This paper investigates a whole process for the form-finding analysis of cable net reflector antennas with creep and recovery behaviors in consideration. Both the force-density and nonlinear finite element methods are extended together to establish and solve the nonlinear optimization model for the form-finding analysis. First, the equal force-density method is applied to the form-finding analysis of the initial cable net configuration, in which the creep and recovery behaviors are not taken into account. Second, the nonlinear force-density method and Schapery’s nonlinear viscoelastic theory are used to build the mathematical model of the creep and recovery behaviors of cable net reflector antennas, and the incremental-iterative method is then adopted to solve such a mathematical model. Based on aforementioned two steps, the nonlinear optimization model is established, and it is solved by the inverse iteration algorithm. Eventually, the hoop truss reflector antenna is presented as a numerical example to illustrate the efficiency of the proposed method for the form-finding design of the creep and recovery behaviors of cable net reflector antennas.

The umbrella cable-net structure is one of the most popular forms for deployable space reflectors and has been successfully applied to many in-orbit deployable antennas. The umbrella ribs only provide open support for the cable net, so designing the geometric shape and the internal tension of the umbrella cable-net structure is complex. This paper suggests several double-layer cable-net structures for a deployable umbrella reflector. First, a typical composition of the umbrella reflector was introduced and the design basis of its geometric topology was further discussed. Then, two methods for the static equilibrium analysis of the cable-net structure were introduced for the mechanical calculation of the cable-net structure. Next, three types of the cable-net structure—wedge-shaped/wedge-shaped (W/W), triangular/triangular (T/T), and triangular/wedge-shaped (T/W)—were put forward. The three cable-net types were applied to a reflector and their performances were analyzed and compared with each other to demonstrate their feasibility and applicability.

Cable length adjustment is a critical step to minimize the shape error of cable-net reflectors. The adjustment requires tedious repetitive work, but the surface accuracy is often unsatisfactory because of inevitable operating error and modeling inaccuracy. To solve this problem, this work proposes a target-approaching and procedural-learning method. At the initial stage of the adjustment process, the target-approaching method is proposed to ensure the shape error is improved and that adjustment data are generated. Then an online prediction model is built by sensitivity analysis and least-squares support vector machine. On this basis, a multidimensional forward-backward algorithm is applied to calculate the optimal adjustment amounts in order to achieve fast convergence of adjustment accuracy. Finally, the proposed method is verified by both numerical simulation and prototype experimentation. The results show that the proposed method can well reflect the adjustment characteristics of cable-net reflectors, effectively improve shape accuracy, and greatly shorten adjustment time.

A cable-frame structure typically has low damping and a low fundamental frequency and is modally rich. It is likely to generate sustained vibration when disturbed. Unwanted vibration of such a structure must be caught and controlled to ensure its structural safety and design performance. To overcome the disadvantages of high frequency distortion and modal truncation arising from modal control methods, wave control methods have been suggested. However, they generally involve establishing and solving numerous wave equations, an expensive procedure that may make the vibration control for large and/or complex structures inefficient or even impractical. This study presents a simple analytical approach for the vibration control of large cable-frame structures. The approach is divided into two stages. First, the exact frequency-domain solution is obtained by a dynamic stiffness method in which the infinite degrees of freedom of each flexible component are reduced into only several degrees of freedom at its two endpoints. Second, formulas for calculating the local wave and power flow are deduced based on the global exact solution so that the local wave control information can be extracted from the global response solution. Using this approach, the dynamic response and wave and power flow analysis are carried out for two typical cable-frame structures, leading us to suggest several control measures for suppressing vibration. The approach, if proven to be effective, can be readily applied to vibration control of large cable-frame structures.

Affected by the alternating temperature field in space, the space deployable structure produces large thermal deformation, which leads to the deterioration of surface accuracy and performance. To a...

To meet the increasing communication demands, the satellites need to be equipped with the high-accuracy and large-aperture antennas. One of the effective methods to construct the modular antennas with ultra-high accuracy and ultra-large aperture is on-orbit assembly technology. During the on-orbit assembly missions, the assembly error is a key factor to affect the surface accuracy of the modular antennas. This paper studies the node design of each module and the assembly error analysis of the modular antennas. A design method of the module nodes is presented with consideration of the assembly gap between two modules. Meanwhile, a soft connection mechanism is designed to ensure the mobility among the assembly modules. To investigate the transmission law of the assembly errors, an analytical model of assembly error is derived based on the exponential product method. In order to establish the deformation surface with rotation and displacement assembly errors, an error ball concept is proposed by the analytical model. To decrease the assembly errors, the actuators are installed among some modules. Moreover, an adjustment method is proposed to obtain the adjustment amounts of actuators. Finally, the correctness of analytical model and the effectiveness of the adjustment method are demonstrated by the numerical simulations.