空间相机碳纤维薄壁筒式主次镜支撑结构

Carbon fiber thin-walled cylindrical support structure between primary and secondary mirror in space camera

在大口径、长焦距空间遥感相机中,主、次镜间相对位置变化会影响相机的成像质量和稳定性,因此,作为主次镜间承力结构的主次镜支撑结构,是相机设计过程中的关键一环。本文针对大口径、长焦距相机特点,设计并研制了碳纤维薄壁筒式主次镜支撑结构。首先,根据给定光学系统,选取了筒式基结构形式。然后,根据筒式基结构形式的特点,依次对筒式结构的次镜支撑梁和纵向加强筋的几何结构形式进行了分析与选型。接着,为了充分发挥碳纤维材料铺层可设计性特点,对主次镜支撑结构进行了结构关键尺寸、铺层厚度和铺层角度三者的迭代优化设计,并对设计结果进行了有限元仿真分析。最后,通过测量次镜角度变化量和特征级扫频振动试验,验证了支撑结构的稳定性和结构刚度。试验结果表明:次镜相同状态下长期监测差值变化量小于1.5″,重力翻转前后变化量小于1.08″,支撑结构一阶固有频率大于115 Hz,轴向频率大于180 Hz,表明主次镜支撑结构具有良好的刚度和结构稳定性,满足设计指标要求。

In large-aperture and long-focus space remote sensing cameras,the relative position changes between the primary and secondary mirrors affect the imaging quality and stability of the camera. The support structure between the primary and secondary mirrors,that is the bearing structure between them,is integral for the camera design process. In this study,a carbon fiber thin-walled cylindrical support structure between the primary and secondary mirrors was designed,based on the characteristics of large-aperture and long-focus cameras. First,the cylindrical base structure was selected depending on the optical system considered. Then,based on the characteristics of the cylindrical base structure,the geometric structure of the secondary mirror support beam and the longitudinal reinforcement ribs of the cylindrical structure were analyzed and selected in sequence. Subsequently,to fully utilize the design characteristics of the carbon fiber material layup,the iterative design optimization of the key size of the support structure,thickness of the layup,and angle of the layup was performed,and the design results were analyzed by conducting finite element simulations. Finally,the stability and structural rigidity of the support structure were verified by measuring the change in the angle of the secondary mirror and conducting the characteristic-level sweep frequency vibration test. The results indicated that the differences in long-term monitoring under the same conditions for the secondary mirror was less than 1. 5 ",change before and after gravity flipping was less than 1. 08",first-order natural frequency of the supporting structure was greater than 115 Hz,and axial frequency was greater than 180 Hz. Thus,the support structure between the primary and secondary mirrors exhibited excellent rigidity and structural stability,satisfying the requirements of the design index.