STUDY ON GLOBAL MODE DYNAMIC MODELING AND EXPERIMENT FOR A SOLAR ARRAY OF THE FLEXIBLE SPACECRAFT

Modern flexible spacecraft are usually installed with large solar arrays to provide the power needed for the operation of the spacecraft in orbit. The solar arrays are expanded in orbit and locked into hinged multi-panel structures, and the characteristics such as light weight, large span, and low stiffness make the issues on the study of low frequency and nonlinear vibration become more and more important. The key process of dealing with the vibration for such a kind of structure is to establish the exact nonlinear dynamic model of the system. In this paper, an analytic extraction method of the global mode of the multi-panel structure is presented, and the natural frequencies and the global analytic mode functions of the solar array are obtained. Considering the nonlinear stiffness and friction moments of the hinges, and the nonlinear dynamic model of the system can be obtained by the global mode discretization. The nonlinear characteristics of the solar array under periodic excitation are studied. The experimental researches on the solar array are carried out, and the mode shapes are obtained by hammering tests, and the sinusoidal sweep excitation is applied by the vibration table. The physical experimental results are compared with the theoretical results, so as to verify the rationality and accuracy of the global mode dynamic modeling method. The experimental results show that the structural parameters such as hinge stiffness have a great influence on the inherent characteristics of the system, and the existence of hinges will make the dynamic response of the solar array appear nonlinear phenomena such as jump. Global mode dynamical modeling method can well solve the difficult problem of obtaining the analytical global mode for the multi-panel structure with the non-classical boundaries. The global mode of the system can reflect the real elastic vibration mode of the parts in the system, and the established dynamic model is low-dimensional and high-precision. It has important reference value for nonlinear dynamic modeling of complex composite structures.