汽车轮毂轴承凸度有限元分析

用ANSYS软件对桑塔纳轿车前轮毂轴承进行有限元分析 ,确定合理的凸度形式及滚子与滚道的最佳凸度匹配关系 ,给出了滚子、内圈滚道最佳凸度控制方程。结果表明 :凸度形式及滚子与滚道的凸度匹配关系对轴承的载荷分布和承载能力有显著影响 ,最佳凸度控制方程对改进轮毂轴承凸度设计具有重要的指导意义。     

Effect of Roller Geometry on Roller Bearing Load–Life Relation

Cylindrical roller bearings typically employ roller profile modification to equalize the load distribution, minimize the stress concentration at roller ends, and allow for a small amount of misalignment. The 1947 Lundberg-Palmgren analysis reported an inverse fourth-power relation between load and life for roller bearings with line contact. In 1952, Lundberg and Palmgren changed their load–life exponent to 10/3 for roller bearings, assuming mixed line and point contacts. The effect of the roller–crown profile was reanalyzed in this article to determine the actual load–life relation for modified roller profiles. For uncrowned rollers (line contact), the load–life exponent is p = 4, in agreement with the 1947 Lundberg-Palmgren value, but crowning reduces the value of the exponent, p. The lives of modern roller bearings made from vacuum-processed steels significantly exceed those predicted by the Lundberg-Palmgren theory. The Zaretsky rolling-element bearing life model of 1996 produces a load–life exponent of p = 5 for flat rollers, which is more consistent with test data. For the Zaretsky model with fully crowned rollers, p = 4.3. For an aerospace profile and chamfered rollers, p = 4.6. Using the 1952 Lundberg-Palmgren value p = 10/3, the value incorporated in ANSI/ABMA and ISO bearing standards, can create significant life calculation errors for roller bearings.     

径向游隙对圆柱滚子轴承疲劳寿命的影响

应用经典的滚动轴承理论和“切片法”的基本思想,以某大兆瓦风电机组齿轮箱输出轴轴承为例,采用Romax Designer工程分析软件,计算了圆柱滚子轴承不同径向游隙时的轴承内部载荷分布、接触应力、套圈滚道当量动载荷和寿命,分析径向游隙对轴承ISO/TS 16281寿命的影响。研究结果表明：径向游隙不仅通过对轴承内部载荷分布、接触应力和套圈滚道当量动载荷的影响而对寿命产生影响,还通过对寿命修正系数等因素的影响而对寿命产生影响。研究结果可为滚子类轴承的优化设计提供参考。     

Probabilistic Stress-Life (P-S-N) Study on Bearing Steel Using Alternating Torsion Life Test

Probabilistic stress-life (P-S-N) studies using alternating torsion life test were conducted with the bearing steel JIS SUJ2/AISI 52100 having a hardness range of Rockwell C scale of 58-62 HRC to determine the existence of a fatigue limit for this through-hardened steel. One hundred and fifty (150) alternating torsion tests were performed at six torsion maximum shear stress amplitudes of 0.5, 0.63, 0.76, 0.80, 0.95, and 1.0 GPa. The number of specimens that were run at each stress amplitude varied from 19 to 33. There is no observable fatigue limit for JIS SUJ2/AISI 52100 bearing steel. On log-log plotted data, life is linear and is inversely proportional to shearing stress to a 10.34 exponent. The failure mode of the experiment is due to the conjugate tensile and compressive alternating stresses in accordance with alternating shearing stresses. The three-parameter Weibull life distribution function with a constant value of the Weibull slope m = 3/2 was found to have the best conformity followed by the log-normal distribution and the two-parameter Weibull distribution function. The shear stress-life exponent (A = 10.34) for JIS SUJ2/AISI 52100 bearing steel was independent of the Weibull slope.     

倒角参数对滚子弹流润滑性能的影响研究

工程上常对滚子摩擦副的滚子进行端部倒角,倒角参数包括倒角长度与倒角半径。取润滑油为Eyring流体,用多重网格技术研究了此类滚子的弹流润滑性能,研究表明:最小膜厚位置可能出现在修形起始位置和滚子最边缘。当最小膜厚出现在修形起始位置时为正常工作状态;当最小膜厚出现在滚子最边缘时膜厚很薄,即将润滑失效。进而分别讨论了倒角长度和倒角半径对弹流润滑性能的影响,研究表明:应根据工况参数通过弹流计算设计端部倒角参数,以优化滚子的润滑状态和载荷分布,实现全膜润滑。     

空测采样次数问题的研究

在定寿编谱等研究中,确定载荷谱轻重的分散遵循何种分布及科学合理地确定飞机空测采样飞行起落次数具有重要意义.文中以当量使用寿命作为判断载荷谱分散的标准,并根据t分布理论,针对载荷谱分散遵循对数正态分布和双参数Weibull分布,分别给出空测采样次数的判断标准,为飞机结构的定寿编谱研究提供依据.     

