Experimental Investigation of Thermal and Hydrodynamic Effects on Radially Grooved Thrust Washer Bearings

In this study, an experimental investigation on the effects of grooves on thrust washer bearings is investigated. Eight equally sized grooves are machined about 100 μ m deep into one side of a flat-faced steel washer. This thrust washer bearing is located between a helical gear and its carrier and is tested on a test rig capable of measuring frictional torque and the temperature of the bearing at different speeds. It is found that the grooved washers had lower bearing temperatures and failed at significantly higher loads than the control washer with no grooves. For a test procedure with varying operating conditions, the coefficient of friction is also significantly lower for the grooved washers. However, the grooved washers had about the same coefficient of friction as the control washers at each step when the speeds are very high. The results from various tests suggest that the increased amount of lubricant passing through the grooved surface of the washer removes heat from the washer bearing by convection. This decrease in stored heat conducted from friction deters thermoelastic instabilities and the reduction of hydrodynamic stiffness due to the decrease in viscosity. Enhanced hydrodynamic load-carrying capacity is also evident in the grooved washers test results.     

基于 ABAQUS 的角接触球轴承动力学仿真分析

为研究角接触球轴承在不同转速下温度及位移变化,基于 Palmgren 摩擦生热理论,综合考虑轴向载荷、切向摩擦和法向摩擦等边界条件,在 ABAQUS 软件中建立了轴承完全热力耦合模型。对轴承外圈施加固定的轴向载荷,并对内圈加载不同的转速,使用显示求解器求解轴承在不同转速下各部件温度和轴承内圈位移变化。仿真分析表明,该模型能够准确地反映轴承的温升以及轴承内圈位移情况,为轴承选取合适工作转速区间提供理论支撑。     

Experimental Analysis of the Wear,Life and Behavior of PTFE Coated Thrust Washer Bearings Under Non-Axisymmetric Loading

In this work the behavior and life of a PTFE coating on a flat thrust washer bearing is investigated. The thrust washer bearing is located between a helical gear and its carrier, and is subjected to non-axisymmetric loading and wear. The volume of worn material is approximated by measuring the difference in height between the worn and unworn surfaces. It was also found that the surface roughness of tested washers increases with the severity of wear, in most cases. After a finite number of cycles the effective coefficient of friction between the surfaces increases, suggesting that the coating is wearing off and losing effectiveness. The rate at which the coating wears off also varies with load and speed, hence, there is a region of operation that minimizes the wear and friction.     

基于虚拟仪器的滑动轴承摩擦试验系统的设计

通过改造MS-800A四球摩擦试验机的摩擦实验部分,引入虚拟仪器LabVIEW软件建立测试系统,对摩擦副之间摩擦系数和温度的变化进行采集、处理和实时检测,建立对滑动轴承的摩擦磨损试验系统,从而建立一套研究滑动轴承在不同工况条件（润滑介质、载荷和转速）下的摩擦磨损特性。     

进水温度对水润滑轴承润滑特性的影响

为研究进水温度变化对水润滑轴承润滑特性的影响,采用有限差分法建立水润滑轴承弹流润滑模型,分析不同进水温度和载荷条件下水润滑轴承润滑特性的差异,并且通过试验验证摩擦因数的变化规律。研究发现：随着进水温度升高,轴承的水膜压力下降,但在水膜压力峰区域最大水膜压力升高、最小水膜厚度减小、偏心率增大,表明进水温度升高对润滑性能有着负面影响;在相同的载荷和转速下,轴承摩擦因数随着进水温度升高而下降,且高载荷下进水温度对摩擦因数的影响更大。通过试验发现进水温度越高对摩擦因数变化的影响越大,不同进水温度下载荷越低,载荷的变化对摩擦因数变化量的影响越大。     

An experimental investigation of wear and fatigue life reduction of boundary lubricated spherical roller thrust bearings

Wear and fatigue life reduction in boundary lubricated spherical roller thrust bearings has been investigated. Previously presented results from measurements show that there is a significant change in the washer profile due to wear. This change in surface profile greatly affects the fatigue-life of the bearings. A fractional factor experiment series was used to study how the contacting surfaces of the bearing were affected by the rotational speed, load, hardness of the contacting surfaces and type of oil. The results show that the fatigue life and amount of wear on the washer surfaces were affected by the type of lubricant and rotational speed. A change of the load or a change of the hardness of the contacting surfaces did not influence the wear or the fatigue life of the contacting surfaces.     

