The Design Of Micro-Satellite Propulsion System And Numerical Simulation Of The Forming Of TB8 Hemispherical Part

With the development of spaceflight engineering, more and more micro-satellites have adopted propulsion system. As one of the important components of micro-satellite, propulsion system provides control moment for the satellite's attitude and orbit control associated with the control system. Propulsion system has great effect on the satellite's performances such as life-span, reliability, mobility and accuracy of keeping position. So the development of small, light and cheap propulsion system is of great significance on engineering practice.According to the mission requirements of propulsion system of micro-satellite, liquefied ammonia gas propulsion system was selected and the scheme of the system was designed after the comparative work of the major propulsion systems was completed. On the basis of scheme design, the structure of the propulsion system, constituted of the structure of the bearing board of the propulsion system and other components such as the sustainers of the thruster and propellant tank, was designed in detail. The inner part of the propellant tank is one ultra thin TB8 spherical part which is made of two hemispherical parts by welding technique. The defects such as wrinkling and cracking often appear in the forming of the ultra thin hemispherical part. To improve the forming process in engineering practice, the numerical simulations of the hydraulic rubber forming and stamping forming of the ultra thin TB8 hemispherical part were carried out respectively. The simulation results show that the wrinkling in hydraulic rubber forming process was very difficult to eliminate, but were suppressed effectively in stamping forming process and thickness distribution of blank was also more uniform and sound. The parameters such as gap between the blank-holder and die, the height of the straight-wall of die, the radii of die and their influence on the deformation process were investigated carefully in the simulation of stamping forming process and the optimum parameters obtained, which may be used to die design and process design.