空间环境回转-直线往复复合运动密珠轴系力载特性分析

Analysis of Load Characteristics in Linear Bearing with Shaft Used in Space Environment for Rotary-linear Motion

空间机构需要实现回转与直线往复的复合运动功能,在真空、大温差等空间环境下的大间隙密珠轴系内部弯矩载荷与转矩载荷的施加顺序和载荷与间隙协调关系对轴系接触状态和润滑可靠性产生重要影响。针对环境工况参数建立空间轴系及其各组成轴承单元工作时的内部接触载荷与间隙数学模型,通过力载与变形协调关系联立平衡方程组,采用阻尼牛顿迭代法获得全轴系的应力与变形解。由分析计算可知,外部载荷的施加顺序和环境温度引起轴系内部各轴承间隙改变,最终影响其内部接触状态。结果表明,当轴承内部间隙在外载荷作用下消除后,不同的载荷施加顺序对轴系的力载分布状态和轴承内部接触应力的影响很大:轴系先承受扭矩载荷后承受径向力状态下的内部最大接触应力水平远大于先承受径向力后承受扭矩载荷,相应增加比例约60%。分析模型可针对航天工程领域环境与工况因素影响下空间轴系的力载特性进行摩擦学分析与设计。

The space devices with a function of rotary-linear motion are usually used in an environment of alternating temperature and high vacuum. Because of the clearances between linear bearings and shaft are large and have coordinated relationship with external loads, while the internal contact situation and lubricating reliability will be considerably influenced by the sequence of load applied with torsion and torque. According to the parameters of environment and load conditions, the mathematical models of internal contact situation and gaps are deduced for the whole shaft and every bearing. Using the damping Newton method, the equilibrium equations of load and deformation are solved, and that the contact stresses and deformations of the whole shaft are gained. From the analysis and calculation, the internal contact situation vary according to the bearing clearances which influenced by the sequence of load applied and the environment temperature. The results show that, the internal load distributions and contact stresses in the bearings are determined significantly by different sequence of load applied on the shaft： When applied the radial load first and then the torque, the maximum stresses inside the bearings will increased about 60 percent than those of the reversed sequence loads. This method could be used for space devices tribological analysis and design in the aerospace engineering field.