Topology and parametric optimization based lightweight design of a space reflective mirror

Abstract

For large space telescopes, the design of lightweight primary mirrors with an acceptable level of optical performance is a challenge. A parametric optimization method based on topology optimization of the basic configuration of the mirror is proposed. A finite-element model of the mirror is generated with linear shell elements, and the optimal distribution of the material is obtained using the continuum topology optimization technique. The lightweight ribs are grouped according to the results of topology optimization results. The design of experiment method is used to pick out the key factors for parametric optimization. The RMS value of the surface shape error of the mirror and the total mass of the mirror are treated as the objective merit functions, and the first-order natural frequency of the mirror is taken as a constraint for parametric optimization. Results show that the local stiffness of the mirror is significantly affected by the thicknesses of the ribs at the corresponding positions. The optimum mirror design obtained using our optimization method is compared with the initial design, and the comparison shows superior optical performance for the optimized mirror.