流体动压径向橡胶密封圈的密封特性研究

基于矩形断面密封圈这一简化模型，首次推导了具体的润滑方程和弹性变形方程，运用迭代算法计算了油膜厚度和油膜压力分布，并讨论了几个密封系统参数对油膜厚度的影响，对于得到预期的弹流润滑效果具有指导意义。     

高功率密度柴油机连杆大头轴承润滑特性分析

基于全局 Newton-Raphaon 方法和柔度矩阵法对高功率密度柴油机连杆大头轴承的润滑性能进行数值摸拟;耦合求解 Reynolds 方程和弹性变形方程,比较弹性变形的连杆大头轴承与刚性轴承的轴心轨迹与压力分布。结果表明：将全局 Newton-Raphaon 方法与柔度矩阵法结合起来,对高功率密度内燃机连杆大头轴承的弹流润滑进行分析,解决了轴承偏心率大于1时弹流润滑计算难于收敛的问题;考虑表面弹性变形的连杆大头轴承与刚性轴承相比,在最大气体爆发压力附近,油膜压力分布的形状和大小明显发生变化,特别是在轴承的两端处,油膜压力明显增加并接近轴承中间部分的压力。     

大型可倾瓦推力轴承弹流润滑问题的域外法解

介绍域外在处理弹流润滑问题是的应用，和边界元不相比，域外不需要对边界单元作繁琐的奇异积分处理，因而编程简捷，计算精确。作为算例，用域外法联立求解雷诺方程和弹性变形方程，计算了大型可倾瓦推力轴承的油膜压力、弹性变表和相应的特性参数。     

点接触弹流润滑条件下表面弹性变形研究

为研究弹流润滑条件下点接触表面变形及其对表面性能的影响,采用激光微织构法制备了一组不同形貌参数的滚动轴承滚道表面试件,基于表面频谱分析和弹流润滑快速算法（幅值缩减法）分析了试件在不同工况参数下的弹性变形。使用ISO 25178三维形貌参数体系对变形前后表面进行表征,研究了点接触弹流润滑状态下表面形貌的弹性变形与载荷、转速的关系。研究结果表明,弹流接触使表面形貌发生显著的弹性变形,载荷、转速等工况参数对变形量影响较大,表面弹性变形使得形貌参数发生显著变化。     

用柔度矩阵法对径向滑动轴承的弹流润滑分析

对径向滑动轴承进行了弹流润滑分析 ,利用了有限元软件MARC产生柔度矩阵 ,以近似计算轴承的弹性变形。对比分析了径向轴承的刚性流体润滑性能和弹性流体润滑性能。计算结果和已有文献资料良好吻合 ,表明在弹流润滑分析中用柔度矩阵法计算弹性变形具有良好的精度。     

弹性变形对径向轴承弹流润滑性能的影响

本文以上具有不同弹性模量、泊松系数的两种轴承材料为例分析了弹性变形对有限长径向滑动轴承的弹流润滑性能的影响。流体动力润滑方程采用雷诺方程,应用力学问题的通用有限元软件ＭＡＲＣ产生柔度矩阵计算弹性变形。对比分析了二种轴承的油膜压力分布、油膜厚度分布、最小油膜厚度以及承载能力。     

弹性箔片动压气体推力轴承承载性能研究

气弹耦合解是准确预测弹性箔片动压气体轴承承载性能的有效方法。通过引入箔片的弹性变形以及联立求解动压气体润滑Reynolds方程和弹性箔片的变形方程,给出了弹性箔片动压气体推力轴承的气弹耦合解。应用气弹耦合解理论,将顶层箔片的局部弹性变形纳入考虑范围,对弹性箔片动压气体推力轴承的承载性能进行了计算和分析。有限元数值仿真结果表明:顶层箔片在气膜压力作用下的局部弹性变形直接导致弹性箔片动压气体推力轴承承载能力的降低;根据轴承瓦块上气膜压力分布的特点合理设计支承拱箔的结构形式,可以减小顶层箔片的局部弹性变形,有效提高轴承的承载能力。得到了一种承载能力较高的弹性箔片动压气体推力轴承支承拱箔结构设计方案。     

径向滑动轴承弹流润滑耦合求解

提出了一种径向滑动轴承弹流润滑的耦合算法,该方法使用ANSYS软件中的APDL语言编写求解程序,采用差分法求解Reynolds方程,采用有限元方法求解弹性变形量,可以较快速准确地求解径向滑动轴承的弹流润滑问题。使用该算法对一特定参数的径向滑动轴承弹流润滑进行求解,获得油膜压力及厚度分布,验证了该方法的正确性。并进行了轴颈弹性变形量的计算,指出轴承两端轴颈与轴承座在工作时,间隙比较小,容易受磨粒磨损,理论上解释了轴颈两端磨损比中间较快的原因。     