基于热-应力耦合的高速圆柱滚子轴承凸度值分析

考虑到圆柱滚子轴承在运转过程中温升对轴承性能的影响,基于滚动轴承动力学理论、摩擦学原理和热分析理论,利用ANSYS建立了圆柱滚子轴承热-应力耦合有限元分析模型,分析了对数修形滚子的凸度值对轴承温升和接触应力的影响以及径向载荷和转速对最优凸度值的影响。结果表明:滚子最高温度随凸度值增大而增大,最大接触应力随凸度值的增大先减小后增大;考虑耦合时轴承零件的接触应力大于未考虑耦合时的接触应力;考虑耦合时滚子最优凸度值随径向载荷和转速的增大而增大,未考虑耦合时滚子最优凸度值随径向载荷增大而增大,但不随转速增大而变化。     

A Fatigue Life Comparison of Two-Row Tapered Roller Bearings and Spherical Roller Bearings

Tests were run to compare the fatigue life of two-row tapered roller bearings to that of spherical roller bearings. Both bearing types had an outer diameter of 110 mm with the spherical roller bearing having a 22 percent larger dynamic radial load rating than the tapered roller bearings. All tests were run at 165 percent of the respective two-row dynamic radial load ratings. The results show that both the indirect mounting (double cup or outer ring) and the direct mounting (double cone or inner ring) tapered roller bearings gave significantly better fatigue lives than the spherical roller bearings. These results appear to contradict the present ISO 281 standard which assigns a 1.15 b_m rating factor to spherical roller bearings compared to a b_m rating factor of 1.10 for that of tapered roller bearings.     

对数母线圆柱滚子凸度量的有限元分析

以42724QT型铁路客车圆柱滚子轴承为分析对象,对其滚子进行对数母线凸度的分析,借助有限元软件ANSYS完成了在不同凸度量下的接触应力分析及比较,得到了一定载荷下的较优凸度量区间,同时进行了相同凸度不同载荷下的接触应力比较。结果显示,为避免"边缘效应",一定的载荷对应一个较优的凸度区间,并且理论凸度近似值与分析后得到的最优凸度有一定的误差,即使是对数母线的滚子,当载荷超出正常加载范围时,仍会出现"边缘效应"。     

对数修形圆锥滚子轴承接触副径向刚度分析

以Hertz弹性接触理论为基础,推导出对数修形圆锥滚子与滚道之间的接触变形公式,依据弹流润滑理论,建立对数修形圆锥滚子轴承滚子-滚道接触副等效刚度分析模型,通过实例对对数修形圆锥滚子轴承进行有限元静力学接触分析,得到滚子、滚道接触变形分布。结果发现:接触变形随滚子有效长度和等效曲率半径的增大而减小;等效接触刚度随着接触载荷的增大而增大,等效接触刚度随着滚子有效接触长度增大而呈线性增大,随着修形量增大变化很小。     

Y2—Hd20溢流阀的冲击寿命分析

本文根据导阀寿命是决定溢流阀可靠性的主要因素这一特点，设计了一个省时、省力、节约能源的试验台。在此基础上对溢流阀进行了在冲击载荷下的加速寿命试验。试验数据分析表明，溢流阀的失效概率密度函数为两参数Ｗｅｉｂｕｌ分布。通过参数估计得到其形状参数、特征寿命、平均寿命等可靠性指标。     

对数母线滚子光弹流润滑的实验研究

为了研究对数母线滚子凸度量对滚子摩擦副润滑油膜的影响 ,本文在自制的有限长线接触光干涉弹流试验机上 ,测量了中载、富油润滑和纯滚动工况下对数修形圆锥滚子与玻璃盘之间的油膜形状与膜厚。实验结果表明对数母线轮廓滚子的凸度量对其端部的油膜厚度和膜形分布有较大的影响 ,在给定的工况条件下 ,存在一个使滚子轴向油膜厚度最为均匀的最佳凸度量 ,此最佳凸度量比在相同工况条件下用静弹性接触力学方法求得的最佳凸度量大     

基于两重威布尔分布的铸造造型机可靠性分析

为了定量分析铸造车间造型机故障的分布规律,并为其可靠性分析提供理论依据,收集设备故障数据,确定其服从标准威布尔分布,并进行参数拟合.在此基础上,建立了两重威布尔混合分布模型,通过图解法得到参数估计初始值,利用非线性最小二乘法进行参数估计优化.比较两参数威布尔、两重威布尔图解法以及非线性最小二乘法得到的参数,得出混合模型非线性最小二乘法参数估计值最为精确.根据已知参数估计值,最终确定该造型机可靠性函数,为其可靠性指标的进一步计算提供信息.     

