The influence of joint eccentricity on the foldability of four deployable structure systems

The study of deployable structures has been carried out traditionally by simplifying their constituent elements—joints and rods—to ideal entities. However, in this paper the dimensional thickness of these elements is taken into account, in order to evaluate their incidence on the foldability of four deployable structure systems. We have examined the eccentricity that occurs specifically at the joints themselves. Our study ultimately characterizes the incidence of this factor by defining noteworthy parameters common to both tube bundle and scissor systems, enabling us to establish a comparison and draw relevant conclusions.

Comparison on the Tribological Properties of Roller and Guide Tribo-Pair Used in Antenna Deployable Structure

The tribological properties of roller and guide tribo-pair are important for the design of deployable structure for space-borne perimeter truss antenna. In this study, carbon fiber epoxy resin composites are used as the guide material; while polyimide and GCr15 steel are used as the roller material. Then, friction coefficient of polyimide ball and GCr15 steel ball against carbon fiber epoxy resin composites disk were compared and investigated on the high-temperature, ball-on-disk tribometer under different operating conditions, respectively. The wear morphology of disk was measured by laser scanning confocal microscope. The results show that the friction coefficient of the polyimide ball against carbon fiber epoxy resin composites tribo-pair has better tribological properties. Meanwhile, the friction coefficients of this pair are mainly depend on abrasive wear under low pressure and velocity conditions while the adhesive wear has dominated influence on the friction coefficient for high pressure and velocity conditions. Besides, the tribological properties of carbon fiber epoxy resin composites are mainly affected by ploughing of surface roughness at low temperature, while by surface debonding at high temperature.

Hanger forces optimization of ground test device on deployable structure

When using suspension method to simulate the microgravity environment, part of the hanger forces are used to offset the influence of gravitational field on the deployable structure, while the other part produces additional forces that affect the driving forces and precision of the deployable structure. In order to reduce the adverse effect of hanger forces, and avoid the construction of complex finite element theoretical model, an optimization method based on adaptive genetic algorithm with MATLAB and Nastran co-simulation is proposed. Then, the hanger forces are optimized, and the deployable structure deformation has been reduced 49%. It suggests that the adverse effect of hanger forces has been effectively reduced and the proposed optimization method works well.

Analysis and control of state jump in space deployable structures under alternating temperature loads

State jump has been experimentally observed in space deployable structures working in alternating temperature environments. State jump is a phenomenon in which the geometric shape of the structure changes after the temperature loading and unloading process, which makes the working accuracy of the space deployable structure intrinsically unpredictable. This paper aims to investigate the causes of this state jump phenomenon and seek measures to reduce its effect. Firstly, the static multiple-stable-state phenomenon resulting in state jump is analyzed for clearance joints in deployable structures. Then, an equivalent model consisting of a variable stiffness spring and a contact element for state jump analysis is proposed, which is verified by a finite element simulation. Influence factors and control methods of state jump are further explored. Finally, numerical results of a space deployable structure of an umbrella-shaped antenna show the effectiveness of the developed analytical method.