考虑弹性变形的柱塞泵配流副温度特性研究

针对柱塞泵配流副的温度特性问题,建立了柱塞泵配流副的数学模型,在考虑弹性变形情况下,对柱塞泵配流副温度特性进行了研究.运用Fortran和MATLAB软件对数学模型进行了计算仿真,在油膜压力作用下,计算了配流副的弹性变形分布形态,得到了配流副的热弹流分布;对比了不同工况参数下的油膜温度最高值,分析得出了油膜的油液黏度、...     

弹性变形对锥形配流副润滑特性的影响

考虑到锥形配流副在高压条件下的弹性变形量已与油膜厚度同一数量级,应用弹性流体动力润滑理论,建立了其弹性变形条件下锥形配流副的润滑数学模型,采用有限差分法求解了模型的控制方程,进行了弹性变形对锥形配流副润滑特性的影响研究.结果表明,锥形配流副的弹性变形对其润滑特性有较大的影响,它增大了泄漏量,降低了摩擦转矩; 工作压力对摩擦转矩的影响程度要大于偏心率.     

A mixed elastohydrodynamic lubrication model with layered elastic theory for simulation of chemical mechanical polishing

Mixed elastohydrodynamic lubrication (mixed EHL) model has been successfully used to study phenomena in chemical mechanical polishing (CMP) process. However, in various mixed EHL simulation frameworks, a polishing pad's deformation cannot correctly be described by adopted models for pad deformation such as elastic half-space model and Winkler elastic foundation model. Thus, a more accurate model for pad deformation is needed, since this is the prerequisite for an accurate prediction of contact pressure and material removal rate, which is critical for improvement of polishing quality. In this paper, a layered elastic theory, which is frequently used to calculate flexible pavement response to truck loading, is introduced into the mixed EHL model. It is found that this theory has a similar accuracy to the traditional 3D finite element method for calculating the pad deformation. However, its computational cost is much lower, which is especially important for accurate and efficient simulation of mechanical behavior and material removal rate (MRR) in CMP. In order to highlight benefits of the proposed theory, simulations are carried out based on three different pad deformation models with the mixed EHL model. The pad deformation behavior is found to have a significant influence on the final simulation results, especially the MRR prediction. By comparing the different simulation models, the proposed layer elastic theory is found to be an optimal model for describing the polishing pad deformation behavior in CMP and can provide accurate simulation results on contact pressure distribution and the material removal rate.     

Aspects Regarding the Use of Probabilistic Models for Isothermal Full Film Rough Line Contacts

This article presents a method to improve the classical probabilistic EHL models by incorporating deterministic EHL results. We first provide a review of the latest developments in the probabilistic approach for the solution of a mixed EHL problem, as well as a review of the latest deterministic EHL results that can impact the probabilistic formulations. Next, we present a probabilistic algorithm for the computations of the load supported by the fluid, the elastically deformed asperities, and the plastically deformed asperities in a mixed EHL contact. The Chang-Etsion-Bogy elastoplastic micro contact model is used together with a corresponding probabilistic fluid flow model. We also present an approach in which the elastic roughness deformation induced by the oil film can be incorporated into the probabilistic model via the use of the amplitude reduction technique.     

圆弧齿轮点接触弹流基本模型的研究

从圆弧齿轮齿面微分几何分析、弹性接触变形和跑合磨损分析,建立了具有二维表面速度的点接触弹流基本模型。分析指出：圆弧齿轮点接触区域的形状和大小,由弹性接触变形和跑合磨损共同来确定比较合理;对齿面接触区压力分布进行插值计算并构造变形影响系数矩阵,可大大缩短弹性变形计算时间,并有足够的计算精度。     

A Theoretical Analysis of Mixed Lubrication by Macro Micro Approach: Part I—Results in a Gear Surface Contact

