虎克万向节节叉轴承滚针的凸度设计

虎克万向节十字轴节叉轴承的滚针凸度决定了滚针与滚道间接触压力的分布状况,是影响万向节性能和寿命的主要因素之一．为改善万向节的性能,文中基于Lundberg对数凸型方程和三维有限长弹性接触问题的数值计算,分析了轴承结构参数对接触压力分布的影响,提出滚针凸度量设计时必须考虑滚针倒角半径和越程槽宽度的影响,并给出了相应的数值计算方法．使用该方法设计的滚针轴承,可以避免接触压力分布出现“边缘效应”,也可避免在接触区域发生部分应力集中,提高了万向节的性能和使用寿命．     

对数凸度设计在十字万向传动轴中的应用

十字万向传动轴被广泛地应用在各类机械传动中,十字轴轴承是其重要的部件．轴承滚针的凸度设计,决定了滚动体与滚道间的接触压力分布,影响其性能和寿命．根据轴承结构对接触压力分布的影响,在滚针凸度设计时必须考虑滚针倒角半径和越程槽宽度的因素,并应用相应的数值计算方法．结果表明,使用这种方法设计的滚针轴承,其接触压力分布不会出现“边缘效应”,也不会在接触的中心部分出现应力集中。     

滚动轴承滚针凸度量设计的可视化计算

首先介绍了三维有限长弹性接触问题的数值方法和实体套筒滚针轴承中的越程槽结构因素对对数凸型滚针接触压力分布的影响,利用可用于多种结构形式的滚动轴承滚针凸度设计方法,在Windows操作系统中,基于Visual Basic 6．0面向对象的程序设计平台,开发出考虑越程糟时滚针凸度量设计的可视化计算软件。     

滚针凸度修型对滚动轴承应力分析的影响

针对滚针凸度修型及修型半径对滚动轴承应力分布的影响，课题组以KIRD234021型滚动轴承为研究对象，分别建立滚子无凸度和相切圆弧修型两种模型，当修型R弧半径在300～1000mm范围内时，分别计算其轴承内圈滚道应力。研究结果表明：当滚子为无凸度修型时，内圈滚道最大接触应力为6404MPa，此区域亦为形变及磨损最严重处，其数值超过材料热处理后的许用接触应力4000MPa，极易导致轴承滚子及滚道产生点蚀及剥落进而失效；当滚子为相切圆弧修型、直母线L为5mm及R弧为300～800mm时，滚道最大接触应力普遍较低，此时对应滚针凸度范围为0.002～0.006mm。     

轧辊偏移条件下六辊轧机的板形调控特性

为提高冷轧带钢六辊轧机辊系的稳定性,目前常采用轧辊偏移方法.本文通过ABAQUS有限元软件建立辊系-轧件一体化耦合模型,对不同轧辊偏移辊系进行受力分析,揭示了不同轧辊偏移条件对六辊轧机板形调控特性的影响规律.结果表明,中间辊正向偏移轧制时,工作辊弯辊力对二次凸度调控功效最好,对四次凸度影响较大;在四种偏移方式条件下,中间辊弯辊力在0~300 kN范围内对带钢二、四次凸度调控功效基本相同;中间辊正向偏移轧制时,中间辊弯辊力在300~500 kN范围内对带钢二次凸度调控功效最好;工作辊正向偏移轧制时,中间辊弯辊力对四次凸度影响较大;不同轧辊偏移条件下中间辊窜辊对带钢二次凸度调控趋势基本相同,且负窜辊对二次凸度的调控功效优于正窜辊,工作辊正、反向偏移轧制条件下中间辊窜辊对四次凸度影响较大.     

四辊轧机轧制工艺参数对工作辊有载辊缝凸度的影响

利用在ABAQUS下建立的二维变厚度等效模型,分析静态下轧制力、弯辊力、工作辊窜辊量对有载辊缝凸度的影响.结果显示,轧制力对辊缝凸度的影响大于弯辊力对辊缝凸度的影响,轧制力、弯辊力波动对辊缝凸度的影响是显著的,窜辊量波动对辊缝凸度的影响是微小的.     

先进变凸度工作辊辊形及其控制特性

跟踪某2250 mm热轧生产线CVC辊形实际窜辊数据发现,连续变凸度(CVC)辊形常窜到两端极限位置.分析表明,CVC辊形的二次凸度调控能力随带钢宽度减小而呈二次方下降趋势,表现出对较窄带钢凸度控制能力的明显不足.Smart-Crown辊形也存在同样问题.提出一种新的先进变凸度(AVC)工作辊辊形曲线,其二次和四次凸度与窜辊量呈线性关系,且随着四次凸度控制能力的增大,二次凸度控制能力随带钢宽度的变化明显放缓,有助于提高宽带钢或超宽带钢轧机对不同宽度带钢的板形控制能力.     

CSP热轧CVC工作辊凸度范围的分析及选择

为更好地发挥CVC工作辊凸度调控能力,保证带钢板形质量,现场跟踪测试某CSP热轧生产线CVC工作辊实际窜辊情况,发现不同机架CVC工作辊辊形在使用过程中表现出窜辊形式的多样性,并反映出凸度控制能力不合适等问题.在对热轧不同机架的板形控制特点、热轧工作辊磨损对凸度调控能力的影响、CSP各机架不同的弯辊调控功效以及CSP大压下率的特点进行分析研究的基础上,提出了CSP热轧F1～F7机架从强到弱的CVC凸度控制能力选择原则,并相应给出了正态分布、抛物线分布、均匀往复窜辊三种不同的窜辊策略.     

精密轧机的辊型电磁调控工艺参数

为了实现微尺度辊缝形状调节,提出了辊型电磁调控技术,并自行设计制造了φ270 mm×300 mm辊型电磁调控实验平台.通过电磁-热-力耦合数理建模,并对比分析相同工况实验和仿真结果,发现两者结果十分接近,模型可靠.在此基础上,分析了不同等效电流密度和频率下轧辊凸度及轧辊凸度增长速率随加热时间的变化规律,给出了等效电流密度、频率、加热时间对辊型曲线的影响,并从避免电磁棒局部温度过高及便于轧辊凸度调节出发,给出了合理的工艺参数.     

金属模型与变形模型耦合计算热轧板凸度

介绍了一种热轧板凸度计算方法，即用金属模型与辊系变形模型耦合计算方法，计算中充分考虑了轧辊磨损及轧辊热凸度对热轧板凸度的影响，计算结果与某热轧生产线板凸度实测值吻合较好。     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has