高速角接触球轴承变形和接触角的数值分析与求解

文章在Hertz接触理论的基础上,应用Harris滚动轴承分析理论,针对球轴承,分析了其内部变形、接触角及其求解方法;并以角接触球轴承为例,应用哈姆罗克Hertz接触的简化解,对角接触球轴承内部变形进行了数值分析与计算,以便于高速轴承和轴系的量化分析,为球轴承的设计计算以及主轴的设计提供了重要参数。     

不同载荷下的球轴承内部接触热阻计算

针对球轴承滚动球体与内、外滚道之间的不完全接触而引起的接触热阻,结合半空间椭球坐标系拉普拉斯温度分布方程,提出了滚动球体与内、外滚道之间接触热阻的理论计算方法.以赫兹接触理论为依据,研究了轴承内部载荷分布和椭圆接触区域参数的确定方法.分析了不同载荷对轴承内部接触热阻的影响.高速进给系统平台的实验结果表明理论值和实验测试值的最大误差仅为4.62％,该方法为不同载荷条件下球轴承内部接触热阻的解析计算提供了一种有效方法.     

高速小型复合分子泵的轴承温度场分析

高速小型复合分子泵中的轴承为混合陶瓷球轴承,轴承在工作过程中由于摩擦力矩会产生大量的热量,影响分子泵的正常工作。采用Palmgren发热量计算模型给出了具体工况下陶瓷球轴承生热量的计算公式,应用有限元分析软件ANSYS Workbench得到了轴承的温度场分布,为陶瓷球轴承的润滑和延寿奠定基础。     

轿车轮毂轴承疲劳寿命的计算与分析

基于滚动轴承动力学分析理论,建立了双列角接触球轴承内部元件间相互作用力数学模型。利用双列滚动轴承寿命计算法,建立轿车轮毂轴承寿命计算模型。采用精细积分法和预估-校正Adams-BashforthMoulton多步相结合的算法对双列角接触球轴承作用力模型进行求解,分析轮毂轴承轴向预紧量和轮毂偏移量对轴承寿命的影响。分析结果表明:轴向预紧量的增大和轮毂偏移量由负值变化到正值均会使轴承寿命呈现先增大后减小的趋势,且存在一组最佳轴向预紧量与轮毂偏移量使得轮毂轴承寿命最大。     

计入粗糙度的深沟球轴承弹塑性接触性能分析

为揭示表面粗糙度对深沟球轴承弹塑性接触性能的影响,根据该轴承的载荷分布,把滚动体与内滚道接触转变为二次型函数极值问题,并建立考虑表面粗糙度的该轴承弹塑性接触模型,运用半解析法对该模型进行求解,获得了计入表面粗糙度影响的深沟球轴承弹塑性接触性能。数值结果表明:表面粗糙度会使内滚道宽度方向两端处的局部压力减小,同时使内滚道接触压力、von Mises应力、残余应力和残余变形的幅值较光滑情况时增大;同时表面粗糙度导致深沟球轴承中内滚道接触压力和残余变形分布发生波动,易使内滚道次表面产生应力集中,进而影响轴承整体使用寿命。     

钢丝滚道球轴承设计中的接触问题研究

本章主要应用弹性接触理论以及赫兹接触理论对钢丝滚道球轴承滚动体与钢丝滚道的点接触问题进行分析,得出接触区载荷与变形的关系,根据实际需要进行简化,进而计算出接触区各主要参数,然后通过ANSYS对钢丝滚道球轴承点接触问题进行建模与仿真分析,得到接触压力和各向应力分布云图。     

机械轴承工作状态的ANSYS仿真研究

钢丝滚道球轴承是机械结构中常见的轴承方式之一,为了更好的了解其工作性能,应用弹性接触理论,对机械轴承的工作状态进行ANSYS仿真分析。通过对钢丝滚道球轴承点接触问题进行建模与仿真分析,得到接触压力和各向应力分布的状态。     

考虑热膨胀影响的脂润滑高速角接触球轴承热特性分析

高速机床主轴轴承常采用脂润滑角接触球轴承,其在高速运转下过高的温度升高会严重影响轴承工作精度,导致精度丧失和使用寿命降低.该文建立了包含热膨胀影响因素的角接触球轴承载荷平衡方程,针对脂润滑条件,生热计算应用基于局部热源的局部法,热分析采用多节点热网络法,理论计算得到了热网络中各节点温度.在此基础上分析了热膨胀对轴承动态...     

深沟球轴承动态有限元数字仿真

基于动态接触力学和显式动力学有限元算法,采用三维实体单元建立参数化的深沟球轴承三维有限元模型.利用有限元软件LS-DYNA和自适应网格技术对深沟球轴承的工作运动过程进行了数值模拟,得出了轴承内外圈、滚珠、保持架之间的接触应力、应变的变化情况及接触过程中的压力分布情况.并将计算结果与赫兹理论计算结果进行比较,验证了动态有限元仿真的合理性.在此基础上,综合考虑了轴承原始制造误差、转速、载荷等不同工况对轴承动态性能的影响,为轴承的疲劳强度计算和动态优化设计提供了可靠的理论依据.     

四点接触球转盘轴承的静刚度计算

刚度是滚动轴承的一项重要性能。以Hertz弹性接触理论为基础,采用数值方法计算了转盘轴承在单一和复合载荷下的刚度,此法比传统的算法求解精度高。首先,建立了单排四点接触球转盘轴承的静力学模型,然后导出了转盘轴承的刚度计算公式,开发了计算程序并进行求解。最后用实例进行了计算分析,得出了转盘轴承在不同载荷下的刚度,并分析了转盘轴承结构参数对刚度的影响。     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.