Flow Visualization in a Pocketed Thrust Washer

The objectives of this study were to experimentally and numerically investigate oil flow in surface-pocketed thrust washers. In order to achieve the experimental aspects of this investigation, a thrust washer test rig was designed and developed to visualize the lubricant flow at the contact interface. A novel approach for creating the pockets was developed to allow optical inspection of the lubricant during thrust washer operation. The thrust washers were fabricated using a glass disk with a thin layer of steel shim stock adhered to the surface. The micrometer-thick shim stock was machined using an Nd:YAG laser to create the circular pocket geometries and then glued to the glass disk. A mirror and camera were placed below the semitransparent washer to observe the lubricant flow in the pocket. The results obtained from this configuration illustrate a cavitation bubble forming on the leading edge of the pocket followed by a sharp transition back to liquid. The size of the cavitation area was found to be a function of rotational speed, nominal bearing pressure (NBP), viscosity, and pocket geometry. The cavitation area ratio (gaseous region divided by the pocket area) increased for greater speeds and higher viscosities and decreased for larger pocket diameters, deeper pockets, and higher NBPs. The friction force for various thrust washer designs was also measured as a function of load, speed, and lubricant. The results showed that shallower, wider pockets provided the lowest friction. It was found that, generally, the conditions that minimize friction also result in a stable cavitation region. ANSYS Fluent computational fluid dynamics software was used to develop a three-dimensional model of the pocketed thrust washer utilizing the full Navier-Stokes equations to investigate the cavitation and pressure distribution occurring at the contact and corroborate the experimental results.     

UHMWPE基水润滑轴承摩擦及润滑特性的试验研究

针对纤维填料改性UHMWPE水润滑轴承的摩擦磨损性能进行研究。在平面摩擦磨损试验机上对玻璃纤维及碳纤维填料对UHMWPE复合材料摩擦性能进行试验,并分析GF-CF-UHMWPE材料与Thordon SXL材料在干摩擦、水润滑工况下的摩擦因数及磨损量。最后,采用径向水润滑轴承试验台对比研究了GF-CF-UHMWPE轴承和Thordon SXL轴承在不同载荷下摩擦因数随转速的变化规律。结果表明:纤维填料能显著增强UHMWPE的减摩性和耐磨性,GF-CF-UHMWPE材料具有更好的耐温性能,线性热膨胀系数也显著减小;GF-CF-UHMWPE轴承具有相同载荷下启动转速低,启动摩擦因数小的特性。     

陶瓷球轴承的热弹流润滑分析

建立陶瓷球轴承热弹流润滑的数学模型,利用多重网格法和逐列扫描法,得到陶瓷球轴承的点接触热弹性流体动力润滑完全数值解,并与普通轴承计算结果进行比较。结果表明:转速与载荷会对陶瓷轴承的接触区的压力、膜厚、温度产生影响,其中随着转速的增加,最小膜厚增加,摩擦因数减小,滚动体表面温度下降,而随着载荷的增加,最小膜厚减小,摩擦因数增大,滚动体表面温度上升;在相同的工况参数下,陶瓷球轴承的油膜压力低于普通轴承,膜厚高于普通轴承,轴承内圈、滚动体、中层油膜的温升小于钢质轴承,因而陶瓷轴承的润滑性能更好,使用寿命更长。     

一种新型摩擦材料在水润滑下的摩擦学性能研究

采用环块式摩擦磨损实验研究了一种新型摩擦材料在水润滑状态下不同载荷与转速对试样摩擦学性能的影响,并对比干摩擦条件下的摩擦学性能变化,借助磨损表面形貌观察分析其磨损机理。实验结果表明:水润滑条件下,摩擦系数随着载荷的增大而减小,随着转速的提高先增加后减小;磨损率随着载荷与转速的提高都减小。相同载荷与转速下,干摩擦时磨损机理以磨粒磨损和黏着磨损为主,而水润滑条件下水形成边界润滑,磨损机理以磨粒磨损和轻微的黏着磨损为主;水润滑条件下摩擦系数和磨损率均低于干摩擦,主要是由于水起到了润滑和冷却的作用,阻止了转移膜的形成,并在材料表面形成水膜起到了边界润滑的作用。     

