Refined simulation of friction power loss in crank shaft slider bearings considering wear in the mixed lubrication regime

Friction reduction is a fundamental factor in decreasing fuel consumption of internal combustion engines. During the design stage of the engine the simulation of friction in the crank mechanism plays a vital role to develop optimum solutions. Due to the interaction of oil and elastic structures with rough surfaces in slider bearings, complex simulation models have to be used for representing the relevant physical behavior. The following article is focused on crank shaft slider bearings of large engines.The article describes a procedure evaluated by measurements showing how to model wear profiles of slider bearings to reach a high quality friction forecast. A fundamental influencing factor of bearing friction is given by the mixed lubrication regime and it is considered in the simulation model as part of asperity contact friction and hydrodynamic friction. Further effects result from the compliance in radial and width directions of the bearing structure and the wear of the bearing surface. Furthermore, the specific operating conditions of the slider bearing such as load, temperature, shaft speed and oil characteristics are essential and have to be taken into account.The objective of this investigation is to propose the wear profile of the bearing surface for the simulation model to be treated iteratively, where simulation results for the amount of mixed lubrication are successively assessed. For this purpose an iterative procedure is introduced and validated by measurements on a slider bearing test rig.The applied simulation method is based on elastic multi-body systems; the lubrication film contact is calculated based on Reynolds differential equation via the pressure balance calculated iteratively in the time domain. The model accounting for the mixed lubrication regime is based on the theory of Greenwood and Tripp.     

基于磨损试验的滚动轴承寿命及可靠性

笔者对特轻（1）系列36102滚动轴承进行了疲劳磨损试验。试验结果显示,磨损量与寿命呈线性关系。在给定可靠度为R=0．99情况下,该系列轴承可靠寿命的点估计x（R）=40723（次）。     

Comparison of the feedback source between shaft displacement and load variation in controlled bearings

There has been much research into improving the characteristics of an externally pressurized thrust bearing and this has used two methods: a flow control device and sensing mechanisms. This report uses the latter method and deals with an externally pressurized thrust gas bearing which has a variable flow control device controlled by two signals. One source of signal is shaft displacement and the other is load variation. The results predict that a bearing controlled by load variation has a much higher performance than that controlled by shaft displacement. In the experiment a bearing which feeds back load variation showed a high performance for shaft displacement over a wide range of frequencies.     

滚动轴承系统的寿命与可靠性

分析滚动轴承系统的寿命与可靠性之间的关系,对滚动轴承系统进行了可靠度的分配;对影响滚动轴承额定寿命的各因素进行讨论,并对滚动轴承额定寿命进行修正。     

大型船用螺旋桨悬挂式高精度静平衡机研究与实验

针对大型船用螺旋桨传统的平衡轴挂重法的弊端,介绍了一种适合大型船用螺旋桨的悬挂法立式静平衡检测方法,并且开发出了以静压球面轴承的油浮理论为基础和采用汽缸检测不平衡度的高精度平衡机.给出了该静平衡机的结构原理,研究了悬挂系统、定心系统、悬浮系统和控制系统的基本构成和工作方式,对静压球面轴承进行了受力分析,并且阐述了悬挂法立式静平衡机的工作过程.经过实验证明该新型静平衡机性能稳定、检测方便、检测精度高,完全达到大型船用螺旋桨的静平衡检测要求.     

Tribological performance of thin overlays for journal bearings

This paper describes the analysis of overlay materials used in journal bearings. We conducted model tests using ring-on-disc test configuration and component tests on bearing test rigs. Appropriate test strategies were designed for investigating the running-in, stable operating, emergency running and break-down behaviour. We investigated three different types of overlays: PbSn18Cu2 galvanic, polymeric overlay (PAI matrix with MoS₂-lamellae and graphite), PVD-coated AlSn20Cu-Sputter. Main results are: PbSn18Cu2 improves emergency running conditions. Polymeric overlay shows high need for running-in, where a particle structured surface is formed. AlSn20Cu-Sputter exhibits lowest wear and highest load capacity in component tests, but requires optimum running conditions.     

