Simulation-Based Enhancement of Flexure Hinges Machining for the Ariel Telescope M1 Mirror

Abstract

The telescope main mirror (M1) of the Ariel Space Mission is a lightweight elliptical mirror with a parabolic surface, supported by three flexure hinges designed to mitigate deformation effects. Since these hinges must meet stringent planarity tolerances of 2 μm on their interface pads, they were manufactured using Single Point Diamond Turning (SPDT). However, initial manufacturing attempts failed in obtaining a component within the tolerance, revealing significant deformations of the flexure hinge during machining. This paper presents a simulation-based approach developed to address this issue. The component deformations were predicted considering the effects of centrifugal forces, gravity, and clamping. However, such simulation showed deformations significantly lower than the experimental results, suggesting unaccounted effects from coupling surface tolerances. Based on CMM measurements of the interfaces, a revised clamping configuration was proposed to minimize the influence of coupling tolerances. This approach significantly improved planarity, achieving a final flatness of 1.5 μm, well within the required tolerance. The proposed simulation-based procedure reduced trial-and-error iterations, improving manufacturing efficiency and precision in the production of the flexure hinges. Although not accounting for all factors, the simulations provided valuable insights into the causes of errors and guided the development of a successful fixturing strategy.