GCr15及G20CrNi2Mo轴承钢高温润滑条件下摩擦磨损性能

为了探究轴承钢在高温润滑条件下的摩擦磨损性能,采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、洛氏硬度计等对GCr15高碳轴承钢和G20CrNi2Mo渗碳轴承钢组织、物相及硬度进行了表征,利用QG-700型气氛高温摩擦磨损试验机研究轴承钢材料不同条件下的高温润滑摩擦磨损性能,并分析其磨损机制.结果表明:2种轴承钢...     

Effect of surface roughness on the hydrodynamic lubrication of porous step-slider bearings with couple stress fluids

This paper presents the theoretical study of the effect of surface roughness on the hydrodynamic lubrication of porous step-slider bearings. A more general form of surface roughness is mathematically modeled by a stochastic random variable with non-zero mean, variance and skewness. The generalized average Reynolds-type equation is derived for the rough porous step-slider bearing lubricated with Stokes couple stress fluid. The closed-form expressions for the mean load carrying capacity, frictional force and the coefficient of friction are obtained. The performance of the rough porous step-slider bearing is compared with a corresponding smooth porous step-slider bearing. The numerical computations of the results show that the negatively skewed surface roughness pattern increases the load carrying capacity and decreases the coefficient of friction whereas the adverse effects were found for the positively skewed surface roughness pattern.     

橡塑双层复合材料水润滑轴承流固耦合分析

橡塑双层复合材料水润滑轴承综合了橡胶阻尼性好和塑料摩擦性能好的特点，是一种极具发展潜力的新型水润滑轴承，然而其润滑承载机制尚不明确。采用流固耦合仿真方法研究该种轴承在不同载荷、轴瓦厚度和弹性模量下的轴瓦变形分布特点和规律。结果表明：轴瓦变形主要发生在橡胶层，橡胶层轴瓦变形影响塑料层轴瓦的形状，并使其整体发生移动；随载荷增大，轴瓦变形量增大，轴瓦刚度系数减小；随塑料层轴瓦厚度增大，轴瓦总变形量近似线性减小，轴瓦刚度系数增大；而塑料层轴瓦弹性模量的变化对轴瓦总变形和刚度系数影响相对较小。     

Effect of surface coating and tin plating on friction characteristics of P-110 tubing for different thread compounds

Design factor problems related to galling failure have become an increasing concern for deepwater offshore wells. This paper presents the results of an experimental study conducted to determine friction characteristics of P-110 tubing coated with manganese phosphate and plated with tin. Six repeated tests were run to investigate the effect of lubrication type on friction characteristics of P-110 tubing by using thread compounds of API modified Threadkote-706, Shell Type-3 and Graphite/PTFE at a rotational speed of 5 rpm. In each test the bearing load was increased monotonically to a maximum value of 625 kN. The results of this study clearly indicate the importance of tin-plating in reducing the coefficient of friction.     

焊接工艺参数对FGH96合金惯性摩擦焊过程材料塑性流动行为的影响

采用数值模拟方法对FGH96合金惯性摩擦焊过程进行分析,获得温度、轴向缩短量、材料流动与飞边四者之间的关系,着重研究初始转速与轴向压力等焊接工艺参数对材料塑性流动行为的影响规律。研究结果表明:在惯性摩擦焊初始阶段,材料温度与流动速度较低,无飞边产生;随着焊接过程的进行,材料的温度与流动速度呈现先升高后降低的规律;在焊接过程进入稳态后,摩擦面中心区域的材料主要沿试件的旋转方向流动,而摩擦面上两边界附近的材料向面外流动并形成飞边,飞边尺寸与弯曲程度随焊接时间的增加而增加。同时,随到摩擦面距离的增加,材料的流动速度逐渐降低且材料沿轴向流动的速度分量增大。结合FGH96合金惯性摩擦焊轴向缩短量的数值模拟结果,解释了从提高材料流动速度的幅度上看增加轴向压力优于初始转速的原因。     

