Study On Bearing Preload Of Space Joint And Its Dynamic Characteristic

Spacecraft works in the environment of high and low temperature, high vacuum and high-radiation, and its structural characteristic is effected by the space environment. In this dissertation space joint is researched, The bearing rigidity characteristic in space environment is studied to determine the manner and value of its preload, preventing the preload of space joint becomes too low so that the preload is unloaded, or too high so that the space joint is blocked, ensuring the safety and reliability of the space joint.In this paper the analytic solution of space joint bearing is gained based on the classical Hertzian theory. The numerical solution of space joint bearing is gained based on the FEM theory, and the coordinate deformation and friction are investigated. Then the practical value of the bearing rigidity is obtained by experiment. Comparison of three results show that the Hertzian analytical solution does not apply to analysis of space joint bearing, while a good agreement between the FEM and experimental results is found.The thermal condition of space joint in space environment is studyed based on the heat transfer theory and thermal resistance network theory. The heat generate rate of space joint bearings and temperature fields of space joint are developed. The means and approach of space joint bearings'preload is determined based on the working environment and condition of space joint. The joint displacement and change of bearing stiffness are analysed by the FEM structural-thermal coupled analysis. Concrete structure is designed to obtain the desirable preload, and corresponding experiment is done to verify the agreement between practial and theoretical preload value, and the rationality of the design preload value.The dynamic characteristic analysis of space manipulator is done on the condition of preloading. The mode parameter and mode shape is obtained to verify whether it meets the design target. At last vibration testing is implemented to verify the correctness of FEM and the adaptability of space manipulator to space vibration environment.Bearing Preload Technology is studyed and used widely, but few study is relative to space environment. This dissertation can be the reference of the space machine design which refer to bearing preload, and can also be used to design the terrestrial machine in large difference of temperature. And the method of achieving precise preload presented in this paper can be used in other fields where precise preload is required.