斜齿轮参数化建模及接触应力的有限元分析

基于斜齿轮的啮合特点,通过UG软件建立斜齿轮参数化模型,利用Ansys Workbench软件对斜齿轮划分网格,施加载荷等前处理,得出了斜齿轮齿向接触应力分布图,从而进行齿轮强度校核。     

注塑机专用五轴机械手悬臂的有限元分析

利用Pro/M对某注塑机五轴机械手的横梁进行有限元分析,首先,提出了两种载荷施加方案,分别得出了悬臂的变形和应力云图,对两种方案进行比较,可以在一定程度上反映滚轮与悬臂接触区域的应力状况;其次,通过对悬臂梁和滚轮组件的接触分析,得出悬臂在接触区域的具体接触应力,验证了该悬臂的安全性。展现了Pro/Mechanica在有限元分析方面的优势,尤其是在曲面区域的划分上,通过对悬臂的有限元分析,可以看出在约束和载荷的施加上该分析方法与实际工作中的一致性。     

滚轮轴承的类型与结构

滚轮轴承是指其外圈不装入机座孔、轴承箱或轴承座内,而是直接在钢制轨道上滚动的轴承。其基本类型有螺栓型滚轮轴承、平挡圈型滚轮轴承、重型输送链条用滚轮轴承和行走机械用滚轮轴承。重点介绍了以上类型滚轮轴承的结构特点和使用情况。     

太阳能电池自动跟踪系统的设计

设计了一套以计时芯片和单片机为核心,进行太阳高度角和方位角计算,并利用步进电机驱动双轴机械跟踪系统,使太阳能电池板始终垂直于太阳入射角,从而提高太阳能的吸收效率的太阳能电池自动跟踪系统.该系统能够在每天视日结束后自动回到初始位置,第二天继续自动跟踪,从而消除积累误差,并采用步进电机驱动,使角度的调整更为准确.太阳每天的位置利用太阳轨道公式计算得出,进一步消除了天气的影响.     

基于ADINA的大负荷滚轮推车强度的仿真分析

将UG三维建模软件和ADINA软件相结合,分别建立了大负荷滚轮推车的整体和双滚轮的有限元模型.基于非线性接触算法对滚轮接触面的接触应力进行分析,对比两种情况下的计算结果,得到双滚轮的有限元结果与传统的赫兹理论较接近.同时对滚轮推车的结构静强度进行了计算,为大负荷滚轮推车的设计提供了理论依据.     

大负荷滚轮推车强度有限元分析

将UG三维建模软件和ADINA软件相结合,分别建立了大负荷滚轮推车的整体和双滚轮的有限元模型。基于非线性接触算法对滚轮接触面的接触应力进行分析,对比两种情况下的计算结果得到双滚子的有限元结果与传统的赫兹理论较接近。同时对滚轮推车的结构静强度进行了计算,为大负荷滚轮推车的设计提供了理论依据。     

斜齿轮齿向修形技术的研究

针对斜齿轮的啮合特点,设计了不同的齿向修形曲线,通过Pro/E 建立了修形齿轮的参数化模型,利用Ansys Workbench对修形齿轮进行网格划分,得出了修形斜齿轮齿向接触应力分布特性.校核了其接触强度.     

大载荷滚轮推车强度有限元分析

将UG三维建模软件和ADINA软件相结合,分别建立了大载荷滚轮推车的整体和双滚轮的有限元模型.基于非线性接触算法对滚轮接触面的接触应力进行分析,对比2种情况下的计算结果,得到双滚子的有限元结果与传统的赫兹理论较接近.同时对滚轮推车的结构静强度进行了计算,为大载荷滚轮推车的设计提供理论依据.     

非正交修形斜齿面齿轮传动接触应力计算研究

非正交修形斜齿面齿轮是一种具有普适性的交叉轴齿轮传动方式,目前还没有接触应力解析计算公式,只能依靠有限元软件进行接触应力计算。给出了其接触应力计算方法和相应的计算公式。首先,基于曲面啮合传动原理,推导了非正交修形斜齿面齿轮齿面方程;其次,建立含安装误差的接触分析坐标系,由齿面接触分析原理得到接触点及其曲率计算方程;最后,按赫兹接触理论推导出一般形式的接触应力解析计算公式,该接触应力计算公式可以计算正交与非正交、修形与非修形、直齿与斜齿等各种不同形式的面齿轮传动接触应力,通过编制程序快速计算出相应的接触应力。以某一设计参数的面齿轮副为例,应用提出的接触应力计算方法计算出接触应力,同时利用Abaqus有限元软件进行齿面接触应力计算,提取有限元计算的面齿轮齿面接触应力值,与解析计算公式的结果进行对比,两者误差为5. 23%左右。对比结果表明,给出的非正交修形斜齿面齿轮齿面接触应力计算方法与计算公式正确可行。     

