四列圆锥轴承三维载荷分布与寿命计算

用梯形板单元模拟圆锥滚子并固接于内圈上，外圈和内圈分别贴合于轴承座及轧辊辊颈，从而多物体接触滚动轴承简化为两物体弹性接触问题，用三维弹性接触边界元法求解，获得四列圆锥轴承每列滚子偏载状况，准确描述轴承载荷特性与寿命关系。     

滚动轴承力学特性的有限元分析

基于ANSYS/LS-DYNA有限元分析软件,针对滚动轴承弹性接触的力学问题,以深沟球轴承6206为例,计算并分析在一定载荷条件下滚动轴承的力学特性及其运动状态。结果表明,有限单元法能够求解复杂的轴承动力学问题并具有较高的精度,为进一步研究滚动轴承弹性接触问题奠定了基础。     

轧机圆锥滚子轴承载荷的边界元法解析及实验研究

针对滚动轴承接触的特点,在轴承边界元法中采用赫兹接触理论对滚动体与轴承内、外圈的接触宽度进行修正。编制了三维有摩擦弹性接触的专用轴承边界元法计算程序,对轧机圆锥滚子轴承的载荷分布进行了数值模拟。采用轴承座直接测量法对轧机圆锥滚子轴承的径向和轴向载荷进行测试,并与数值模拟的结果进行了对比,实验测试结果与数值模拟的轴承载荷的分布规律基本一致,证明了边界元方法求解轴承载荷分布的正确性和有效性。     

游隙及载荷对滚动轴承载荷分布的影响

基于滚动轴承动力学、Hertz弹性接触理论和轴承宏观几何学,建立了滚动轴承的分析模型。分析游隙及载荷对滚动轴承载荷分布的影响。分析结果表明:随着径向游隙的减小,轴承的接触分布范围角增大;随着径向载荷的减小,轴承接触分布范围角减小;当轴承出现负游隙时,轴承内、外圈相对变形量较小,但轴承中滚动体的平均载荷增加,会导致轴承寿命降低。     

基于轴承边界元法的轴承座对轧机滚动轴承载荷的影响

阐述了在四物体有摩擦弹性接触边界元法的基础上,采用轴承边界单元模拟轴承接触单元及赫兹接触理论修正滚动体与轴承内、外圈的接触宽度的轴承边界元法.轴承座采用不同受力面厚度时对轧机四列圆锥滚子轴承的径向和轴向载荷的分布进行数值模拟,得到其对四列圆锥滚子轴承载荷分布的影响规律.并通过实验说明轴承边界元法在模拟滚动轴承载荷时的正确性和有效性.     

成对角接触球轴承摩擦力矩测量装置的设计

角接触球轴承在实际使用中通常成对安装,现有轴承摩擦力矩测量装置一般适用单套轴承,成对角接触球轴承摩擦力矩缺少合适的测量设备。针对这一问题,对滚动轴承摩擦力矩的影响因素进行理论研究与分析计算,在此基础上设计了成对角接触球轴承摩擦力矩测量装置。介绍了成对角接触球轴承摩擦力矩测量装置的原理、技术指标、结构、电气系统、软件系统,并以成对7038角接触球轴承为测试对象进行启动摩擦力矩和动态摩擦力矩测试试验,得到启动摩擦力矩和动态摩擦力矩随轴向载荷增大而增大的变化趋势。     

基于显式动力学的深沟球轴承弹性接触动态应力研究

滚动轴承是机械工业的重要基础件,其内部的动态应力状态对其寿命有着重大影响。针对滚动轴承内部弹性非线性接触的特点,以深沟球轴承6304为研究对象,建立了深沟球轴承全柔体弹性接触非线性动态有限元分析模型,采用显式动力学有限元法对深沟球轴承进行了转动过程非线性接触动态仿真,获得了深沟球轴承的运动学特性和轴承内部应力在轴承转动过程中的动态变化的特点和规律。结果表明,显式动力学有限元法可在满足高精度要求情况下求解滚动轴承内部的动态应力,为进一步研究滚动轴承的承载能力和寿命提供了有力的分析方法。     