轴表面DLC涂层对滑动轴承润滑承载性能的影响*

为研究轴表面类金刚石(DLC)涂层对滑动轴承承载性能的影响,利用滑动轴承实验台测试轴线对中及倾斜工况下灰铸铁、铝合金和聚酰亚胺(PI)涂层轴承分别与40Cr钢轴和DLC涂层轴配合时的轴心轨迹和极限载荷,并测试3种材料与40Cr钢和DLC涂层的摩擦因数。结果表明:相较与40Cr钢配合,灰铸铁和铝合金与DLC涂层配合时摩擦因数减小,重载下轴承偏心率减小,轴线对中工况下灰铸铁轴承的极限载荷超过10 MPa,铝合金轴承的极限载荷增大到7.8 MPa(增大1.1倍),轴线倾斜工况下轴承抱死失效时边缘变形增大;但重载下PI涂层与DLC涂层配合时摩擦因数增大,轴线对中工况下轴承极限载荷减小至3.6 MPa(减小44%),轴线倾斜工况下轴承抱死失效时边缘变形减小。     

Hydrodynamic Pressure Generation in a Pocketed Thrust Washer

The objective of this study was to experimentally investigate hydrodynamic pressure generation in surface-pocketed thrust washers. A novel method of pressure mapping was developed to allow for in situ measurement of the pressure generated by surface modifications. Thin-film pressure transducers, located just below the thrust washer surface, were used to measure pressure variations as a function of the operating conditions. Contour maps showing the cavitation region and the location of peak pressure were clearly displayed. The experimental work presented maps the pressure profiles with real-time, high-resolution sensors. The thin-film pressure transducers were used to investigate the pressure interactions between surface features. In addition to the experimental setup, a model of the contact was developed using ANSYS FLUENT. Cavitation, friction, film thickness, and load support were all compared with experimental results and the two were shown to be in good agreement. The model demonstrated an accurate prediction of the pressure profile but varied slightly with the predicted load support of the thrust washer. The simulation was then used to optimize the pocket density for the experimental operating conditions. The optimal bearing design had the highest load-carrying capacity with a low friction coefficient.     

磁动压混合推力轴承的研究

提出了一种利用磁场力辅助流体动压轴承工作的磁动压混合推力轴承。这种轴承在机器起动和停车阶段，依靠磁场力支承转子系统，当机器达到一定转速后，主要由动压油膜承受轴上载荷，从而克服了流体动压轴承在此阶段出现混合摩擦的问题。研究了这种混合推力轴承承载能力的数学模型，计算了磁轴承的承载能力。设计制造了试验装置并对这种轴承在不同气隙和转速下的性能进行了试验测试。结果表明这种磁动压混合的工作原理是可行的，可以改善流体动压轴承的工作性能。     

Simulation of a nonstationary contact in a sliding bearing with allowance for frictional heating and convective heat transfer

The serviceability of polymer dry sliding bearings is governed by a number of parameters, such as the rotational velocity of the shaft, the friction coefficient, еру thermal and mechanical properties of bearing members, and hence, the resulting contact temperatures. This work was aimed at developing a calculation model of the operation of a two-layer polymer dry sliding bearing, determining the temperatures distributions and the equivalent and contact stresses in bearing members, and choosing the optimum parameters of the bearing system for which heat balance is achieved.     

采用螺旋槽锥轴承的飞轮储能系统空载损耗研究

计算了锥面螺旋槽轴承的摩擦损耗和储能飞轮电机铁损功率,分析了轴承锥顶半径和轴向承载力对轴承摩擦功耗的影响,计算与试验均表明:适当减小锥顶半径、降低螺旋槽轴承承载力可以有效减小轴承摩擦损耗。在多个转速下测定了不同锥顶半径螺旋槽轴承支撑的飞轮储能试验系统的空载损耗功率,测试结果与理论预计一致。计算表明,现有铁芯电机的铁损较大。