Thermal-Structural Analysis Of Spacecraft Solar Panels In Orbit Under Various Operating Conditions

Solar panels have played a key part through the process of spacecrafts'operation in orbit, providing most of the electrical power needed by space vehicles. So the thermal state of solar panels in orbit has been investigated since years ago. However, the previous research work of the thermal-structural analysis mainly concentrated on full load condition, and the research work of thermal-structural analysis under half load condition existing in the spacecraft's practical operation has not been reported. Consequently, the thermal-structural analysis of solar panels with rigid substrate under two conditions of full load and half load are conducted in this thesis, including its temperature distributions, thermal stresses and thermal deformations. The main contributions of the work are as following:The rigid substrate of solar panels is treated as an orthotropic plate. Considering the structure of honeycomb sandwich plate with the adhesive layer and the carbon fiber grid plane, its equivalent orthotropic thermal conductivity is deduced based on a new equivalent thermal resistance method. The new method can be utilized in the engineering work, which provides necessary input parameters for the further thermal analysis of solar panels.In order to obtain temperature distributions of solar panels under full load condition, a three dimensional thermal model is established. The control volume method is used to discretize the three dimensional transient temperature control equations, the element CG method is employed to deal with the heat exchange items among the nodes, the Oppenheim method is adopted to construct radiative matrix to calculate the heat flux and radiative heat exchange between surface elements, and Newton-Raphson method is employed to simplify the nonlinear terms existing in the calculation of radiative heat exchange. Finally, the highly-accurate bi-conjugate gradient solver is used to solve the whole discrete temperature equation set.On the basis of thermal analysis of solar panel under the full load condition, the thermal analysis under half power condition is proposed and investigated by altering the effective solar absorptivity. Through this method, the thermal model of solar panels for full load condition can be used for the various load condition. Based on the thermal analysis results, the temperature distributions of solar panels components in quasi-static conditions are studied, inculing its cell, right side and backside. The temperature difference through the thickness of solar panels and its first time derivative are discussed, the temperature distributions of solar panels at three typical moments are predicted, including the moments for the shadow into sun, the highest temperature and the sun into the shadow. Also the effect of the initialized temperature condition on the simulated results is discussed.To corroborate the numerical method adopted in this thesis, a solar panels model of KOMPSAT in the previous research is established by this method, and present simulation results fit well with those in the previous work.To analyze the thermally induced stresses and deformations, a three dimensional structural finite element model of solar panel is established with the temperature field from the above thermal analysis. The calculated temperatures are loaded into the structural model by the indirect coupling of thermal-structure through temperature mapping. The thermal stresses and thermal deformations of solar panels at three typical moments are investigated. Thermal deformations of the solar panels in the whole period are studied, and results show that the thermal deformations of solar panels are mainly caused by the transient temperature difference through in the thickness direction. Finally, based on the results of the thermally-induced structural analysis, effectively thermal control measurements are proposed to reduce thermal stresses and thermal deformations.