滚子轴承温度分布的数值计算与应用

在摩擦学和传热学理论的基础上,进行了滚子轴承内部温度分布的研究.运用计算流体力学分析软件FLUENT对以风机轴承、转子、轴承座为一体的系统建立了温度场数值仿真模型.对5种不同润滑脂容积比状态的模型进行了轴承温度场的数值模拟,研究了环境温度、运行负荷和润滑脂容量变化时滚动轴承内部温度的特征,并应用于现场223型滚子轴承的温度诊断技术中.     

弹流润滑悬挂式转子支承轴承轴向刚度的计算

以悬挂式转子的圆锥滚子支承轴承为研究对象,根据Hertz接触理论得出了沿圆锥滚子母线方向的弹性变形量表达式;根据弹性流体动力润滑的Dowson-Higginson油膜厚度公式得出了沿圆锥滚子母线的油膜厚度表达式;推导出考虑油膜厚度时计算圆锥滚子轴承轴向刚度的数学公式.并用一个实际算例说明,当轴向载荷不高的情况下,油膜的存在对轴承刚度影响较大,实际计算中不应忽略.     

高铁圆锥滚子轴承滚子与滚道间的接触分析

基于Hertz接触理论与滚子切片理论,对高铁圆锥滚子轴承中不同凸形的滚子与滚道间的接触问题进行了数值分析.建立了滚子-滚道接触应力与接触载荷计算模型,对CRH3型高铁用轴承进行实例分析,求解其在滚子母线方向上的应力与载荷分布,并计算对数曲线型滚子在满载情况下的最佳凸度量.结果表明:滚子的应力集中程度与所受载荷大小相关;滚子的对数曲线型只能减小并不能消除滚子的应力集中现象;滚子的最佳凸度量略小于理论凸度值.     

滚动轴承润滑脂成膜能力的实验研究

在相同的几何和运动条件下,用光干涉法研究了五种润滑脂的弹性流体动力润滑膜的成膜情况。给出了室温(24℃),轻载及充分供脂时这五种润滑脂的弹流膜厚随速度而变化的实验结果。     

双金属复合内圈滚动轴承接触特性分析

为解决圆柱滚子轴承在大载荷条件下易磨损的问题,设计了一种双层金属复合材料内圈圆柱滚子轴承.以复合内圈与滚子的接触为例,基于赫兹接触理论和波西涅斯克理论,给出了单个滚子与轴承内圈的最大接触应力.结合层复合材料力学模型,计算双层金属复合材料内圈等效弹性模量.建立内圈与单个滚子间接触模型,采用有限元仿真方法,探究不同材料厚度下的接触应力和弹性变形.通过接触摩擦试验,验证复合材料内圈在不同材料厚度下的接触宽度.结果表明:双层金属复合材料内圈轴承滚子与内圈接触变形增大,接触应力减小,可以有助于减少圆柱滚子轴承的磨损.     

三维弹性接触问题的边界元法

本文从弹性理论的基本方程出发给出了三维无摩擦弹性接触问题的边界积分方程及数值离散技术,并通过实例将本法的计算结果同理论解、实验结果和其它数值方法的结果进行了比较,表明该方法是非常有效的。     

大型四列圆锥滚动轴承载荷特性边界元法解析

二辊或四辊轧机的辊系，对工作辊四列圆锥轴承满寿可靠运行起至关重要甚至决定性作用。在轧制力或弯辊力下的轧辊弹性弯曲变形微尺度失控行为，致使四列圆锥轴承异常偏载。给出大型轧机四列圆锥滚子轴承三维载荷数值解法，定量描述圆锥轴承三维载荷分布特性，并以滚子载荷工况评估多列圆锥轴承的实际寿命，取代现有轧机设计理论中的总体轴承工况寿命评估法，具有重要的工程价值。     

偏歪斜滚子摩擦副的接触应力分析及凸度设计

根据静弹性接触理论,建立滚子与滚道同时存在偏斜和歪斜工况下的力学模型,并利用快速傅里叶变换(FFT)求解其弹性变形,用共轭梯度法求解接触应力.通过分析各种工况参数对接触应力分布的影响发现:歪斜角一定时,随着偏斜角的增大,"偏斜效应"和"边缘效应"均变得更加明显;偏斜角一定时,"歪斜效应"随着歪斜角的增大而逐渐明显,且偏斜角能减弱滚子与内滚道接触产生的"边缘效应",滚子则与外滚道接触产生更加严重的"偏斜效应"和"歪斜效应";随着滚子长径比的增加,滚子与滚道接触副产生的"偏斜效应"和"歪斜效应"逐渐明显.最后通过改变滚子凸度提出了一种综合考虑滚子偏、歪斜工况的凸度设计方法,以提高滚子轴承的抗偏、歪斜能力.     

三种润滑油性能对齿面接触强度的影响

利用圆柱滚子试件,在JP-BD1500型滚动接触疲劳试验机上,对法国壳牌油、N100和N68工业齿轮油进行接触疲劳和抗塑变对比实验;用弹性流理论计算表面间的润滑状态,并对试件表面的微观形貌进行观察;探讨了润滑油性能对齿面接触强度的影响。并提出了一种直观定量评价油的抗塑变能力的实验方法。     

链传动啮合冲击理论分析及有限元模拟

啮合冲击是引发链传动产生振动、噪声以及链条零部件发生疲劳损坏的主要原因,因此,精确地分析与计算啮合冲击载荷是进行轮齿强度计算以及链传动系统动力学研究的重要内容.为此,建立了链轮轮齿滚子间啮合冲击动力学模型,计算了啮合冲击力幅值;采用赫兹接触理论,对齿面接触应力进行了静态条件下的理论计算;建立了套筒滚子链传动系统有限元模型,采用三维弹性接触问题有限元分析方法,对轮齿滚子间的啮合冲击效应进行了精确模拟,分析了具有标准齿廓形状轮齿滚子瞬时啮合时,冲击载荷变化规律及应力分布情况.计算结果表明:在动态条件下轮齿滚子作为弹性体发生冲击接触时,接触区域变形并非理想的长方形区域;轮齿齿面的冲击接触力分布是不均匀的;在理论接触区域两侧冲击应力较大;在考虑了链轮齿形、间隙及弹性变形等多种影响因素的条件下,动态冲击载荷远大于静态条件下的理论计算值.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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