滚动轴承刚柔多体接触动力学分析

以柔性多体动力学理论为基础,提出了以相对坐标描述刚柔多体接触滚动轴承的递推数值分析方法。以球轴承为例,研究了滚动轴承刚柔多体接触输出响应的动态特性。综合考虑滚动体与轴承内外圈滚道的时变接触刚度、柔性接触、摩擦、离心力等非线性因素,分析出转速、摩擦力和预紧力对滚动轴承的时变接触力和时变振动位移的影响。结果表明,以相对坐标描述刚柔多体接触滚动轴承的动力学模型,可以有效地解决滚动体与滚道间的时变接触振动响应和柔性接触等非线性接触动力学问题。     

基于ANSYS/LS-DYNA的滚动轴承仿真与分析

基于ANSY/LS-DYNA建立了滚动轴承的有限元模型,有效处理了考虑摩擦条件的接触问题,实现了滚动轴承显式动力学的运动过程仿真.并以6003深沟球轴承为例,进行了试算和相关参数的仿真与分析,结果表明,与滚动轴承运动的实际情况基本吻合.不同工况下的参数仿真分析是进一步研究故障轴承运动仿真与分析的基础.     

柔性轴承寿命的分析计算

假设柔性轴承的寿命符合韦布尔分布,应用赫兹弹性接触理论和滚动轴承额定动负荷理论进行柔性轴承的寿命分析。对影响柔性轴承寿命的几何因素和力学因素做了定量分析,推出了柔性轴承的可靠度同普通轴承可靠度之间的关系和柔性轴承接触寿命计算式,并编程计算了滚动轴承接触疲劳指数方程中的各物理量。     

A flat punch pressed against an elastic interlayer under conditions of slip and separation

The problem of a square-ended rigid punch bearing on an elastic half-plane through the medium of an elastically dissimilar interlayer is considered, under plane deformation. The interlayer is in frictional contact with both the punch and half-plane. Regions of slip and separation along the interface are found, and it is shown how these phenomena affect the stress state in the immediate neighbourhood of the contact. This problem is of direct, practical interest to the design of interfacial bearing pads employed in supporting glass plates in structural applications.     

Frictional Behaviors of Some Nitrogen Ceramics in Conformal Contact with Tin Coated Al-Si Alloy,Steel and MMC

The frictional behavior of certain nitrogen-containing ceramics, such as silicon nitride, alpha sialons, and beta sialons as journal materials were studied in conformal contact with a tin-coated Al-Si alloy (Al-Si/Sn), forged 1141 steel and a cast aluminum matrix composite with silicon carbide reinforcement (cast MMC) as bearing materials while lubricated with SAE WW30. A case-hardened 1016 steel was also tested with the Al-Si/Sn and cast MMC bearings under the same conditions. The friction values of the ceramic and the steel journal wear pairs were compared and their frictional behaviors were evaluated.

Silicon nitride and one of the beta sialons exhibited higher load-supporting capacities than the others when they were in contact with the 1141 steel bearings. The journal surface roughness was found to be very important when the journals were in contact with the Al-Si/Sn bearings. The frictional behavior of the ceramics and cast MMC pairs and the steel and cast MMC pairs were controlled by different wear mechanisms, namely for the former, hard particle pull-out and matrix plowing, and for the latter, iron transfer from the journal to the cast MMC bearing surface.     

A local error estimator using finite element residual and duality

A quasistatic frictional contact formulation is derived from a dynamic contact problem using time-discretized approximation, for which a compliant interface model of the contact surface is assumed. An a posteriori error estimator is developed by a Lagrangian formulation which is recast into a set of local problems with equilibrated normal stress. Hence, local errors are calculated by solving these local element-wise problems, and can be used to obtain optimal meshes through an adaptive hp-finite element method based on a priori and a posteriori error estimates. The theory is applied to representative test problems of frictional contact, and numerical simulation results are given to support the theoretical results.     

Experimental determination of the equivalent stress at the frictional surfaces of a slip bearing in a heavily loaded contact

The significant influence of the frictional forces on the bush deformation in a heavily loaded contact is shown. The results of comparative tests are presented. The coefficients for calculating the equivalent stress at the frictional surfaces of a slip bearing are determined.     

