Modeling of spacecraft with flexible solar panel considering thermally induced motion
Thermally induced motion of flexible solar panel have significant impact on attitude dynamics and control when the spacecraft experience eclipse transitions. Based on angular momentum theorem thermally induced attitude dynamics of rigid hub with a flexible solar panel is developed. The principle of thermally induced vibration is explained. Thermally induced disturbance toque which initiates attitude error of control system is obtained. Flexible modal response is analyzed with different position of solar panel when satellite enter or exit eclipse. Numerical simulations illustrate that thermally induced disturbance toque mainly distort yaw and roll axis attitude of spacecraft.
Thermally-induced bending-torsion coupling vibration of large scale space structures
In this paper, a finite element scheme is developed to solve the problem of thermally-induced bending-torsion coupling vibration of large scale space structures, which are usually composed of thin-walled beams with open and closed cross-section. A two-noded finite element is proposed to analyze the transient temperature field over the longitudinal and circumferential direction of a beam. Since this temperature element can share the same mesh with the two-noded beam element of Euler–Bernoulli type, a unified finite element scheme is easily formulated to solve the thermal-structural coupling problem. This scheme is characterized with very strong nonlinear formulation, due to the consideration of the thermal radiation and the coupling effect between structural deformations and the incident normal heat flux. Moreover, because the warping is taken into account, not only the thermal axial force and thermal bending moments but also the thermal bi-moment are presented in the formulation. Consequently, the thermally-induced bending-torsion coupling vibration can be simulated. The performance of the proposed computational scheme is illustrated by the analysis of the well-known failure of Hubble space telescope solar arrays. The results reveal that the thermally-induced bending-torsion coupling vibration is obviously presented in that case and could be regarded as a cause of failure.
Buckling and Quasistatic Thermal- Structural Response of Asymmetric Rolled-Up Solar Array
Analytical studies for buckling and the quasistatic thermal‐ structural response of an asymmetrical rolled-up solar array of the type used on the Hubble Space Telescope are presented. A buckling analysis assuming asymmetric loading because of geometric asymmetry establishes critical buckling forces and buckling modes. Quasistatic thermal‐ structural responses of the solar array subjected to the sudden radiation heating typical of a night‐ day orbital transition are also developed. Computations conducted for the Hubble Space Telescope show that the solar arrays were deployed with a solar blanket prestress that would induce global torsional buckling. Numerical computations for the quasistatic response show that thermally induced bending‐ torsional deformations would cause bending moments in the solar array’ s booms consistent with the local buckling failure observed by the astronauts.