secondly,the multi-factor and multi-level orthogonal experimental design and response surface analysis method are used to derive the fundamental frequency proxy model related to the optimization parameters.The ratio of the fundamental frequency proxy model to the total mass of the cable-rod annular truss is taken as the objective function.The algorithm optimizes the optimal structural parameters from generation to generation.Finally,the deployment mechanism is designed according to the unfolding principle of the new annular truss..Analysis of cable net configuration and prestress optimization.Firstly,the meshing form of the cable and the number of segments of the cable are determined.Secondly,the coordinates of the cable network nodes are calculated according to the parabolic equation of the cable net.The node coordinate matrix and connection matrix are established according to the rule of node division,and the geometric model of the complete cable network structure is drawn by Matlab programming.Then,the force analysis of the complete cable net structure is carried out to find the balance matrix of the cable net structure.According to the number of free nodes,constrained nodes and boundary cables in the cable network structure,the equilibrium matrix is re-solved,and the new equilibrium matrix is ranked,and the self-stress mode number and displacement mode number of the entire cable net structure are obtained.Then,the stability of the cable net is determined based on the stability criterion.Finally,the genetic algorithm is used to optimize the prestressing of the cable section of the front cable and the partial adjustment cable with the minimum force component of the node as the objective function.Make prototypes and experiments.The prototype was made according to the design scheme of the unfolding mechanism,and the prototype was subjected to the acceptance test and the stiffness test,and compared with the theoretical analysis.