镀银膜轴承在油和脂润滑下的摩擦性能

试验研究镀银膜轴承在干摩擦、润滑油和润滑脂复合润滑下的摩擦性能。试验结果显示:在中低转速下,镀银膜轴承在银膜和液体润滑剂(油和脂)复合润滑下的摩擦因数仅相当于银膜干摩擦下摩擦因数的10%左右,且变化平稳;在高转速下,试验轴承在银膜和液体润滑剂复合润滑下的摩擦因数随转速增加而增加,且银膜与润滑脂复合润滑条件下的摩擦因数随转速增加得更快,但仍小于银膜干摩擦下的摩擦因数;镀银膜轴承在银膜和液体润滑剂(油和脂)的复合润滑下的磨损小于银膜干摩擦时的磨损;中低转速下,镀银膜轴承在液体润滑剂(油和脂)复合润滑下的摩擦磨损性能远优于银膜干摩擦时的摩擦磨损性能。     

阶梯轴承承载能力设计计算新方法

本文直接用流量方程对阶梯轴承的承载能力进行计算     

A finite element model for rolling contact fatigue of refurbished bearings

Bearing refurbishing has become a popular method of extending the life of rolling element bearings. In the refurbishing process the raceways of the bearing may be ground to remove any surface damage prior to repolishing and reassembly with larger sized rolling elements. In the current study a continuum damage mechanics finite element model was developed to quantify the damage in original and refurbished bearings. After calculating the damage accumulation for a set number of contact cycles with the original bearing geometry, refurbishing is simulated by removing a layer of the original surface. The refurbished microstructural model is then subjected to additional computational contact cycles until a fatigue crack reaches the surface, signifying failure. This model preserves the fatigue damage accumulated prior to refurbishing and evaluates its influence on the refurbished bearing fatigue life. All refurbished bearing surfaces showed a significant amount of life after refurbishing with L₁₀ lives from the point of refurbishment, varying from 20% to 94% of the original L₁₀ life. The results indicate that the remaining life of the refurbished bearing population is inversely related to the time before refurbishing and is proportional to the depth of the regrinding. Results obtained from this investigation are in good agreement when compared to the Lundberg-Palmgren bearing life equation modified for analyzing the life of a refurbished bearing.     

Design of elastomeric bearing system and analysis of it mechanical properties

This paper proposes a new type of bearing system. In this study, a method for design of on elastomeric bearing system and its mechanical property analysis are carried. Experimental and theoretical studies of the elastomeric bearings with fiber reinforcement were proved effective new lightweight bearing system. The fibers in the bearings for isolation are assumed to be flexible in extension, in contrast to the steel plates in the conventional bearing system. Several kinds of bearing systems in the form of long strips are designed, fabricated and tested. The results suggest that it is possible to produce the economical and effective fiber-reinforced elastomeric bearing that matches the behavior of a steel-reinforced bearing. Feasibility and advantages of the proposed bearings are illustrated by the application of the analytic procedure to the structure system. Results obtained here are reported to be an efficient approach with respect to bearing system and design of bearing against shock absorbing system when compared with other conventional one.     

基于最小油膜厚度的航空圆柱滚子轴承修正寿命研究

建立航空圆柱滚子轴承寿命计算的数学模型,比较ISO281:1990和ISO281:2007两种标准中关于滚动轴承寿命计算方法及修正系数的差异。针对航空轴承样本少、修正系数取值困难等问题,通过采用道森-希金森方程计算最小油膜厚度,确定滚动轴承的修正系数。通过某型直升机传动系统圆柱滚子轴承寿命的计算研究,验证了该方法的可行性。     

Tribological behavior of reciprocating friction drive system under lubricated contact

The dynamic friction and wear behaviors are investigated in reciprocating friction drive system using a 0.45% carbon steel pair. The effects of various operating parameters on the traction force, stick and slip time, and friction modes are examined under the lubricated contacts. Moreover, the critical operating conditions in classifying three friction modes are also established. Results show that the fluid friction induced by the shearing of lubricant dominates the variation of traction force and produces the positive slope γ at the first period of slip in the traction force–relative sliding velocity curve. The γ value decreases at higher driver speed during stick-slip motion due to the thicker fluid film and shear thinning effect. The γ value increases due to the asperity interactions as the friction region is transferred from stick-slip to sticking with normal load from 196 to 980 N. Furthermore, it is also found that the static friction force is independent of stick time for the tangential loading rate ranged from 1.12 to 16.8 s⁻¹. The transition region produces the severest wear under the different driver speeds, but the wear is insensitive to the friction regions and the severe wear only occurs at higher normal load due to the action of Hertzian contact.     

