Passive accuracy adjustment of membrane reflectors

Based on the temperature changes in space, this paper presents an innovative method of passive accuracy adjustment for large membrane reflectors. Flexible patches with different coefficients of thermal expansion (CTEs) from that of the reflector material are pasted on to the reverse side of the membrane reflector. The patches and membrane reflector will experience different thermal deformation when the temperature changes in space, which allows surface accuracy adjustment. A finite-element analysis model of membrane reflector and patches is established and a static equilibrium equation of the membrane reflector system is derived. The paper also puts forward a thermal deformation influence coefficient matrix and proposes an optimisation model for surface accuracy adjustment. The coefficient of thermal expansion of each flexible patch is derived using a least-squares approach to optimise the objective function. The analysis of patch arrangement is discussed according to the surface accuracy influence coefficient matrix. The results of numerical examples under uniform temperature and a gradient temperature distribution show that passive adjustment of the surface accuracy of membrane reflectors is effective and the arrangement method of the flexible patches is feasible.