Effect of non-uniform temperature Held under sunshine on the structure supporting the reflector of a large radio telescope-FAST

The effect of non-uniform temperature field under sunshine on the structure supporting the reflector of the FAST, Five-hundred-meter Aperture Spherical Telescope, is studied. Based on the thermal analysis module of ANSYS, an integral parametric finite element model is established for the structure supporting the FAST reflector and its measured landform, and the boundary conditions of periodic air temperature, solar radiation, long-wave radiation and shadow of the surrounding environment, etc., are computed each half hour in a cloudless day in summer as one of the worst-case weather conditions, then the transient temperature analysis under sunshine which sustains several days with a rational initial structure temperature field is terminated when the temperature everywhere is convergent to the results for the day before, subsequently the related temperature deformation and stresses are computed. Finally, the variation of the fitting accuracy of the reflector shape as well as the distribution and variation range of structure stress under sunshine are figured out. The results show that the temperature field under sunshine is quite non-uniform (the highest local temperature difference reaching 11°C), which significantly influences the fitting accuracy of the reflector shape, and would supply valuable references for FAST.