球铰支撑反射镜面形仿真分析

Simulation Analysis of Surface Figure for Optical Reflector with Ball Hinge Support

研究球铰支撑结构分析问题,球铰具有明显的接触和因相对滑动趋势而产生摩擦的特性,特性相比柔性铰链更为复杂,对其仿真也有一定的难处。传统的反射镜球铰支撑中比较常见的仿真方式是采用接触对方式,由于接触对仿真接触时局部网格细化程度高,导致计算耗时长,工程代价高。为此,提出了球铰支撑的有限元仿真研究。首先,对球铰支撑的柔性基理进行了理论分析,提出了三种有限元分析模型:节点耦合、MPC模拟转动和Gap单元模拟接触。三种模型的仿真分析结果表明:节点耦合模型仿真的刚性支撑,反射镜的面形PV值差,刚性支撑不能满足支撑要求;MPC和Gap单元均能够仿真球铰支撑,静摩擦系数对面形的影响不可忽略;与MPC方式相比较,Gap单元具有更高的分析精度。

Ball hinge has the characteristics of distinct contact and friction brought from relative glide trend. The characteristic of ball hinge support is more complex than that of a flexure hinge, and the simulation for ball hinge is more difficult. Currently, contact pair model is frequently used to simulate the optical reflector＇s ball hinge support while this simulation method needs a fine local grid refinement, leading to long computing time and high engineering cost. Therefore, the research of the finite element simulation for ball hinge support was carried out in this paper. The deformation of the ball hinge support was theoretically analyzed, and three kinds of finite element models were pro- posed, including the node - coupled model, multi - point - constraint （ MPC ） model and gap - element （Gap） mod- el. The simulation results of three models show that the surface accuracy of the node - coupled model is very poor, the MPC model and the Gap model can simulate the ball hinge, and the friction coefficient influences the surface fig- ure of the mirror in the gap model. The Gap model is more accurate than MPC model.