Rolling Element Bearing Contact Geometry Analysis

Rolling element bearings are subjected to a variety of loads during the operation of machinery. Raceway contact geometries should be designed and analyzed in a manner which accurately models internal contact stress distributions for these different load cycle conditions. To properly determine contact stresses, analyses should determine the orientation of rolling elements relative to the raceways through consideration of load, bearing alignment and bearing internal geometry. Since design loads are not always well defined and machinery upgrades may increase loads, contact geometry designs should have sufficient flexibility to handle conditions differing from the initial design loads. An analytical procedure with examples is discussed.     

粗糙表面弹性微动接触数值研究

由于实际工程表面多为粗糙表面,这里研究了粗糙表面对微动接触中压力和切向应力的影响.研究接触过程中法向载荷保持不变,切向载荷为周期性的交变载荷.首先,建立接触算法和模型,其算法核心是利用共轭梯度法(CGM)计算微动接触中的表面压力及切向应力并使用快速傅里叶变换(FFT)加快计算速度.然后,在验证算法正确的基础上,分析正弦...     

车削真实粗糙表面的弹塑性接触有限元分析

目前表面模型主要以统计数学方法和分形方法居多,不能真实的反应表面特征.通过Wyko NT1100形貌测量仪获得车削表面的形貌数据,利用最小二乘法对Bad点和噪声点进行拟合插值处理,然后通过逆向建模得到真实粗糙表面模型,运用有限元方法,研究了弹性阶段和弹塑性阶段无量纲化接触面积和位移随无量纲化载荷的变化关系.结果表明:利用测量数据格式与CATIA V5之间联系,可以建立真实粗糙表面的模型;在弹性接触阶段,无量纲化接触面积和位移与无量纲化载荷之间近似成线性关系;而在弹塑性接触阶段,当弹塑性切向模量Et较大时,无量纲化接触面积和位移与无量纲化载荷之间才近似成线性关系.当载荷一定时,Et越小,接触面积和位移越大,对于一定接触面积和位移的载荷也越大.     

On the Modeling of Elastic Contact between Rough Surfaces

The contact force and the real contact area between rough surfaces are important in the prediction of friction, wear, adhesion, and electrical and thermal contact resistance. Over the last four decades various mathematical models have been developed. Built on very different assumptions and underlying mathematical frameworks, model agreement or effectiveness has never been thoroughly investigated. This work uses several measured profiles of real surfaces having vastly different roughness characteristics to predict contact areas and forces from various elastic contact models and contrast them to a deterministic fast Fourier transform (FFT)-based contact model. The latter is considered “exact” because surfaces are analyzed as they are measured, accounting for all peaks and valleys without compromise. Though measurement uncertainties and resolution issues prevail, the same surfaces are kept constant (i.e., are identical) for all models considered. Nonetheless, the effect of the data resolution of measured surface profiles will be investigated as well. An exact closed-form solution is offered for the widely used Greenwood and Williamson (GW) model (Greenwood and Williamson, Proceedings of the Royal Society of London A, vol. 295, pp. 300–319), along with an alternative definition of the plasticity index that is based on a multiscale approach. The results reveal that several of the theoretical models show good quantitative and qualitative agreement among themselves, but though most models produce a nominally linear relationship between the real contact area and load, the deterministic model suggests otherwise in some cases. Regardless, all of the said models reduce the complicated surface profiles to only a few key parameters and it is therefore unrealistic to expect them to make precise predictions for all cases.     

The Effect of Scale-Dependent Hardness on Elasto-Plastic Asperity Contact between Rough Surfaces

Statistical methods are used to model elasto-plastic contact between two rough surfaces using a recent finite element model of elasto-plastic hemispherical contact and also recent advances in strain gradient modeling. The elasto-plastic hemispherical contact model used to model individual asperities accounts for a varying hardness effect due to deformation of the contact geometry that has been documented by other works. The strain gradient model accounts for changes in hardness due to scaling effects. The contact between surfaces with hypothetical material and surface properties, such as the elastic modulus, yield strength, and roughness are modeled. A model is also constructed to consider a variable asperity contact radius to evaluate if the strain gradient model will affect it differently. The models produce predictions for contact area, contact force, and surface separation. The strain gradient effects decrease the real area of contact and increase the average contact load in comparison to the model without these effects. The strain gradient model seems to have a larger influence on the predictions of contact load and area than does considering a variable asperity contact radius for the cases considered in this work.     

基于ANSYS的斜齿轮接触有限元分析

通过接触问题有限元基本理论的研究,应用大型有限元分析软件ANSYS建立多齿对啮合斜齿轮接触有限元模型,对其进行接触非线性有限元分析。计算结果准确直观,为斜齿轮接触应力分析和强度校核提供了更加快速有效的方法。     

箔带轧制的三维接触有限元分析

基于对三维多体接触问题有限元混合法基本原理及接触面的定解条件和判定条件的分析 ,本文将箔带轧机辊系及轧件组成的辊带系统视为三维多体接触问题 ,建立了接触有限元分析模型。对某厂四辊铝箔轧机初轧工况进行了数值计算 ,求得了辊缝内轧制压力的真实分布规律 ,充分揭示了箔带轧制过程中非轧制辊面存在压靠的事实。最后 ,针对来料板凸度对轧件板形的影响进行了有限元仿真分析 ,得出了与轧制规程图分析法一致的结论     

三环减速器的PATRAN-NASTRAN接触有限元分析探讨

利用UG、HYPERMESH、PATRAN、NASTRAN等软件联合仿真,分析了桌型三环减速器轮齿啮合传动接触状况.分析结果和实际工况吻合,验证了这套联合仿真的可行性,为建立高效、合理的有限元分析模型提供了参考,为以后相关人员做类似分析,提供一定的借鉴价值.     