Mixed lubrication is a key to bring the performance analysis to the failure analysis in most tribological components. A macro-micro approach to mixed lubrication has been developed in the present model. The relation between the average contact pressure and the average gap for a typical rough contact patch is first determined numerically in micro scale. Using this relation, the average gap, average oil-film pressure, and average contact pressure in a mixed-lubricated elastohydrodynamic contact can be solved simultaneously in macro scale by treating the contact to be smooth. The total pressure is assumed a superposition of average asperity contact pressure and lubricant pressure. The new approach is simple, efficient and robust, and covers entire range of the load ratio, from unity (dry contact) to zero (full-film EHL). In addition, it can be used for a wide range of operating conditions and on a much larger contact area with a much less computing time than deterministic simulation of mixed lubrication. Implementation of the Fast Fourier Transform (FFT) allows for a rapid calculation of the elastic deformation and asperity con/act pressure. As a demonstration to this new approach, a parametric study of dimensionless speed, load and contact shape on the load ratio and gap ratio was conducted for a gear rough surface of the load ratio, from unity (dry contact) to zero (full-film EHL). In addition, it can be used for a wide range of operating conditions and on a much larger contact area with a much less computing time than deterministic simulation of mixed lubrication. Impletmentation of the Fast Fourier Transform (FFT) allows for a rapid calculation of the elastic deformation and asperity contact pressure. As a demonstration to this new approach, a parametric study of dimensionless speed, load and contact shape on the load ratio and gap ratio was conducted for a gear rough surface     

On the Dynamics of Lubricated Cylindrical Roller Bearings,Part I: Evaluation of Stiffness and Damping Characteristics

The stiffness and damping coefficients of a single roller-to-race contact of lubricated cylindrical roller bearings are numerically evaluated using a linearized perturbation method for both elastohydrodynamic lubrication (EHL) finite and infinite contact theories. A steady-state pressure equation is solved by a multilevel method and the elastic deformation is evaluated with the multilevel multi-integration method. Dynamic pressures are obtained by solving a set of perturbed pressure equations and are used to calculate the stiffness and damping coefficients. The influence of various nondimensional parameters (load parameter, speed parameter, material parameter, edge radius, and geometrical parameter) on the stiffness and damping are studied. The results show that a finite line contact gives higher values of stiffness and damping coefficients compared to an infinite contact, particularly at higher load and lower speed values. Based on the numerically evaluated data, curve-fitted relations for the stiffness and damping coefficients of a single roller-to-race contact are developed that can be used in the dynamic analysis of rotor–bearing systems.     

Some simple elastohydrodynamic lubrication deformation models

By assuming that the elastic deformation taking place in an elastohydrodynamic lubrication (EHL) contact can be described by a polynomial function, the corresponding pressure function can be determined by solving a linear integral equation. Some EHL models derived from applying this approach are described and briefly discussed.     

线接触弹流问题中可压缩性的影响

采用复合直接迭代法求解Reynolds方程,变形矩阵法求解表面变形,针对线接触弹流问题中压缩性的影响进行计算研究,讨论不同速度、不同负载条件下润滑剂可压缩性对压力和油膜厚度的影响。计算结果表明,可压缩性虽然对膜厚的影响相对小一些,但是对二次压力峰的位置与大小的影响很大;速度较高时,可压缩性是必须考虑的要素;考虑润滑剂可压缩性的影响,可以提高弹流润滑问题求解的稳定性。     

Effects of surface coating on elastohydrodynamic lubrication of line contacts

A numerical solution to the elastohydrodynamic lubrication (EHL) problem of two coated elastic bodies in line contact is introduced. The non‐Newtonian behavior of the lubricant is incorporated into EHL analysis using Eyring's nonlinear viscous model. The surface elastic deformations are computed from full elasticity analysis of layered elastic half‐space. The iterative Newton–Raphson technique is used in the numerical solution. Subsurface stresses are calculated using two different techniques, the numerical integral scheme based on Fourier transformation and the finite element method. The effects of surface coating (material and thickness) on the pressure profile and subsurface stresses are presented and discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

点接触弹流润滑问题的高效直接算法

在复合直接迭代法的基础上,运用分块迭代的思想将方程组降维,通过研究弹性变形影响因子对弹性变形的影响,将压力迭代矩阵由满元阵变为稀疏的带状阵,提出一种新的求解点接触弹流问题的高效直接迭代算法.与复合直接迭代法相比,该算法大大减少了计算量,计算效率至少提高20倍,并且可适用重载工况.将新算法计算结果与Hamrock-Dowson公式计算结果进行比较,并讨论迭代矩阵半带宽与收敛速度、载荷范围、计算精度以及数值稳定性的关系.结果表明,当压力迭代矩阵密度为满阵的22％～25％时,新算法具有最高的计算精度.     

时变等温线接触弹流润滑问题求解的多重网格技术

介绍了用多重网格技术求解时变等温线接触弹流润滑问题的方法,在算法上对压力迭代过程进行了简化;最底层网格上采用Ｎｅｗｔｏｎ－Ｒａｐｈｓｏｎ方法,在其它各层网格上使用Ｇａｕｓｓ－Ｓｅｉｄｅｌ低松驰迭代。作为算例,研究了脉冲载荷对弹流润滑特性的影响。