The natural property of a three-axis attitude stabilized spacecraft is investigated by simplifying it as a rigid central body jointed with 4 solar panels in this paper. For the spacecraft composed of a rigid central body and flexible panels, the Rayleigh-Ritz method is employed to obtain global modes which are explicitly functions of space coordinates and are useful for the modeling of lower-order discrete dynamic equations and design of active vibration controllers for the system. The Gram-Schmidt process is used to construct a set of characteristic orthogonal polynomials as the displacement field of the solar panel. Lagrange multipliers are introduced to describe the constraint at joints. The characteristic equation of the whole system is derived through the Rayleigh-Ritz procedure. Then, natural frequencies and corresponding global modes of the spacecraft with jointed panels are obtained. Taking the natural frequency obtained from the finite element method as a reference value, the process of getting natural frequencies is validated by comparing results obtained with those from the finite element method. Moreover, an excellent convergence and high accuracy of the present method is demonstrated by a very good agreement between results from ANSYS and theoretical method proposed here. Finally, parametric studies on characteristics of the spacecraft are conducted. The interesting mode shift phenomenon is observed when parameters of the spacecraft are changed.

通过将三轴姿态稳定的航天器简化为与四个太阳能电池板连接的刚性中心体，来研究其自然特性。对于由刚性中心体和柔性面板组成的航天器，采用Rayleigh-Ritz方法获得全局模式，这些模式是空间坐标的显式函数，可用于低阶离散动力方程的建模和主动振动控制器的设计对于系统。Gram-Schmidt过程用于构造一组特征正交多项式作为太阳能电池板的位移场。引入拉格朗日乘数来描述关节处的约束。整个系统的特征方程是通过Rayleigh-Ritz程序导出的。然后，获得了具有连接面板的航天器的固有频率和相应的整体模式。以有限元法获得的固有频率为参考值，通过与有限元法获得的结果进行比较，验证了获得固有频率的过程。此外，通过ANSYS的结果与此处提出的理论方法之间的良好一致性，证明了本方法的出色收敛性和高精度。最后，对航天器的特性进行了参数研究。当航天器的参数改变时，观察到有趣的模式转变现象。通过比较与有限元方法获得的结果，可以验证获得固有频率的过程。此外，通过ANSYS的结果与此处提出的理论方法之间的良好一致性，证明了本方法的出色收敛性和高精度。最后，对航天器的特性进行了参数研究。当航天器的参数改变时，观察到有趣的模式转变现象。通过比较与有限元方法获得的结果，可以验证获得固有频率的过程。此外，通过ANSYS的结果与此处提出的理论方法之间的良好一致性，证明了本方法的出色收敛性和高精度。最后，对航天器的特性进行了参数研究。当航天器的参数改变时，观察到有趣的模式转变现象。