滚轮滑轨磨损可靠性研究

滚轮滑轨的滚动接触在工程领域中普遍存在,实际应用表明滚轮或者滑轨磨损是主要的失效模式,滚轮滑轨磨损可靠性分析显得尤为重要。基于Archard模型和磨损可靠性模型,建立了接触应力及滑动距离的计算模型,确定了磨损系数和允许磨损量的选择依据,提出了滚轮滑轨磨损可靠性分析方法。通过实例,进行了理论工况下新型摆动导杆式抽油机中滚轮磨损可靠性分析,给出了滚轮磨损可靠度与工作时间的关系曲线,其分析结果为滚轮滑轨维护周期提供了依据。     

Fatigue life investigation of solid and hollow rollers under pure normal loading

Two solid and hollow cylindrical rollers in pure rolling contact subjected to pure normal loading have been modelled. Using a finite element package called ABAQUS, the stress and strain distributions in the two rollers in contact have been determined. The relative fatigue life of the hollow rollers compared to solid rollers has been investigated using the fatigue life model for rolling bearings developed by Ioannides and Harris. Different hollowness percentages have been studied: 20, 40, 60 and 80%. The hollowness percentage is the ratio of the diameter of the hole to the outer diameter of the cylinder. Both cases were studied – when the two rollers in contact are hollow and when only one of them is hollow while the other one is solid. Making the rollers hollow will result in redistribution of stresses over a larger volume in the contact zone due to the flexibility of the hollow rollers. That decreases the peak stress in the contact zone of the hollow cylinder when compared to the solid cylinder. Hollow cylinders have more flexibility when subjected to normal loading. And so, the stresses are redistributed so that the fatigue life is improved. The best stress redistribution and so fatigue life improvements have been found when both cylinders have around 60% hollowness. Copyright © 2007 John Wiley & Sons, Ltd.     

圆柱滚子凸度设计应用

分析了我国圆柱滚子轴承使用寿命比国外发达国家低的主要原因之一是滚子凸度设计应用问题,讨论了滚子凸型对接触压力分布的影响,指出滚子凸度的设计应用必须避免接触压力的奇异分布,并减小压力集中问题,通过理论分析和寿命对比试验得出:对数母线凸型是滚子凸度设计优先选用的凸型.     

Relative fatigue life estimation of cylindrical hollow rollers in general pure rolling contact

Solid and hollow cylindrical rollers in pure rolling contact have been modelled. The two rollers are subjected to a combined normal and tangential loading. The tangential loading is one‐third of the normal loading value. The finite element package, ABAQUS, is used to study the stress distribution and the resulting deformations in the bodies of the rollers. Then the Ioannides–Harris fatigue life model for rolling bearings is applied on the ABAQUS numerical results to investigate the fatigue life of the solid and hollow rollers. Using the fatigue life of the solid rollers as the reference fatigue life, the relative fatigue lives of hollow rollers are determined. Four main different hollowness percentages are been studied: 20, 40, 60 and 80%. The hollowness percentage is the ratio of the diameter of the hole to the outer diameter of the cylinder. For each of those hollowness percentages, two cases are studied – when the two rollers in contact are hollow and when one hollow roller is in contact with a solid roller. This study includes two main models: Model 1, where the two cylindrical rollers in contact are of the same size, and Model 2, where the two rollers in contact are not of the same size. The estimated relative fatigue lives of hollow rollers showed a great improvement of the fatigue life compared with solid rollers under the same loading conditions. This was a result of the redistribution of stresses in the contact zone in the case of hollow rollers. Redistribution of stresses over a larger volume of the roller body decreased the peak stress and reduced the volume under risk. Increasing the hollowness percentage from 20 to 60% increased the flexibility of the roller, and better stress distribution was achieved, which resulted in improving the fatigue life. Although 80% of hollowness rollers have more flexibility than 60% of hollowness rollers, the bending stresses (σ_b) on the inner surface of the rollers tend to decrease the fatigue life. Copyright © 2007 John Wiley & Sons, Ltd.     

基于ANSYS的四列圆柱滚子轴承接触应力和刚度分析

对四列圆柱滚子轴承的接触应力、变形以及径向刚度进行了研究.建立了四列圆柱滚子轴承的有限元三维模型,基于ANSYS和Hertz接触理论,阐述了建模过程中的关键步骤,结合短应力线轧机的应用实例,计算了轴承滚子、内圈的接触应力与变形分布,直观表达了交错排列滚子之间的应力分布情况,计算结果和Hertz理论值相比较,具有较好的一致性.通过计算不同载荷下的轴承变形（轴承内孔轴线的相对位移）,获得了轴承刚度随径向载荷变化的规律.     

