共查询到20条相似文献,搜索用时 312 毫秒
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为了研究表面粗糙度及热效应对非牛顿混合润滑的影响,基于平均流量模型,考虑表面粗糙度以及热效应,建立线接触非牛顿混合润滑模型。研究表面粗糙度对膜厚、膜厚比、平均摩擦因数、载荷比以及温度分布的影响,并与等温解进行比较。结果表明:随着表面粗糙度的增大,油膜温度逐渐升高,尤其是出口区与入口区的温升最为显著,且油膜温升越大,载荷比及平均摩擦因数越大,膜厚比越小;与等温解相比,热解的膜厚比及平均摩擦因数小,载荷比大;等温与热条件相比,中心膜厚与最小膜厚随表面粗糙度的变化趋势差异显著,说明热效应对混合润滑的影响不可忽略。 相似文献
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薄膜润滑中固—液相变的模拟 总被引:1,自引:0,他引:1
本文以分子动力学方法模拟了薄膜润滑中润滑剂的固液相变。模拟系统由两个平行的固体壁面和界于壁面间的流体分子构成。薄膜中流体分子的运动规律可由系统运动方程解得,再通过平均得到薄膜液体的宏观特性。计算结果表明,在薄膜润滑中润滑剂的一些性质会变成与膜厚有关的参量,一定条件下还会发生由壁面诱发的相变。薄膜中润滑剂的相变临界压力随膜厚的减小而降低,当相变压力低于系统给定压力时,润滑剂会发生固化。这种现象与薄膜中有序结构的发展规律有关。随着压力增加,流体分子的有序结构由壁面逐渐向薄膜中部发展,因此较厚的润滑膜需要较高的压力才能形成贯穿全膜的有序结构而产生相变。 相似文献
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考虑了橡胶轴承材料蠕变特性,建立了水润滑轴承的无限长线接触模型,基于Kelvin模型和三参量模型,对水润滑橡胶轴承进行了弹流润滑分析。通过这两种蠕变模型,分别得到了橡胶蠕变对润滑膜压力和膜厚的影响;分析比较了两种模型影响下的中心压力、中心膜厚和最小膜厚随时间的变化。结果表明,考虑橡胶轴承蠕变特性对润滑膜压力和膜厚的影响很大,在两种蠕变模型下,润滑膜的压力均随着蠕变时间变小,润滑膜厚随着蠕变时间变大,同时接触区不断增大并趋于稳定。中心压力随着蠕变时间逐渐增大并趋于稳定,最小膜厚随着蠕变时间先增加后减小到稳定值。蠕变稳定后,两种模型下的压力、膜厚均大于将橡胶轴承视为线弹性体的值,与之前工作对比,三参量固体模型比Kelvin模型更能描述橡胶轴承的润滑性能。 相似文献
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纳米薄膜润滑及其改性的分子动力学模拟 总被引:1,自引:0,他引:1
研究了纯正十三烷和含有摩尔分数为10%的多面体倍半硅氧烷材料T8H8的正十三烷两种润滑膜在不同剪切速率下的纳米薄膜润滑行为。首先建立了长链分子间的作用力模型,接着运用分子动力学模拟的方法得到了两种润滑膜分别在1 m/s、5 m/s、10 m/s和20 m/s四种不同剪切速率下所受到的平均剪应力以及沿着膜厚方向的速度、密度和平均温度分布,考察了一些特殊的物理现象。结果表明:分层和层间滑移现象在两种润滑膜的各种剪切速率下都会发生,是纳米薄膜润滑中的普遍现象;随着剪切速率的不断增加,两种润滑膜内部的温度都在不断升高。在各种剪切速率下,润滑膜中心层的温度总是达到最高值;T8H8加入到纯正十三烷中能显著降低润滑膜所受到的剪切应力和内部产生的温度,达到改善润滑剂润滑效果的作用。 相似文献
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The β-FeSi2 thin film has been applied in the research field of the solar cell,and the thickness of β-FeSi2 absorption layer was chosen through the experiments.However,Up to now neither the optimal thi... 相似文献
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The thickness of adsorbed molecular layers is the most critical factor in studying thin film lubrication, and is a key feature that distinguishes thin from thick film lubrication analysis. A method is presented that enables the adsorbed layer thickness to be calculated. This is based on adsorption theory and expressed in terms of molecular interaction energies. A continuous cross-gap viscosity model incorporating the layer thickness is introduced and used to calculate the load capacity and frictional characteristics of a simple bearing operating in the thin film regime. 相似文献
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薄膜润滑中双电层效应影响分析 总被引:4,自引:1,他引:3
根据Poisson—Boltzmann双电层理论,详细推导了润滑区中双电层产生的流动电场,并进一步建立了考虑双电层电粘度效应的薄膜润滑数学模型。然后,对润滑中双电层效应进行了数值分析,对不同的电粘度公式进行了比较,结果表明薄膜润滑中,双电层的电粘度效应使流体粘度显著增加,同时润滑膜厚也明显增加。 相似文献
