4m SiC主镜硬点定位机构指标性能分析

Performance analysis of hardpoint positioning mechanism for 4m SiC primary mirror

为了保证4 m SiC主镜的位姿精度和支撑系统的刚度,根据主镜支撑系统的光学指标对六杆硬点定位机构的相关参数指标进行了分析。应用有限元方法并借助于有限元软件,对六杆硬点定位机构进行了优化设计,确定了硬点分布半径、定位夹角、轴向刚度和轴向拉压力极限。分析计算出在主镜背部半径为1 345 mm的圆周上,均匀分布六个硬点机构连接点时,单个硬点轴向刚度达到15 000 N/mm。此时,主镜支撑系统的固有频率大于等于15 Hz,满足设计要求,为后续结构的优化设计提供了依据。

In order to ensure the position accuracy and the stiffness of the support system for the 4 m SiC primary mirror,the parameters of hardpoints in a hexapod configuration were analyzed according to the optical indexes of the primary mirror support system.Using the finite element method,the hardpoint positioning mechanism was optimized.The hardpoint distribution radius,positioning angle,axial stiffness and the limit of axial tension and compression were determined by the finite element software.The analysis results show that six hardpoints should be equally distributed at 1 345 mm of the radius on the circumference in the primary mirror backface.When the axial stiffness of the hardpoint reaches 15 000 N/mm,the natural frequency of the primary mirror support system is greater than or equal to 15 Hz.It can meet the design requirements and provide the basis for the following design optimization.