Simultaneous stiffness enhancement and mass reduction in airborne optical systems via topology optimization

Stiffness enhancement and lightweight design of optical systems play a crucial role in advancing the application of optical systems in aerospace. Conventional lightweight design approaches employ experience-driven methodologies utilizing biomimetic templates, necessitating iterative refinement cycles that compromise design efficiency. Existing topology optimization methods suffer from unclear topology, slow convergence, and nonmonotonic objective functions when solving the structural optimization problem for design-related loads. We propose the exponential approximation of material properties as a penalty function to reduce the gray units and a sensitivity suppression algorithm to solve the nonmonotonic problem of the objective function. Meanwhile, existing topology optimization methods also exhibit significant mesh generation challenges for geometrically intricate three-dimensional structures. We call commercial finite element software to deal with the meshing problem of complex 3D structures and realize the data interaction between topology optimization algorithms and commercial finite element software. This method improves the stiffness of the optical system while achieving lightweighting, reducing the mass of the mirror and frame in the optical system by 28.7% and 16.1%, and the deformation by 53.4% and 12.9%, under 90 deg working condition. Our proposed methods are general and instructive in guiding the optimization of the topology of complex 3D structures under design-dependent loads.