渐开线重载齿轮传动非牛顿流体热弹流润滑分析

建立渐开线重载齿轮传动的非牛顿流体热弹流润滑模型,分别采用多重网格法、多重网格积分法、逐列扫描法计算齿面压力分布、油膜厚度和齿面温度,分析润滑油黏度和齿轮转速对重载齿轮传动接触疲劳寿命的综合影响。结果表明:在润滑油黏度和齿面综合速度乘积固定不变的前提下,同时改变其中任一量对轮齿接触应力没有影响。     

润滑油环境粘度对非稳态热弹流润滑的影响

分析了不同的环境粘度对非稳态热弹流润滑的影响。指出了摩擦因数不是单调地随环境粘度的变化而变化,在一定工况下,会存在一个最优的环境粘度。粘度的变化对膜厚的影响大于对压力的影响,使用粘度系数高的润滑油,会形成较高的第二压力峰和较大的表面摩擦力,对接触疲劳寿命有不利影响。     

基于弹性流体动力润滑理论的齿轮设计

齿轮传动是重要的传动形式之一,良好润滑是保证齿轮正常传动的关键因素.根据所建立的齿轮弹性流体动力润滑数学模型,进行数值求解,分析载荷参数、润滑油粘度对齿轮弹流润滑性能的影响规律.结果表明随着载荷增加,二次压力峰值减少,位置向入口区偏离;而增大齿轮润滑油的粘度,弹流油膜压力影响不是很大,油膜膜厚是逐渐增加的.最后,根据齿轮形成的最小油膜厚度与齿面粗糙度之比(即膜厚比)分析了齿轮传动的润滑状态.     

探究不同黏度的润滑油对齿轮疲劳寿命的影响

通过油液分析技术探讨了不同黏度的润滑油对齿轮齿面耐磨性的影响。首先在Romax软件中仿真分析了不同黏度的润滑油对齿面间油膜厚度的影响,然后通过齿轮疲劳运转试验分析了不同黏度的润滑油对齿面磨损的影响。通过对油液进行分析监测,并结合仿真计算的油膜厚度、油液浓度分析数据和最终齿轮寿命结果可知,一般混合润滑状态下,润滑油黏度、油膜厚度、疲劳剥落颗粒物浓度和齿轮寿命有一定的关系,随着润滑油黏度升高,齿面的磨损状态得到改善,齿面应力更加均匀,齿轮寿命得以延长。     

不同工况条件对直齿轮副弹流润滑特性的影响研究

根据弹流润滑理论与渐开线直齿轮齿廓啮合特点,建立非牛顿流体直齿轮副弹流润滑模型,采用数值方法求解不同工况条件对油膜压力、油膜厚度分布及啮合周期内摩擦因数的影响。研究表明,转速、输入转矩及润滑油粘度产生变化,均会影响油膜压力及膜厚分布,最终导致啮合周期内摩擦因数发生变化,且摩擦因数在靠近节点处达到最小值。     

某型直升机行星齿轮机构弹流润滑研究

分析了某型直升机主减速器行星齿轮机构弹流润滑工况,研究了该齿轮系弹性润滑最薄弱啮合部位,计算得出了行星齿轮传动机构中齿宽、齿轮模数和压力角等齿轮参数对弹性润滑油膜厚度的影响,提出了改进直升机主减速器行星齿轮机械润滑状态的新思路和具体改进方案,结果证明增加行星轮和太阳轮的齿宽、模数和齿轮啮合角及提高润滑油粘度和粘压系数,可有效地改进齿轮润滑,减少齿面失效,提高行星齿轮传动机构的可靠性。     

齿轮润滑性能的多重网格技术应用研究

对齿轮的弹流润滑问题应用多重网格技术进行了数值计算与分析,并用于分析齿轮的弹流润滑性能。计算结果表明,多重网格技术应用于齿轮弹流数值计算具有收敛速度快、数值稳定性好等优点。增大齿轮的模数、传动比和压力角等参数,以及提高转速、增大润滑油粘度可以提高齿面间的润滑油膜厚度。     