基于齿轮箱整体模型的齿轮有限元接触分析

提出了一种应用叠加原理计算齿轮箱整体变形的方法,包括箱体、轴承、传动轴和齿轮的变形。重点阐述了利用ANSYS刚体耦合功能生成齿轮箱体柔度矩阵,建立柔度矩阵、载荷向量、变形向量三者关系方程,从而计算箱体变形的方法。以风力发电增速器齿轮箱为例,分析齿轮箱整体变形对支点反力和齿面接触应力及齿根弯曲应力的影响。     

接触分析在车轮弯曲疲劳有限元分析中的应用

利用有限元接触分析方法,建立车轮、试验轴、螺栓连接件的有限元模型,施加合理的载荷与边界条件,模拟车轮弯曲疲劳试验。通过有限元分析软件ANSYS,建立模型、设置接触对与相关参数,得出车轮高应力区域与各应力值。运用疲劳寿命计算理论中的名义应力法及ANSYS软件估算车轮疲劳寿命,且两数据基本一致。与车轮弯曲疲劳试验结果比较表明:在疲劳寿命计算理论与ANSYS软件估算的疲劳寿命内车轮均没有破坏。从而验证了运用接触分析有限元法预估车轮寿命的有效性,为以后的结构改进起到了指导作用。     

接触角和横向载荷对轮轨粘着的影响

应用多层多支子结构技术建立轮对与轨道的多体接触模型,采用参变量变分原理和数学二次规划法求解轮轨接触力,根据不同的接触角和横向载荷计算得出轮轨接触力分布,分析接触角和横向载荷对纵向摩擦力(牵引力)以及粘着系数的影响。计算结果表明,轮对承受横向载荷时,轮轨接触点对之间摩擦力的方向在粘着区和蠕滑区有明显的不同,在粘着区其方向与钢轨纵向夹角较小,而在蠕滑区其方向与钢轨纵向夹角较大;当接触角较小时,粘着系数随着横向载荷的增加而减小;当接触角较大时,随着横向载荷的增加,粘着系数先增加后减小;在直线段粘着系数随着轮对承受横向载荷的增加而减小,在曲线段选取适当的横向载荷能够提高粘着系数。     

基于精确模型的斜齿轮接触应力有限元分析

在 Pro/ E中通过实例阐述了斜齿轮的精确建模方法 ,并介绍了具体的设计原理 ,将生成的一对齿轮进行标准安装生成啮合模型。通过 Pro/ E与 ANSYS的数据交换接口 ,把啮合模型的几何数据导入 ANSYS中 ,并转化成由节点及元素组成的有限元模型 ,运用完全牛顿 -拉普森方法进行接触应力的静力学求解 ,并介绍了算法原理。本文充分展示了 CAD与 CAE的结合应用     

机床导轨表面接触模型的有限元分析

为寻求机床导轨结合面不同粗糙信息下的动态特性,分形粗糙表面数值模型和实测粗糙表面二者的相关性,需对各种相关参数下的粗糙表面进行接触分析。运用有限元分析软件ANSYS,针对粗糙表面三维模型,分析不同参数表面的接触行为,以期寻找出不同粗糙信息接触形态特征参数之间的关系,并证明分形数值模拟能真实表征工程粗糙表面。     

O形圈轴对称超弹性接触问题的有限元分析

本文采用罚单元接触算法,建立了O形橡胶密封圈的轴对称超弹性接触问题的非线性有限元分析模型,结合国际上通用的有限元分析系统ANSYS程序,对多种型号的O形圈进行了有限元分析,为橡胶密封件的设计计算提供了一条新途径。     

螺旋桨轴毂复合联接结构接触问题的非线性有限元分析及结构尺寸优化

针对航空工业产品使用的情况分析:要求其在保证承载的前提下,在设计中尽可能使其结构紧凑或减重.利用ANSYS软件建立一种新型螺旋桨轴毂复合联接结构的有限元接触模型,并以其复合结构中关键零件弹性环的半锥角及宽度为设计变量、弹性环的最大应力为状态变量,对弹性环的结构尺寸进行优化分析,为设计一种能满足航空行业中使用要求的螺旋桨轴毂复合联接结构提供理论分析基础.     

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。     

支撑变形下弧齿锥齿轮传动的承载接触有限元分析

转子的变形会对弧齿锥齿轮传动的接触轨迹及传动误差产生影响,从而影响传动的平稳性和可靠性。在传动系统弯扭耦合振动分析的基础上,获得弧齿锥齿轮的支撑变形量,并将其等效为齿轮副的安装错位量。基于加载接触有限元分析原理,利用MATLAB自编有限元程序,给出了考虑支撑变形的弧齿锥齿轮承载接触分析方法。以一对弧齿锥齿轮为对象,研究其在一个啮合周期内小齿轮齿面最大接触应力和齿根最大弯曲应力的变化情况,为高质量弧齿锥齿轮传动提供了一种有效的设计与分析方法。     

A Method for Determining the Convergence under Contact between a Sphere and a Flat Surface of a Workpiece under Small Loads

A unified analytical dependence for determining the full convergence at the contact between the sphere and flat surface of has been obtained and experimentally confirmed. It is valid both under the conditions of purely elastic deformation and elastoplastic deformation.     

A Brief Examination of Factors Affecting Tractive Friction Coefficients of Spheres Rolling on Flat Plates

The use of steel ball-bearing balls in a new variable speed friction drive has given impetus to the study of factors governing their tractive capacity. The coefficient of tractive friction, defined as the ratio of tractive force to normal force at a specified slip rate, was observed to depend on lubricant properties and ball diameter, but to be relatively independent of normal load and rolling velocity. Coefficients of 0.08 were found to be attainable using conventional lubricants.