Effects of time-varying mass distribution on orbit-attitude-vibration coupling characteristics of dumbbell-shaped spatial structure

During the on-orbit servicing for the large flexible spacecraft, the time-varying inertia induced by the internal mass transfer within the spacecraft affects the stability of the coupled vibration and attitude. To reveal the above dynamic perturbation mechanism, an on-orbit large dumbbell-shaped model with time-varying orbit-attitude-vibration-inertia coupling characteristics is developed based on the Hamiltonian variational principle. Then, a numerical scheme combining symplectic Runge-Kutta and generalized multi-symplectic methods is constructed to solve the above model. The structure-preserving properties of the proposed scheme are verified by the tiny errors recorded during simulations. In the simulations, the perturbation mechanism of orbit-attitude-vibration coupling behaviors excited by time-varying mass distribution in the system is revealed, which is related to the duration and rate of the internal mass transfer. Specifically, short-term mass transfer causes a high frequency attitude oscillation with an increasing amplitude, while long-term mass transfer leads to the attitude instability. Additionally, the critical mass transfer duration maintaining the stable attitude motion as well as the decay-increase-decay pattern of the beam’s transverse amplitude related to the mass transfer rate are revealed, respectively. The proposed structure-preserving method provides a strategy for predicting the attitude and structural dynamics of on-orbit dumbbell-shaped spacecraft during the internal mass transfer.