轴流风机齿轮点蚀原因探讨

从润滑原理和齿轮自身特点出发,分析了轴流风机齿轮发生点蚀的原因和润滑油对齿轮点蚀的影响,结合现用润滑油品的使用效果,得出润滑油粘度选用不当对风机齿轮形成点蚀有加速作用的结论,据此结论提出风机齿轮润滑油品选用建议。     

齿轮油对齿轮接触疲劳寿命影响的试验研究

本文用两种不同添加剂的齿轮润滑油，在ＣＬ—１０Ｏ齿轮试验机上进行接触疲劳寿命对比试验，并进行数据的处理与分析，研究不同添加剂的润滑油对渗碳淬火齿轮和氮化齿轮接触疲劳寿命的影响。     

齿轮的润滑状态及润滑油的选择

本文介绍了齿轮的润滑状态和润滑油粘度的选择。并根据弹性流体动力润油理论计算膜厚比，分析润滑状态和对工作表面接触的影响，选择润滑油。     

Effect of Lubricant Degradation on Contact Fatigue

It is well known that contact fatigue is affected by contact pressure, frictional stress, residual stress, initial distribution of material flaws, and so on. The behavior of contact pressure and, primarily, the frictional stress is determined by the viscous properties of the lubricant used. It is also recognized that lubricants degrade while passing through lubricated contacts. Degradation of lubricants causes viscosity loss that, in turn, reduces the frictional stress and raises contact fatigue life. The objective of this study was to find out the extent to which lubricant degradation may change contact fatigue life of elastic surfaces completely separated by lubricant. The analysis was performed numerically based on the models of contact fatigue and lubricant degradation recently developed by the author. The results showed that contact fatigue life of solids completely separated by lubricants with the same ambient viscosity may vary significantly due to the specific way lubricants are formulated. In particular, contact fatigue life is strongly affected by the initial molecular weight distribution of the polymeric additive (viscosity improver) in the lubricant and contact operating conditions, which in some cases promote fast lubricant degradation caused by high lubricant shearing stresses.     

A study of rolling bearing fatigue life with mineral oil lubrication

Tests on mineral oil lubricated deep groove ball bearings show that there is an optimum lubricant viscosity to ensure maximum rolling contact fatigue life. The results are explained by lubricant film thickness measurements and the application of E.H.L. theory. The optimum lubricant viscosity increases with increase of load and decreases with reduction of speed.     

Some Effects of Additives on Rolling Contact Fatigue

To study the influence of lubricant physical and chemical properties on rolling contact fatigue, a variety of base stocks and additives were evaluated with a 4-ball type fatigue machine. The effect of viscosity was found to depend on the means by which a given viscosity was achieved. Although some commonly used EP and antiwear additives had a pronounced effect on fatigue life, the direction and magnitude of the additive effect depended on the particular additive and its concentration in the blend. In addition, it was observed that the additive effect depended on the choice of base oil and ball steel. These results indicate that the chemical properties as well as the physical properties of the lubricant, can be important in rolling contact fatigue.     

Effect of Lubricant Viscosity and Type on Ball Fatigue Life

Two separate investigations were conducted to determine the effect of lubricants on the fatigue life of M-1 tool steel balls in the rolling contact fatigue spin rig. In the first investigation four paraffinic mineral oils with viscosities of 5 to 113 centistokes at the 100F test temperature were used. Longer life was obtained with more viscous oil, life varying approximately as the 0.2 power of lubricant viscosity. In the second investigation of methyl silicone, a paraffinic mineral oil, a sebacate, a water base glycol and an adipate, each of which had a viscosity of about 10 centistokes at the 100F test temperature, were used. The 10 per cent life was about 40 times as great with the silicone (best) as with the adipate (poorest). The life results correlated fairly well with the pressure viscosity characteristics as estimated from lubricants of the same base stocks.     

