Design and Analysis of Propellant Tanks Support Structure for an Advanced Spacecraft

Abstract

This paper proposes a new type of configuration to support the propellant tanks in large size spacecrafts. Research in space industry over the last decade is focused on reducing the launch cost of the spacecraft. The main objective of this project work is to develop new concept of propellant tanks support structure for 6 ton class spacecraft. This configuration has four propellant tanks (2 oxygen tanks & 2 fuel tanks) which are mounted in polar form outside the central thrust cylinder and are supported by a flat rigid panel and two struts at fixed end and flat deck at free end. The stiffness requirements of advanced spacecraft are > 8Hz, >27Hz and >30Hz for global lateral mode of the spacecraft, oxygen tanks axial mode and fuel tanks axial mode respectively. For support structure various configurations, were worked out to meet stiffness requirements. The configurations considered are Honeycomb Sandwich panel, Honeycomb Sandwich panel embedded with doublers at tank attachment zone, Honeycomb sandwich panel embedded with rectangle beam at tank attachment zone and Honeycomb sandwich panel with circular struts at tank attachment zone. Design iterations were carried out for above four configurations and suitable configuration was finalized. Static analysis was also carried out for the given load cases to determine strain, Hoffmann failure index, SR and MOS for the composite central thrust cylinder. The geometric modeling of the propellant tanks support structure and main parts of the advanced spacecraft for all the four configurations were modeled by using UNIGRAPHICS-Nx6® and analysis carried out using MSC/PATRAN®, MSC/NASTRAN®.