Abstract: The dynamic behavior and rigid-liquid-flex coupling effect of the complex spacecraft system carrying plate-type flexible appendages and liquid-filled arbitrary axisymmetrical tanks with curved wall are investigated in this paper. The plate-type flexible appendages attached to spacecraft are discussed by the Kirchhoff-Love plate theory, and the coupled vibration equations of the flexible appendage are drawn from the D’Alembert principle. By the spatial discretization and truncation, the differential equations reduce to the nonlinear discretized state equations, which are convenient for numerical calculations. The carrier velocity potential function of the liquid is obtained by the motion equation of a representative point in the tank, while the relative velocity potential function can be expressed by the Gauss hypergeometric series. By using the Hamilton’s variational principle, the governing equations of the liquid sloshing coupled with the spacecraft motion and modal coefficients of the relative velocity potential function can be derived. The motion equations of the coupled spacecraft system are deduced by using the Lagrange’s equations in terms of general quasi-coordinates. The efficiency of the dynamical model of the coupled spacecraft system is examined through numerical simulations. The results indicate that the rigid-liquid-flex coupled effect of the spacecraft system exhibits complex dynamical behaviors, the effects of the fuel sloshing and the flexible appendage vibration should be fully considered in the process of dynamic modeling and analysis of complex spacecraft system. The installation position of the flexible appendage has great influence on the dynamic behavior

Key words: Liquid sloshing, Flexible appendage, Low-gravity environment, Liquid-filled spacecraft, Rigid-liquid-flex coupled dynamics