Effect of oil environments on the initiation of fatigue cracks and propagation of small cracks in plain carbon steel specimens

In fatigue tests of plain carbon steel specimens in air, fatigue life is taken up mainly by the life in which a crack propagates from its initial size up to about 1 mm. This means that the behaviour of a small crack in the oil environment must be known in order to evaluate the effect of oils on fatigue life. In this paper, using a series of base oils of different viscosity grades, the effects of oils on fatigue damage are investigated in rotating bending fatigue tests of annealed 0.34% carbon steel plain specimens. Successive detailed observations of the specimen surface are made in order to study the fatigue processes of micro-crack initiation and small crack propagation. The physical background of the effect of oil environments on fatigue behaviour is shown, and a method for predicting fatigue life in oil environments is discussed.     

Rolling contact fatigue in lubricated contacts

This work presents and discusses the results of rolling contact fatigue tests (IP-300) with six different lubricants using a four-ball E.P. lubricant tester. These results tended to confirm the mechanism for rolling fatigue proposed by Jin and Kang. The lubricants tested were two mineral oils (SN 350 and SN 600) and four synthetic oils (PAG-9, PAG-12, PAO 6, and PAO X), the test machine used was a Four-Ball E.P., and the IP 300/87 standard was applied. The results indicated that: 1) lubrication has an important influence on the rolling fatigue life of mechanical components; 2) normally, in oils of the same family, the higher the viscosity is, the higher the rolling fatigue life is; 3) besides viscosity, other lubricant properties such as the pressure–viscosity coefficient (α), compressibility (B), and the EHL friction coefficient (γ), should all be taken into account for lubricated contact design.     

STUDY ON THE LUBRICATION FACTOR OF INVOLUTE SPUR GEARS

Based on a lot of numerical solutions to the problems of the thermal non-Newtonian elasto-hydrodynamic lubrication and some fatigue tests with rollers the lubrication factor of involute spur gears (called gear for short) is investigated. The results suggest that gear lubrication effects bear close relations to a dimensionless parameter D which is synthetically determined by gearing rotational speed,load,material,dimension and lubricant viscosity.When D<8,the gear fatigue life increases as the lubricant viscosity is increased;When D>8,however,the life decreases with the viscosity addition,which is in marked contrast to the lubrication factor Z recommended by the International Standard for Computing Cylindrical Gear Strength.At the end,a set of formulae for calculating gear lubrication factors suitable for different working conditions are advanced.     

基于Workbench的铆接连接件疲劳寿命的仿真分析

基于Workbench计算机仿真软件,开展了铆接连接件疲劳寿命的仿真分析.研究结果表明:疲劳破坏发生在铆钉孔两侧应力集中处,破坏发生位置的Mises等效应力值最大,仿真结果与疲劳试验结果吻合；在较高应力水平下,仿真分析的疲劳寿命与疲劳试验的寿命结果差异较小；在较低的应力水平下,仿真分析的疲劳寿命和疲劳试验的寿命结果差异...     

钢丝微动疲劳裂纹萌生寿命预测研究*

钢丝微动疲劳过程中,钢丝裂纹萌生特性直接影响其裂纹扩展特性,进而制约钢丝微动疲劳寿命,因此开展钢丝微动疲劳裂纹萌生寿命预测研究具有重要意义。基于有限元法、摩擦学理论和断裂力学理论,运用Smith-Watson-Topper（SWT）多轴疲劳寿命准则建立考虑磨损的钢丝微动疲劳裂纹萌生寿命预测模型,基于多种不同的钢丝疲劳参数估算方法对钢丝的微动疲劳裂纹萌生寿命进行了预测,并探究接触载荷、疲劳载荷、交叉角度及钢丝直径等微动疲劳参数对钢丝微动疲劳裂纹萌生寿命的影响规律。结果表明：基于中值法的预测结果最接近实际值;在微动疲劳过程中,钢丝微动疲劳裂纹萌生寿命主要与接触载荷和疲劳载荷相关。通过引入微动损伤参数建立简化的适用于钢丝绳的钢丝微动疲劳裂纹萌生寿命预测模型,通过与考虑磨损的预测模型计算结果进行对比验证了该模型的准确性。