角接触球轴承高速运转时热特性有限元分析

针对角接触球轴承在高速运转时因温度过高而导致失效的问题,对其热特性进行了研究。在研究中,建立角接触球轴承的有限元模型,应用热力学理论计算轴承的生热率和对流换热系数,进行热特性有限元分析,得到角接触球轴承在2 000 r/min转速时的温度场。所做研究为通过润滑冷却系统控制角接触球轴承温升提供了技术参考。     

风力发电机组增速箱斜齿内啮合齿轮副接触强度分析

因强度不足而使齿轮磨损失效是风力发电机组增速箱中渐开线斜齿内齿轮啮合传动中常见的问题。遵循接触疲劳强度有限元分析基本流程,利用Pro/E建立斜齿内齿轮的三维立体模型并导入ANSYS分析软件中。通过对齿轮对进行接触非线性有限元分析,获得接触应力云图并判断斜齿内齿轮啮合瞬间最大应力发生的轮齿部位,确定最大应力值,并与传统齿轮强度计算方法计算出的结果进行比较,为齿轮的设计提供了理论依据,为日后风机的设计奠定坚实的基础。     

超越离合器滚动接触状态的三维有限元分析

基于超越离合器的CAD实体几何模型，建立了由摆杆、滚拄和星轮组成的摩擦传动组合体的三维有限元计算模型，进行了滚动接触状态分析，得到了各接触体的法向接触应力、切向接触应力和接触变形，并研究了接触体之间的摩擦系数对接触状态的影响规律，为超越离合器的磨损研究提供了依据。     

基于Pro/E和ANSYS的渐开线齿轮的参数化精确建模及接触分析

介绍了Pro/E建模软件进行渐开线齿轮精确建模的参数化方法及步骤,使得建模更加方便,其中利用渐开线方程,保证了渐开线齿轮齿廓的准确性。利用Pro/E与ANSYS的专用接口,将在Pro/E中建立的实体模型方便地导入到ANSYS中,进行网格划分、加载及求解。通过对于一个个间断的啮合点的接触应力的静力学分析,从而实现对单对轮齿从齿根到齿顶的连续啮合过程中接触应力的仿真分析,进一步了解齿轮啮合过程中从齿根到齿顶接触应力的变化规律,从而验证了ANSYS进行有限元接触分析的精确性,为齿轮的优化设计提供了理论依据     

Experimental Study of Four-Point Contact Ball Bearing with Deformable Rings

When a ball bearing is designed with thin rings or is mounted in a flexible housing, the assumption of rigid rings is not true anymore. In this article, an experimental study is presented and a comparison with a numerical model is performed. The numerical approach is based on the coupling between a semi-analytical code and a finite element (FE) model that computes the deformation of the rings and housings. The numerical model accounts for ring ovalization, raceway opening, change of conformity, and structural displacements of the whole assembly. The experimental setup allows investigation of the load–displacement behavior of a four-point contact ball bearing submitted to a static thrust loading. Displacements are measured by an optical method (stereo-correlation) that enables comparison of the surface deformation of the two tested bearings and computation of the rigid-body displacement of the inner ring with respect to the outer ring. A comparison between experimental results, numerical results, with and without consideration of ring and housing stiffness, is presented. The numerical results show the importance of the housing stiffness in the modeling, even with standard ball bearings with relatively large and thick rings. Good agreement between measured quantities and numerical results was found. This permits the prediction of the real nonlinear bearing stiffness (load–displacement curve) with a reasonable margin of error.     

