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.

Research on Minimum Pressure Angle of Bennett Linkage

Space deployable structures that are constructed by the single loop over-constrained linkages have been extensively applied in the fields of aerospace and construction. The pressure angle regarded as an important index to measure the performance of the basic units has attracted more and more attention. The kinematic model of the Bennett linkage is studied by the D-H matrix and the analytic formula of the pressure angle has been deducted through kinematic equations. The rule of the Bennett linkage has been discovered that the minimum pressure angle occurs while the input angle equals nπ + π / 2(n ∈ N). According to the linkage configuration at the input angle of π / 2, the geometric meaning is revealed that the minimum pressure angle of the linkage is the same as the twist angle of the joint axes of the output link. Finally, conclusions can also be drawn that the smaller the twist angle of the output link is, the smaller the minimum pressure angle will be. The research enriches the kinematics of Bennett linkage and provides a reference for its engineering applications.

Design and experiment of a passive damping device for the multi-panel solar array

With the space technology development, large flexible space deployable structures have been used widely. Studying on the vibration control for large flexible space deployable structures becomes very important. In this study, a novel passive vibration damping device is developed for the multi-panel sun-orientated deployable solar array. Its upper strut contains a viscous damper while the lower strut is rigid. The device is lockable and located near the solar array root hinge to increase the structural damping without reducing the fundamental frequency. This design will not influence the original functions of the solar array, such as folding, deploying, and sun tracking. The corresponding finite element models are established, and the properties of the damping device are investigated by modal analysis and transient response analysis. The damping mechanism design for a certain type of solar array is presented. The associated modal tests based on a solar array test sample verify the effectiveness of the device. Conclusions are drawn to help define design guidance for future damping device implementations.