Department of Mechanical Engineering
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Browsing Department of Mechanical Engineering by Author "Li, Gangqiang"
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Item Open Access Flight Dynamics and Control Strategy of Electric Solar Wind Sails(American Institute of Aeronautics and Astronautics, 2019-11-27) Zhu, Zheng H.; Li, Gangqiang; Du, ChonggangThis paper studies the flight dynamics and control strategy for electric solar wind sails based on the nodal position finite element method, where the coupling effects between tether dynamics and the electrical field are considered. A modified throttling control strategy is proposed to control the attitude of electric sails by modulating individual tether voltage synchronously with the spinning motion of the sails. The effects of four critical physical parameters (tether numbers, tether length, sail spin rate, and mass of remote units) are investigated. The results show that the effect of the relative velocity of the solar wind has a significant effect on the spin rate of the sail in attitude maneuvering, which in turn affects the attitude dynamics and orbit motion of the sail. Numerical results show that the proposed control strategy work successfully stabilizes the spin rate of sail when the new type sail is adopted.Item Open Access Three-Dimensional High-Fidelity Dynamic Modeling of Tether Transportation System with Multiple Climbers(American Institute of Aeronautics and Astronautics, 2019-03-04) Zhu, Zheng H.; Li, Gangqiang; Shi, GefeiThis paper studies the dynamics of a tether transportation system by the nodal position finite element method in the framework of an arbitrary Lagrangian–Eulerian description. Material coordinate is introduced as a state variable that is decoupled with the position coordinate. The movement of climbers is represented by moving nodes associated with the material coordinates. It is integrated into the finite element method by a variable-length tether together with a process of dividing and merging elements. The dynamic behavior of the tether transportation system with multiple climbers is studied. The results show that the elastic-flexible tether model is able to capture the high-frequency oscillation of the tether transportation system. The oscillation could have an adverse effect on the safe operation of the tether transportation system, especially in causing fatigue failure of the tether, and must be considered.