A Study Of Thermal Fatigue Of Solar Array

The thermal deformation of the thin-walled tubes under the heat flux from the sun and other celestial bodies, such as the main boom of solar array of the Hubble Space Telescope, is extensively concerned. On the base of Thornton theory, the temperature fields for the main booms of solar array of the Hubble Space Telescope are simulated by using the finite element program ABAQUS, which mainly involving the temperature increased and descended due to sunrise and sunset, respectively. Simultaneously the thermal deformation and the stress are calculated. The results in this thesis agree well with the analytical solution of Thornton and the numerical results calculated by Ding Yong from Tsinghua University. Therefore, the methods in this thesis can be used to simulate the temperature field and thermal deformation accurately, which can be further developed to the analysis of the vibrations induced thermally and the thermal fatigue. The full fatigue life of the main boom of solar array of Hubble Space Telescope is calculated by software of Fatigue and the thermal stresses, the result agrees very well with the experimental result of the solar array material completed by NASA.The conclusions from above research are as follows.(1) During the calefactive period, the average temperature of the main boom of solar array becomes stable after being exposed to the sunshine for about 15 minutes, and the average temperature under the stable status is about 403°K (equivalent to 130℃). During the descending period, the temperatures of the upper and the lower surface of the main boom become same in about 150 seconds, and the average temperature of the cross section of the boom will be similar with the environmental temperature in about 1000 seconds.(2) When subjected to the heat flux from the sun, the temperature distribution on the cross section of the main boom of solar array is presented as a cosine function. While the sunshine time is increased the temperature of the main boom is arisen gradually. When the three transmitting heat processes, absorbing heat from the sun to the upper surface of the boom, conducting heat from the upper to the lower surface and emitting heat from the whole boom to the airspace, maintain a dynamic equilibrium, the temperature in the whole boom will reach a stable status in 15 minutes.(3) Subjected to the thermal cycle due to sunshine and sunset, there is a periodic thermal stress inside the main boom of solar array of the Hubble Space Telescope. The full fatigue life of the main boom of solar array is predicted in this thesis reasonably, the result agrees very well with the experimental result.