Dynamic Analysis And Optimal Design Of Double-ring Truss Deplovable Antenna

Demand for large-caliber and ultra-large-caliber antennas is increasing with the rapid development of the space science and astronautical technology. However, the caliber of antennas is severely restricted by weight and volume limitations of the launch vehicle such as the cowling for space use. Ultimately, this creates a design space governed by competing properties, where the antenna is desired to be as light and as small as possible during transportation, while as large as needed for effective operation when the antenna is fully deployed on the orbit. Foldable and deployable supporting structures have proven to be an effective system for addressing this challenging design problem. This paper emphasized on the design and dynamic analysis of the double-ring deployable truss antenna, and researched on the frequencies, modal analysis and structural optimization subjected to dynamic constraints.On the basis of lots of domestic and foreign literatures, the current research situation of large-caliber and ultra-large-caliber antennas. Three basic different types of deployable antennas are introduced and it illustrates the necessity of the design and research of new kind of deployable truss antennas for space use. The design and manufacture of the scaled model and the tested results verified the numerical results. Therefore, the necessity and significance of the research of the double-ring deployable truss antenna are proved.This paper starts with the general single-ring deployable truss antenna, and introduced the merits of the single-ring deployable truss antenna which is widely used nowadays. But the stiffness of the single-ring deployable truss antenna decreases sharply with the increasing caliber of the antennas when the space technology develops fast and fast. So the single-ring deployable truss antenna cannot satisfy the demand of the large-caliber and ultra-large-caliber antennas. It is necessary to design a new kind of antennas to satisfy this demand. This paper introduces the geometrical topology and the necessary conditions of the double-ring deployable truss. And due to the normal performances of the antenna, staring with the dynamic analysis, the best height and number of sides of the truss were obtained. Finally, the deploying mechanism of the inner ring and the outer ring of the double-ring deployable truss were introduced in details.On the basis of the characteristics of the double-ring deployable truss and theory of Moore-Penrose, multi-body dynamic was utilized to analyze the deploying process. Some special constraints of the double-ring deployable truss were added on the basis of the formal single-ring deployable truss. Simulation was taken out in C++Visual2008. To verify the self-programmed procedure, the simple pendulum and deployable bridge were tested. And the results were compared with the calculated values by theory which gives the validity. Moreover, the self-programmed procedure can save much time when modeling and calculating. At last, each state and coordinates of all the nodes can be obtained by numerical simulation of the deploying process of the double-ring deployable truss.Different models with different calibers and initial heights can be obtained by parameterization. By finite element method, modal analysis of the double-ring deployable truss and the first frequency of the double-ring deployable truss in each deploying state were obtained. By comparisons of the results with ANSYS, the validity of the self-programmed procedure was verified.SQP method and GA were used for the few variables in the optimization. In order to show the advantages of the double-ring deployable truss, minimum weight optimization with frequencies constraints is established. By optimization, the minimum weight of the single-ring deployable truss and double-ring deployable truss were obtained separately. We can see that the double-ring deployable truss can save weight over the single-ring deployable truss with constraints satisfied.Not only the characteristics of the double-ring deployable truss in the final deployed state were important, the characteristics of the double-ring deployable truss in the initial folded state and each deploying states were also important. Therefore, these dynamic constraints were added into to optimization model. By optimization, the minimum weight can be obtained with all the dynamic constraints in the initial folded state, each deploying states and the final deployed state satisfied.The equation of the RMS of the reflecting surface was established according to the theory of the metallic reflector. Therefore the RMS constraint was also added into the optimization model and the optimal result was obtained. Then different numbers of the design variables were chosen to obtain the different minimum weights. The best number of the design variables was chosen to design and manufacture the model, which gives some foundations for the design of antenna. A scaled model was designed by the optimization method researched in this paper, and a set of systems which can eliminate the gravity of the antenna was also designed for the experiments in the future.