基于球轴承动刚度的轴系动态特性分析与优化

摘要

轴系动态特性受轴承刚度影响,而轴承刚度随轴系转速呈强非线性.因而研究轴系动态特性首先需要确定轴承刚度.首先使用球轴承受力分析的拟静力学模型,计算球轴承不同转速下的刚度,计算轴承刚度时,考虑了轴承内圈由于离心惯性力造成的变形的影响,使刚度计算值精确化;进而使用梁单元对轴系进行离散建立轴系的有限元模型,并求解了轴系的临界转速;并以临界转速为优化目标、对轴承跨距及轴内径进行了优化,提升了轴系的动态性能.文中研究内容以Matlab为基础进行编程实现.%The character of shaft systems is affected by stiffness of bearings, and the bearing stiffness is a high non-linear curve with rotation speed. Therefore, the stiffness of bearing is a precondition for dynamic character calculation of shaft systems. Firstly based on the quasi-static model, the dynamic stiffness with different rotational speed of a single ball bearing is calculated; the effect caused by centrifugal forces on inner ring is taken into consideration and the stiffness achieved is more accurate. Then the shaft system is modeled with finite element method using beam elements, and the critical speed calculation of shaft systems is carried out. Moreover, taking the bearing distance and inner diameter of the shaft as design variables and the critical speed as objective, a practical shaft system is optimized and the dynamic characteristics are improved consequently. The research work presented is implemented using Matlab.