The Analysis And Study Of Flexture Spinning Seatellite’s Angle Momentum Transition Process

With the development of aerospace technology,the modern large-scale spacecraft often appear with large flexible structures,such as the great antenna,solar panels,truss structure.The spacecraft is becoming more and more complex.What is more,the large overall motion of the spacecraft has become more complicated and diversiform,such as the spacecraft’s orbit transfer and attitude maneuver.And the elastic deformed motion of the flexible structures aroused by the large overall motion of the spacecraft can never be neglected.Because of the coupling of the two motions,making the dynamic analysis of the whole spacecraft is more difficult.And the traditional rigid modeling methods can never meet the requirements of modern spacecraft dynamics analysis.For example,the spin motion of quasi rigid bodies must satisfy the maximum axis principle.Thus,it is important of us to research the coupling of the large overall motion and the elastic deformed motion.This paper made the spin satellite with flexible solar arrays as the specific research object to study angular momentum transfer process of a flexible spinning satellite after minor perturbations.Firstly,the paper has derived the rigid-flexible coupling dynamic equations of flexible spacecraft systems based on the theory of mixed coordinate method.Because the description of three-dimensional space motion is complex.And for the case of the convenience of subsequent mathematical analysis,this paper has made some mathematical simplification of the rigid-flexible coupling dynamic equations.Another difficulty of the modeling process is the determination of the rigid flexible coupling matrix.In order to analyze the dynamic characteristics of the complex structure attachment such as flexible solar array,in this paper,the finite element modeling method is used.The rigid flexible coupling coefficient matrix of satellite is calculated on the basis of mathematical formula.In order to simulate and analyze the influence of various parameters on satellite angular momentum transfer,this paper first compare numerical methods for several stiff differential equations,including four common method of MATLAB itself and implicit two stage and four order Runge-Kutta algorithm which was programed by this paper.In this paper,the applicability and efficiency of the five numerical algorithms are compared.By comparing the numerical simulation results calculated by the implicit multistep method,this paper analyzed the influence of the structural damping of the solar array,the density of the solar array,the rotation inertia matrix of satellite,the mass distribution of satellites and the Initial motion condition on the angular momentum transfer of flexible spinning satellite.The research of this paper find that the angular momentum transfer of satellite is not sensitive to the damping parameters of the array structure.But it is very sensitive to satellite rotation inertia and initial conditions,which is mainly due to the mass of solar panels are extremely small,what is more,the vibration of the flexible solar panel is a slight vibration.The kinetic energy dissipation of the satellite is a very slow process.In other words,it took a long time for the satellite to return to its steady spinning state.And depending on the vibrations of solar arrays,the spin satellite can eventually achieve a steady motion state spinning around the maximum inertia principal axis,but not the initial state of motion.A slight offset appeared of the flexible satellite’s spin axis.The maximum axis principle is not a strict asymptotic stability.