预紧高速角接触球轴承运行刚度研究

基于滚动轴承拟静力学分析理论,从微观的角度探讨定位预紧下轴承内外圈位移存在约束时其内部的动力学状态;以B7004轴承为例,分析预紧方式对角接触球轴承运行刚度的影响,并利用电涡流位移传感器、LMS数据采集分析仪等仪器,在12MD60Y6型号电主轴上进行轴承刚度测试,对理论关系进行验证。结果表明:理论值能准确描述轴承运行刚度变化规律;定位预紧相比定压预紧更能提高轴承的支承刚度。     

边界润滑下滑动接触表面破坏行为的数值分析

针对边界润滑条件，本文用有限元方法分析了当滚动接触处于准静态情况下，接触表面覆盖有水边界膜而且接触区内存在微观突起和微观裂纹的接触状态，阐明了液体对表面微观裂纹的影响。分析结果表明液体的存在改变了接触区的受力状态，表面裂纹造成接触区应力分布的不连续；有水存在时，最高接触压力降低并且分布均匀，但造成应力强度因子K1增大，促进裂纹的扩展。     

Torque Variations in Instrument Ball Bearings

Disturbances in the torques and motions in angular contact instrument ball bearing pairs are described and analyzed. Among others, a motion of the ball retainer, analogous to dry friction whirl, is attributed to frictional coupling between balls and retainer, and an interaction between bearings, resulting in several low frequency perturbations, is explained in terms of ball errors. Experimental confirmation is obtained.     

An Improved Approach for 3D Rolling Contact Fatigue Simulations with Microstructure Topology

Several 2D and 3D numerical models have been developed to investigate rolling contact fatigue (RCF) by employing a continuum damage mechanics approach coupled with an explicit representation of microstructure topology. However, the previous 3D models require significant computational effort compared to 2D models. This work presents a new approach wherein efficient computational strategies are implemented to accelerate the 3D RCF simulation. In order to reduce computational time, only the volume that is critically stressed during a rolling pass is modeled with an explicit representation of microstructure topology. Furthermore, discontinuities in the subsurface stress calculation in the previously developed models for line and circular contact loading are removed. Additionally, by incorporating a new integration algorithm for damage growth, the fatigue damage simulations under line contact are accelerated by a factor of nearly 13. The variation in fatigue lives and progression of simulated fatigue spalling under line contact obtained using the new model were similar to the previous model predictions and consistent with empirical observations. The model was then extended to incorporate elastic–plastic material behavior and used to investigate the effect of material plasticity on subsurface stress distribution and shear stress–strain behavior during repeated rolling Hertzian line contact. It is demonstrated that the computational improvements for reduced solution time and enhanced accuracy are indispensable in order to conduct investigations on the effects of advanced material behavior on RCF, such as plasticity.     

润滑材料特性对接触疲劳裂纹的影响

在边界润滑条件下，当接触表面的液体不足以形成稳定的润滑膜，此时研究接触特性不同于弹流润滑。液体渗入到表面裂纹中必然对裂纹的扩展产生影响。本文用线弹性断裂力学理论，采用液－力耦合二维有限元方法分析了滚动接触微观裂纹受力状态，研究了在不同润滑剂特性影响下裂纹尖端应力强度因子的变化趋势，同时考虑了裂纹倾斜角和摩擦系数变化的因素，阐明了润滑剂对表面微观裂纹尖端及接触区域的影响。     

角接触球轴承的静态接触分析

介绍了基于经典Hertz弹性接触理论的解析计算方法和有限元仿真分析法.实例计算结果表明,在轴承工况相同的条件下,两种分析方法得到的接触特性参数的一致性较好,但各有特点.解析计算法编程复杂、解算难度大,只能算出接触区的主参数,而有限元法边界设置十分复杂、技术性强,可仿真轴承接触区的工作状态,且表达形象、直观.     

三点接触球轴承失效分析

针对某三点接触球轴承使用中提前失效的问题,对其进行了外观检查、金相分析、硬度检测和材质检验,排除了因材质问题引起失效的可能。通过失效分析以及对轴承所受轴向载荷的测量和钢球与外圈最大接触应力的计算发现,轴向载荷过大是导致轴承失效的主要原因。     

Non-Linear Transient Stability Analysis of a Rigid Rotor Supported on Hydrodynamic Journal Bearings with Rough Surfaces

Non-linear transient stability analysis has been performed to study the sub-synchronous whirl stability of a rigid rotor supported on two symmetric hydrodynamic bearings with rough surfaces subjected to a unidirectional constant load. A Reynolds type equation for finite hydrodynamic bearings, with different models of rough surfaces, has been solved using the stochastic finite element method. The trajectories of the journal center have been obtained by solving the equations of motion of the journal center by the fourth-order Runge-Kutta method. Results show an increase in the stability with transverse roughness and a decrease in the stability with isotropic roughness. A small improvement in stability is obtained with longitudinal roughness.     

