非牛顿流体润滑轴承—转子系统非线性动力学分析

发布时间：2018-05-14 00:44

本文选题：轴承-转子系统 + 非线性液膜力　；参考：《天津大学》2012年硕士论文

【摘要】：随着科学技术的不断进步,高速高精密机床作为一个国家科学技术进步的标志,越来越多的受到各个国家的关注。对于高速高精密机床不仅要求机床主轴能够保证稳定的高速运转,而且要保证极小的跳动和回转误差。考虑到主轴高速运转时的各种非线性因素,如非线性液膜力、气流力、密封力等,对主轴系统进行非线性动力学分析是必不可少的。机床主轴系统可归结为一类轴承-转子系统。上述因素中以非线性液膜力的影响最为突出,因此有必要研究非线性液膜力作用下的轴承-转子系统非线性动力学行为。实际应用中,人们会在润滑剂中添加一些添加剂来改善润滑特性,而此时的润滑剂就不能再简单的看作是牛顿流体,而应当以非牛顿流体来研究。目前,对轴承-转子系统非线性动力学特性的研究多局限于牛顿流体润滑,而对于非牛顿流体润滑的轴承-转子系统非线性动力学特性的研究较少。本文应用非线性动力学的基本理论和研究方法,研究了非线性支撑情况下的偶应力流体润滑轴承-转子系统非线性动力学特性。论文工作主要分以下几个方面: 1.对高精密机床主轴的研究进展,水润滑技术研究现状,偶应力流体研究现状及非线性动力系统的相关概念与常用的研究方法等进行综述; 2.推导出偶应力流体润滑情况下的液膜力模型,并在此基础上建立了非线性支撑情况下的轴承-转子系统运动微分方程。 3.利用数值方法求出系统在不同参数情况下的分岔图、时间历程图、相图、Poincare映射图、频谱图等特征图形。结果表明,非线性支撑能够更好地抑制系统分岔失稳;偶应力流体的分子特征长度对于系统动力学特性具有显著的影响,随着分子特征长度的增大系统临界转速变小,振动幅值也随之变小。 4.分析了润滑剂粘度、半径间隙和主轴刚度对于系统动力学特性的影响。结果表明,润滑剂粘度、半径间隙和主轴刚度对系统动力学都有着明显的影响。通过本文的研究,对偶应力流体润滑情况下的轴承-转子系统的非线性动力学特性有了一定的认识,研究结果为主轴系统的设计提供了一定的依据。
[Abstract]:With the development of science and technology, high-speed and high-precision machine tools, as a symbol of the progress of science and technology in a country, are paid more and more attention by various countries. For high speed and high precision machine tool, not only the spindle of machine tool can be guaranteed to run at high speed, but also the minimum runout and rotation error should be guaranteed. Considering all kinds of nonlinear factors, such as nonlinear liquid membrane force, airflow force and sealing force, it is necessary to analyze the nonlinear dynamics of the spindle system at high speed. Machine tool spindle system can be reduced to a kind of bearing-rotor system. Among the above factors, the nonlinear liquid membrane force is the most important factor, so it is necessary to study the nonlinear dynamic behavior of the bearing-rotor system under the nonlinear liquid membrane force. In practical application, some additives will be added to the lubricant to improve the lubricating properties. However, the lubricant can no longer be regarded as a Newtonian fluid, but should be studied with a non-Newtonian fluid. At present, the research on the nonlinear dynamic characteristics of bearing-rotor system is limited to Newtonian fluid lubrication, but the study of non-Newtonian fluid lubrication of bearing-rotor system nonlinear dynamic characteristics is less. In this paper, the nonlinear dynamic characteristics of the bearing-rotor system under the condition of nonlinear support are studied by using the basic theory and research method of nonlinear dynamics. The work of the thesis is divided into the following aspects: 1. The research progress of high precision machine tool spindle, the research status of water lubrication technology, the research status of couple stress fluid, the related concepts and common research methods of nonlinear dynamic system are summarized. 2. The liquid film force model under the condition of couple stress fluid lubrication is derived, and the differential equation of motion of the bearing-rotor system under the condition of nonlinear support is established. 3. The bifurcation diagram, time history diagram, phase diagram Poincare map and spectrum diagram of the system under different parameters are obtained by numerical method. The results show that the nonlinear bracing can better restrain the bifurcation instability of the system, and the molecular characteristic length of the coupling stress fluid has a significant effect on the dynamic characteristics of the system, and the critical speed of the system becomes smaller with the increase of the molecular characteristic length. The vibration amplitude also becomes smaller. 4. The effects of lubricant viscosity, radius clearance and spindle stiffness on the dynamic characteristics of the system were analyzed. The results show that the viscosity of lubricant, radius clearance and spindle stiffness have obvious effects on system dynamics. Through the research in this paper, the nonlinear dynamic characteristics of the bearing-rotor system under the condition of dual stress fluid lubrication have been recognized to a certain extent, and the research results have provided a certain basis for the design of the spindle system.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH113

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