沉积温度及膜厚对离子镀银膜结构及摩擦学性能的影响

采用离子镀在不锈钢和45钢基体表面低温沉积银薄膜.利用X射线衍射仪(XRD)、扫描电镜(SEM)和真空摩擦试验机对低温沉积银膜的晶体结构、表面形貌和摩擦学性能进行了研究.结果表明:银膜的择优取向度随着沉积时间的延长和基体温度的降低具有明显变化;在-147℃沉积6 min条件下制备的银膜为表层具有(200)择优取向及底层为(111)择优取向的双层结构;银膜在载荷较高时也有较好的摩擦学性能.     

Design effects on the fretting wear behaviour of ball bearings

A change in design of a ball bearing is described based on the results of numerical and experimental analysis to reduce fretting wear. Increasing the radii of curvature of the inner and outer races by a small amount reduces the product of the relative slip δ and the tangential traction τ at the contact region, both of which are caused by Heathcote slip. This results in the consequent reduction in fretting wear because there is a good correlation between the amount of fretting wear and τδ. This prediction is confirmed experimentally by increasing the groove radius of the inner race from 4.02 to 4.21 mm for a ball of radius 3.97 mm.     

Lubricant film thickness variations in frictionless bearings

The possibilities are considered of diagnostics and monitoring of the technical state of frictionless bearings on the basis of the analysis of on-line recorded and processed oscillations of the lubricant film thickness. A possibility is shown of a significant increase in the monitoring efficiency when using the technique of automated processing of the diagnostic data received by using modern microprocessor means. Implementation of the proposed methodical approach will significantly shorten the duration of the frictionless bearing tests and will make it possible to govern the operating mode of the bearings in order to prolong their operation life.     

Film-forming mechanisms for self-lubricating radial spherical plain bearings with hybrid PTFE/aramid fabric liners modified by ultrasonic

PTFE/aramid woven fabric liners were modified by ultrasonic. With self-made wear tester, tribological properties of the self-lubricating radial spherical plain bearings with modified and unmodified liners over swivel times were investigated. With scanning electron microscope and energy disperse spectroscopy, the film-forming mechanisms were analyzed. Results show: ultrasonic modification can improve tribological performances of the liners. Through ultrasonic modification, continuous and stable PTFE transfer films which had better wear resistance formed in a shorter time. Bearings with modified liners occurred slight adhesive wear, while the bearings with unmodified liners occurred serious adhesive wear and abrasive wear during the test process.     

调心滚子轴承的摩擦学设计综述

从轴承的结构设计、滑动和摩擦、常见失效形式和摩擦学设计方面讨论了滚子的桶形设计、微观滑动与失效的联系,评述了轴承的系统设计、润滑膜厚计算、磨损寿命预测、摩擦学优化设计及其优化设计方法。     

PTFE/芳纶纤维编织衬垫自润滑关节轴承的黏接性能及摩擦学性能

对PTFE/Kevlar纤维混合编织衬垫分别进行超声波处理、稀土CeO2处理后,制备了自润滑关节轴承,利用Instron5944型电子万能材料试验机和自制的高频摆动摩擦磨损试验机对关节轴承进行了剥离强度测试和摩擦磨损性能试验,考察了前处理工艺对关节轴承的黏接性能和摩擦学性能的影响,并采用扫描电镜(SEM)观察分析了衬垫表面的微观形貌变化,以探究轴承的摩擦学性能与衬垫形成PTFE转移膜的成膜性能之间的关系。结果表明,衬垫经改性前处理后,不仅提高了衬垫与基体的黏接性能,而且提高了轴承的摩擦学性能;轴承的摩擦学性能与其在摩擦磨损过程中形成PTFE转移膜的成膜性能之间存在一定的对应关系,即PTFE转移膜的形成越快,耐磨性、均匀连续性越好,在摩擦磨损过程中表现出较优的摩擦诱导成膜性能,其摩擦学性能也越优。     

Life tests on elastomeric lip seals for pneumatic cylinders

A test method and a testing machine for evaluating the wear of lip seals for pneumatic cylinders are presented. The method and the machine have been evaluated with tests on different types of seals for cylinders with a 50 mm bore. Three levels of lubrication condition were examined: dry, with a film of grease, and with an optimum amount of grease. Differences were noted both between these conditions of lubrication, and between types of seal. © Leaf Coppin 1997.     

大型船用螺旋桨静平衡检测装置设计研究

分析了大型船用螺旋桨静平衡的检测现况,将球面静压轴承、电子称重法应用到螺旋桨静平衡检测装置,给出了螺旋桨偏心方位判定方法和静平衡检测的基本步骤,简化了测量过程,改变了以往静平衡采用的刚性支承方式,实现降低摩擦力,提高测量精度的目的.