高速角接触球轴承接触角的求解分析

在系统分析角接触球轴承动态特性辅助方程组的基础上,明确了各辅助方程最终都是接触角的函数的规律,建立了变量传递关系图.根据高速角接触球轴承运转时内、外接触角的变化,提出了基于接触角迭代的球轴承动态特性求解方法,将动态方程组变为接触角和接触变形的函数形式,并总结出了选取接触角初始值的一般规律,使得接触角初始值的选取接近真实解,缩短了迭代的求解过程.最后通过算例说明了本方法的可行性.     

Influence of Mixed-Lubrication and Rough Elastic-Plastic Contact on the Performance of Small Fluid Film Bearings

A previously developed deterministic elastohydrodynamic (EHD) numerical model for small fluid film bearings functioning in the mixed lubrication regime is extended in this work by considering the rough contact. Several simplifying hypotheses are made: the shaft is considered rigid and smooth, turning at low speeds (isothermal regime), and the pad is assumed to have an elastic-perfectly-plastic behavior. The Reynolds equation is solved on a very fine mesh and the elasto-plastic pad deformation caused by the hydrodynamic pressure is taken into account. A deterministic active set-based method is used for determining the contact pressure, the contact extent, and the corresponding deformation. The results are presented for a partial journal bearing configuration, with a linear shaft velocity of 0.47 m/s under specific pressures varying up to 50 MPa. Two pad materials are considered, and the lubricant is either isoviscous or piezoviscous oil. The simulation results, presented as a function of the bearing specific pressure, include eccentricity, the film thickness, the friction torques, the contact extent, etc. Stribeck curves showing the evolution of the friction coefficient in the hydrodynamic and mixed lubrication regimes are also discussed.     

Elasto-Plastic Contact of Rough Surfaces

An isothermal elasto-plastic asperity contact model is developed and presented in this paper, which deals with micro plastic flows of materials and the influence of the elasto-plastic deformation of materials on the behavior of contacting surfaces. The model is solved with the incremental form of a simplex-type algorithm. The von Mises yield criterion is used to determine the onset of the plastic deformation. The effectiveness and validity of the model are studied through analyzing a Hertzian contact problem. Substrate stresses are calculated and differences are observed. Furthermore, the contact pressure, real area of contact, and average gap of real rough surfaces under the elastic, elastic-perfectly-plastic, and the elasto-plastic contact conditions are numerically investigated and the results are compared.     

角接触球轴承的温度场分析

研究轴承的发热、传热过程,可为轴承动态油膜的热失稳研究提供理论支持。建立滚动轴承油气或油雾润滑下的热节点传热模型,利用热网络法建立温度场计算模型,并考虑轴承转速、载荷、离心力和自旋对温升的影响,计算出各节点的温度。结果表明,角接触球轴承的热生成与轴承转速、载荷、离心力和自旋有关,转速越高,载荷越大,则轴承的温升越高;随着转速增大,离心力和自旋对温升的影响增大,尤其高速情况下,离心力和自旋对轴承温升的影响不可忽略。     

球轴承接触角测量原理分析

接触角是角接触球轴承最重要的几何参数。分别介绍了运用轴承几何学原理和轴承运动学原理检测球轴承接触角的方法。其中,几何学检测法是通过检测轴承径向游隙间接获得接触角,运动学检测法是利用球轴承旋转套圈与保持架间的速度差检测接触角。     

双台阶钻柱螺纹联接弹塑性接触特性数值仿真

建立了双台阶钻柱螺纹接头有限元模型,采用弹塑性接触有限元混合法开发了钻柱螺纹接触特性分析程序,并对双台阶钻柱联接螺纹进行了应力应变分析,求得联接状态下由预紧力以及轴向力、内外压力、弯矩和扭矩所引起的螺纹联接部位的位移场和应力场,为评价其承载性能及密封性能提供了一种数值方法。