Prediction of the friction torque in grease lubricated angular contact ball bearings using grey system theory

The development of special grease makes it possible for angular contact ball bearings to operate at high speed and temperature; however, as an important performance parameter, friction torque of bearings lubricated with grease is much greater than that of bearings lubricated with oil-air, and heat generation due to frictional loss is also greater, so it is necessary to predict the friction torque occurring in grease lubricated angular contact ball bearings. Based on grey system theory, a new prediction methodology for bearing friction torque is proposed which capitalizes on the notion that the information about friction torque of angular contact ball bearing is generally poor, incomplete and uncertain. A grey prediction model, GM (1, N) model, is presented to predict the friction torque in grease lubricated angular contact ball bearings. Several experiments on the friction torque of grease lubricated angular contact ball bearings were conducted to model and validate the effectiveness of the GM (1, N) model through on-line and off-line approaches. Experimental results show that about 90% of bearing friction torque under varying speed can be predicted in the on-line prediction; above 85% of bearing friction torque under varying speed and different loads can be predicted in the off-line prediction. Comprehensive analysis shows that, the GM (1, N) model performs very well for both modeling data and model validation data under different loads, varying bearing speed and work cycles, the proposed methodology can be used to predict bearing friction torque with good accuracy and robustness.

     

ANALYSIS OF ROLLING BY ELASTO-PLASTIC FINITE DEFORMATION CONTACT BOUNDARY ELEMENT METHOD

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The actual contact area of moving surfaces

Hertzian contact is generally assumed when calculating the actual contact area of two surfaces. However, Hertz's formula is strictly only valid when there is no tangential stress in the region of contact. If the two surfaces are moving relative to one another then there will be frictional stress so that the assumption of Hertzian contact cannot be entirely valid. The twodimensional problem of contact with tangental stress is very difficult even for asperities with spherical symmetry. However, for shapes uniformly infinite in one direction it is tractable. The dependence of contact area on load is examined in this case and found to be generally dependent on the frictional force except for the case of circular cross section in which it is the same as for the frictionless problem. The significance of these results is discussed.     

Frictional heating of a half-space with cracks. I. Single or periodic system of subsurface cracks

The paper deals with the two-dimensional problem of frictional heating for an elastic half-space containing one or a system of periodic subsurface cracks. The generation of frictional heating in the region of contact is estimated by the use of sliding speed, frictional coefficient and contact pressure. The problem is reduced to a pair of singular integral equations which are solved numerically. The influence of the location of cracks on the stress intensity factor is investigated.     

交联超高分子量聚乙烯人工髋关节磨损仿真模拟

人工髋关节超高分子量聚乙烯（UHMWPE）关节面磨损仍是影响置换关节远期寿命的主要因素,其仿真建模是对关节模拟机磨损测试手段的重要补充,也是实现置换关节临床前性能评估的有效方法。由多向运动产生的交叉剪切效应是影响UHMWPE磨损的主要原因之一,也是仿真建模的关键。现有理论方法将磨损深度确定为滑动距离的函数,并将90°交叉剪切运动条件下的磨损作为度量基准计算不同角度下的交叉剪切效应,但尚未考虑接触应力变量对磨损深度的影响。针对以上问题,提出了在垂直交叉剪切运动条件下将磨损深度表示为摩擦功函数的方法。该方法利用UHMWPE摩擦因数与接触压力的定量关系计算摩擦因数并确定摩擦功,解决了UHMWPE磨损交叉剪切效应中滑动距离与接触应力的耦合问题。基于磨损仿真新模型研究了36 mm直径的交联UHMWPE髋关节,并与已有ProSim模拟机试验结果进行了验证。结果显示该仿真模型可准确计算体积磨损和线性磨损等磨损量以及髋关节载荷方向改变对磨损的影响。磨损新模型为进一步仿真模拟奠定了有效基础。     

A model for coulomb torque hysteresis in ball bearings

The frictional torque resisting rotation of an angular contact ball bearingg builds up from rest to its steady value through a small but finite angle of rotation. A similar transient torque is observed when the direction of rotation is reversed so that, in a bearing which undergoes oscillating rotations of small amplitude, the resistance torque traces out a hysteresis loop with angle of rotation. Following Dahl [AFO 4695-67-C-D158, Aerospace Corp. (1968)], the shape of the loop is expressed in terms of two parameters: (i) the initial and reversal gradient s and (ii) the steady-state torqueT_s. Theoretical expressions are derived for both s and T_s. s depends upon the elasticity of the bearing materials but not upon the frictional conditions at the contact interface whereas the opposite applies to T_s. Both depend upon the geometry of the bearing, particularly the conformity between the ball and race. Good correlation has been found between theoretical predictions and experiments carried out on three bearings of significantly different geometry.