Deployment Dynamics Of The Large-scale Hoop Truss Antenna Of Satellite

In recent years,the space community has paid much attention to the development of the large-scale hoop truss antenna of satellite so as to improve the quality of telecommunication of high frequency and the Earth observing of high resolution.The antenna of this type is composed of one or two stretchable arms,a deployable hoop truss and a flexible mesh reflector.The deployment process of such an antenna on orbit involves many sophisticated dynamic problems.However,it is impossible to testify the deployment process of the antenna on ground since the micro-gravitational and vacuum environment can hardly be realized.In order to ensure both smooth deployment and asympototic stability of the antenna on orbit,hence,the numerical simulation of the deployment dynamics and the prediction of the dynamic responses of such an antenna are of great significance during the design phase of the antenna.During the research process of the large-scale hoop truss antenna of satellite,an accurate and effective dynamics model has to be built.The main difficulty to establish the deployment dynamics model of the antenna is to describe the coupled dynamics involving both overall motion and large deformation.As has been reported,the conventional methods of flexible multibody dynamics based on the small deformation assumption are not capable of reflecting the coupled dynamics.The Absolute Nodal Coordinate Formulation(ANCF)can accurately describe the coupled dynamics involving both overall motion and large deformation so as to predict the deployment dynamics of the mesh reflector effectively.Furthermore,the ANCF can lead to a constant mass matrix and constraint equations that are easy to express.However,the increased scale of the antenna gives rise to the computational burden,which brings a significant challenge to predict and improve the dynamic characteristics of deployable structures.Moreover,the form-finding of the mesh reflector to design a reflective surface with accurate geometrical facet approximation is indispensable in the process of reflector design.In order to deal with the deployment dynamics of the large-scale hoop truss antenna of satellite,based on the Absolute-Coordinate-Based(ACB)method,the form-finding analysis of mesh reflectors,the parallel computation methodology of the differential algebraic equations for the multibody system and the asynchronization phenomenon during the deployment process are studied in this dissertation.The major contributions of the dissertation can be summarized as follows.1.The main components in the large-scale hoop truss antenna of satellite are described in detail.Therein,the typical geometrical configurations of the parabolic reflector and the generation of the mesh pattern are introduced.The finite elements of the ACB method are used to establish the antenna model.The benchmark examples of static analysis are used to verify the validation of the nodal coordinate transformation technique.2.Based on the improved iterative Force Density Method(FDM)and the Minimum Norm Method(MNM),an effective form-finding methodology considering the flexibility of the hoop truss is proposed so as to optimize the tension force distribution of the mesh.Using the method,the form-finding analysis of the AM3 mesh is performed and the form-finding results indicate that the flexibility of the supporting hoop truss should be considered for the form-finding of large aperture antennas.3.To improve the computation efficiency of the dynamics simulation of the large-scale hoop truss antenna of satellite,a recursive strategy based on the Schur Complement method and the multilevel decomposition approach is proposed.Using the parallel computation methodology,the dynamic simulation of a large scale rigid-flexible multibody system is efficiently completed based on the Message Passing Interface(MPI).Two numerical examples are presented to validate the accuracy and efficiency of the proposed parallel computation methodology.4.Based on the ACB method,the deployment dynamics of the hoop truss antenna is predicted.The deployment of the system can be divided into three phases.The effects of these deployment phases on the attitude of the satellite body are analyzed.5.A computational program is developed via the Fortran language to analyze the deployment dynamics of the large-scale hoop truss mesh antennas.Using the program,the dynamic simulation of a complex reflector is performed.The effect of the tension forces in the cables of the mesh reflector on the deployment process is studied.The factors that induce the asynchronization phenomenon during the deployment of the antenna are discussed.