Experimental Study of the Smoothing Effect of a Ceramic Rolling Element on a Bearing Raceway in Contaminated Lubrication

The effects of steel and ceramic rolling elements on protrusions from the raceway of a bearing were experimentally investigated. Such protrusions, which are normally caused by solid contaminants in the lubricating oil, create stress concentrations and lead to a reduction in the rolling contact fatigue life of the bearing. To compare the over-rolling effects of steel and ceramic rollers, experiments with steel discs with artificial dents on the surfaces were performed using a modified twin-disc machine. The results show that ceramic rollers can reduce the height of the protruded edge of an artificial dent more than steel rollers, which means that they are more effective in smoothing a damaged surface. The stresses at the contact were calculated by finite element analysis based on the deformed profile of the dented surface. The reduction in the stress level due to the smoothing effect of ceramic rollers is greater than that of steel rollers. According to the Lundberg–Palmgren bearing fatigue model, that smoothing ensures a significantly longer rolling contact fatigue life for a bearing. To put the idea into practice, a rolling ball bearing with two of its nine steel balls replaced with silicon nitride balls (referred to as a “partial hybrid bearing”) was run, together with a full steel bearing of the same model, on a bearing tester in a highly contaminated lubrication condition. The results show that the partial hybrid bearing suffers from less damage in terms of wear. The post-experiment examination of the damaged surface of the bearing raceway found that the surface of the partial hybrid bearing was smoother than that of the full steel bearing. This reveals the smoothing effect of the rolling ceramic element on the contaminant-damaged bearing surface.     

滚柱直线导轨副接触区的接触变形分析

针对机床中重要的运动结合部——滚柱直线导轨的接触区的接触变形区域,进行了受力分析,并把一种新的变形理论模型应用于滚柱直线导轨接触区的变形计算,通过有限元分析,验证了计算公式的正确性,同时还得到了接触区滚动体的圆弧母线与直母线相切处的受力接触变形图和应力图,为相应滚子的设计提供了一定参照。     

Influence of soft surface modification on rolling contact fatigue strength of machine element

Various surface modification methods have been employed in order to improve the tribological performance of machine elements. In this work, electroless Ni–P alloy plating and sulfurizing treatments were employed, and the surface modified steel rollers and ball bearings were fatigue-tested under a pure or free rolling contact condition. The fatigue lives of both rollers and bearings were improved by these surface modifications. The contact pressure and subsurface stresses of the surface modified rollers and bearings were analyzed. The reason why the rolling fatigue strengths of surface modified rollers and bearings were higher than those of the non-coated ones would be due to the smaller contact pressure and subsurface stresses by the smaller elasticity as well as the conformity of the plated layer.     

Macroscopic and microscopic changes in the surface layers of annealed and case-hardened steel rollers due to rolling contact

Measurements of the residual stress and observations of the microstructure at the surface and in the subsurface of rollers were performed during rolling contact fatigue tests of annealed 0.45% carbon steel and case-hardened nickel-chromium steel rollers. Compressive residual stresses in annealed rollers were induced by the rolling contact. With case-hardened rollers they were induced by heat treatment prior to the rolling contact fatigue tests. After the rolling contact fatigue tests the compressive residual stresses on the surface of the annealed rollers and in the subsurface of the case-hardened rollers relaxed; a characteristic substructure was formed by the stress cycles, which caused surface failure. It was confirmed that the microcracks leading to surface failure initiate on the surfaces of annealed rollers and in the subsurface of case-hardened rollers.     

三排柱式回转支承非理想Hertz接触特性分析

传统方法对三排柱式回转支承的滚柱与滚道间的接触分析都是基于Hertz接触理论,然而滚柱与滚道的实际接触超出了Hertz接触理论的范围。针对该问题,重点研究了滚柱与滚道的非理想Hertz接触特性,得出了接触变形及接触应力沿滚柱轴向的变化规律。结合McEwen关于圆柱体法向接触理论,推导了滚柱与滚道接触区内部的应力场各应力分量解析表达式,并讨论了滚道失效与应力之间的关联。最后,建立了滚柱与滚道接触的3D有限元模型,仿真结果表明,接触区的应力分布与解析解基本吻合,结论可为三排柱式回转支承的设计与制造提供参考。     

预负荷和无预负荷空心圆柱滚子轴承应力比较研究

根据接触力学理论,用有限元法对无预负荷和预负荷空心圆柱滚子轴承的接触应力和等效应力进行了分析,分析了过盈量和空心度对接触应力和等效应力的影响,比较了两种滚子轴承的接触应力和等效应力.结果表明,在相同几何和载荷条件下,过盈量合理的预负荷空心圆柱滚子轴承的应力情况好于无预负荷空心圆柱滚子轴承的应力情况,为无预负荷和预负荷空心圆柱滚子轴承的设计与应用提供了参考.