根据传统同轴反射式次镜支撑结构特点, 建立了以传统次镜支撑结构外包络为基础的次镜支撑待优化模型, 并采用变密度拓扑优化方法对该模型进行优化设计.根据拓扑优化结果设计了遮拦比为0.085的同轴反射式次镜支撑结构.有限元仿真结果表明: 在结构遮拦比、质量相同的情况下, 优化后同轴反射式次镜支撑结构的结构基频和结构刚度相较于传统三翼和四翼结构均有显著提高.加工了优化后的次镜支撑结构, 并进行了随机振动试验.试验结果表明: 优化后的次镜支撑结构基频为470 Hz, 与有限元仿真结果477 Hz的相对误差在2%以内, 验证了有限元计算模型的可靠性和真实性.该次镜支撑结构适用于需要较低遮拦比和较高刚度的同轴反射式光学系统中.

A sub-mirror support optimization model based on the outer envelope of the traditional secondary mirror support structure was established, according to the characteristics of the traditional coaxial reflective secondary mirror support structure. The variable density topology optimization method was used to optimize the model. According to the topology optimization results, a coaxial reflective secondary mirror support structure with an occlusion ratio of 0.085 was designed. The finite element simulation results show that the basic frequency and structural stiffness of the coaxial reflective secondary mirror support structure are significantly improved compared with the traditional three-wing and four-wing structures in the case of the same structure shielding ratio and mass. The optimized secondary mirror support structure was processed and a random vibration test was conducted. The test results show that the optimized basic frequency of the secondary mirror support structure is 470 Hz, the finite element simulation result is 477 Hz, and the relative error is within 2%, which verifies the reliability and authenticity of the finite element calculation model. The secondary mirror support structure is suitable for use in a coaxial reflective optical system that requires a lower mask ratio and higher stiffness.