Effect Of Roller Profile On Cylindrical Roller Bearing Life Prediction—Part II Comparison of Roller Profiles

Four roller profiles used in cylindrical roller bearing design and manufacture were analyzed using both a closed form solution and finite element analysis (FEA) for stress and life. The analyzed roller profiles were flat, end tapered, aerospace, and fully crowned and loaded against a flat raceway. Four rolling-element bearing life models were chosen for this analysis: those of Weibull; Lundberg and Palmgren; Ioannides and Harris; and Zaretsky. The flat roller profile without edge loading has the longest predicted life. However, edge loading can reduce life by as much as 98 percent. The end-tapered profile produced the highest lives, but not significantly higher than those produced by the aerospace profile. The fully crowned profile produced the lowest lives. Except for the flat roller profile, the predicted lives with the FEA method exceed those with the closed form solution. The fatigue limit proposed by Ioannides and Harris equates to one-half the value of a compressive residual stress that may exist in a rolling bearing steel.     

圆柱滚子轴承外滚道精研质量分析

针对圆柱滚子轴承外滚道精研时存在的质量问题,对3MK3412精研机油石夹进行了改进,使油石精研时不在夹子内左右移动,并使油石形状由方形变成了Z形,消除了外滚道凹心问题,提高了轴承的使用寿命、旋转精度以及合套率。     

A New Life Theory for Rolling Bearings—By Linkage between Rolling Contact Fatigue and Structural Fatigue

Based on a linkage between rolling contact fatigue and structural fatigue, a new life theory for rolling bearings has been proposed using the three-parameter Weibull distribution function. A minimum life is introduced as the third parameter, which may be considered independent from the statistical strength of material. The following are the new findings: (1) Reliability functions and life equations were introduced for the rolling bearing races and the life test specimens made of the same material (JIS SUJ2/AISI 52100), and the linkage between them has successfully been established by using linkage factors. (2) The 90% load rating and rating life formulas for the races as well as for the whole bearing were developed. (3) Newly introduced 100% load rating and rating life formulas were postulated by introducing the minimum lives for the life tests and theoretical research. (4) For the ratios of each load rating between the test results on the grease-lubricated deep-groove ball bearings and the new life theory, the linkage factors were determined as β = 2.4 and β′ = 2.16 for 90 and 100% load ratings, respectively. (5) A reduction factor λ for 100% load rating was determined as λ = β′/β = 0.9.     

圆柱滚子轴承滚动体新的修形曲线

基于对传统修形理论的认识，用有限元方法对滚动轴承进行分析，提出了新的修形方法，获得了滚动体新的修形曲线，并给出新的修形曲线的一个算例，有限元分析表明，指数曲线与对数曲线一样，可以避免滚子两端的边界应力集中。     

高频轻载自润滑关节轴承加速寿命试验方法

为在短时间内获得高频轻载自润滑关节轴承的寿命信息,通过增大载荷的方式建立了加速寿命试验模型,进行了2组恒定应力加速寿命试验。采用韦布尔分布对关节轴承寿命进行描述,并借助最小二乘法对韦布尔分布函数的2个参数进行估算,确定出关节轴承可靠性寿命的相关指标,最终计算出基准载荷下关节轴承的可靠性寿命。数据统计结果表明,关节轴承的寿命服从韦布尔分布,其加速模型符合逆幂律关系,从而验证了在不改变失效机理的前提下对高频轻载自润滑关节轴承进行载荷应力加速寿命试验的可行性,极大地提高了产品寿命的预测效率。     

电厂球磨机传动齿轮的可靠性研究

根据球磨机的实际故障数据,分别采用概率纸法和线性回归分析方法,得出传动齿轮的寿命符合两参数威布尔分布,并求出其可靠性指标.     

无失效数据的可靠性评估和寿命预测

提出一种无失效数据可靠性评估和寿命预测方法 ,给出其可靠度和使用寿命的置信下限。该方法在Weibull分布形状参数下限已知的情况下 ,能将所有无失效寿命数据进行累加 ,大大提高可靠性分析的精度 ;而在对数正态分布标准差上限已知的情况下 ,可以充分发挥对数正态分布的可靠度和使用寿命置信下限较高的优点。此外 ,还建立对数寿命标准差和Weibull分布形状参数之间的关系式 ,从而能够根据工程上积累的大量对数正态分布标准差上限的数据求得Weibull分布形状参数下限 ,反之亦然。本文方法易于计算 ,便于工程应用