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近年来,基于非晶铟镓锌氧化物的柔性光电薄膜晶体管在柔性显示、通信和探测等领域得到广泛应用。为提高柔性光电探测器的开关电流比和光谱灵敏度,文中基于SILVACO软件的ATLAS对柔性有源层非晶铟镓锌氧化物薄膜晶体管进行了模拟分析,研究在不同材料有源层厚度比情况下具有底栅电极结构的柔性光电器件的光电性能。分析结果表明,双有源层结构比单有源层结构薄膜晶体管有更好的电学性能,特别是在有源层结构厚度为40 nm的情况下,当铟锌氧(Indium-Zinc-Oxide,IZO)与铟镓锌氧(Indium-Gallium-Zinc-Oxide, IGZO)材料的厚度比为1:7 时,柔性光电器件具有最佳的开关电流比;在波长为300 nm的光照下入射光对光器件的关态电流增益影响最大,光电器件的积分灵敏度最高,说明其对紫外光较敏感,有望应用在军事通讯、空间科学、环境和生物细胞癌变监测等紫外光波段探测领域。 相似文献
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为了阐释空气静压导轨气膜间隙处在微小尺度所体现的特性,引入努森数(Kn),计算了不同工况下气膜内压力和不同气膜厚度下Kn数的变化关系。引入支撑区气膜分层假设,与分子动力学相结合,对气膜内不同流态层的刚度进行了实验和分析。通过ANSYS仿真和实验数据相结合得出了结论:气膜内稀薄效应的增强,可以一定程度上提高气浮支撑的静承载能力。气浮支撑的刚度特性和气膜内部分层情况有关:以分子碰撞运动为主的稀薄层主要起容性效应,实现分子间动量的传递和转化,因此该层所体现出来的刚度较差;以惯性力驱动的连续流层内部分子运动比较稳定,特别是在垂直方向不存在显著的动能和压力能之间的转化,因此该层的刚度特性较强。实验证明,气膜厚度在1~10 μm时,气膜的刚度先增大后减小,也间接论证了静压支撑的刚度特性主要由气膜内连续流层决定。 相似文献
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Optical interferometry has proved to be a valuable experimental tool in the study of elastohydrodynamic lubrication (EHD). It is a technique that gives detailed information on the lubricant film distribution within the contact; however, the sensitivity is limited and it is only recently, with the development of the spacer layer optical technique, that the study of the thin film lubrication regime has been possible. The limitation of the spacer layer technique is that generally only one measurement is taken from the center of the contact. The next logical step in the development of this technique is, therefore, a system that combines the mapping capabilities of the original optical method with the thin film capabilities of the spacer layer approach. This paper describes the development of a contact mapping technique that uses the spacer layer approach to visualize, and measure, thin lubricant films in concentrated contacts. The development of the technique is described and its application to both static and moving contacts reported. Thin EHD films (down to 10 nm) have been measured and mapped. 相似文献
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Modeling and analysis of interfacial electro-kinetic effects on thin film lubrication 总被引:1,自引:0,他引:1
At the interface between a solid and a following liquid, charge migration within the electric double layer causes an electro-viscous force to develop which manifests itself as an enhanced fluid viscosity. Based on the Poisson–Boltzmann equation, a new mathematical model of the electro-viscosity is developed. Numerical analysis is carried out taking into account the influence of the electric double layer on thin film lubrication. Analysis results show that the electro-viscosity leads to a significant increase in the film thickness in the thin film regime (below 100 nm). 相似文献
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Spin‐coated epoxy resin embedding technique enables facile SEM/FIB thickness determination of porous metal oxide ultra‐thin films 下载免费PDF全文
A facile nonsubjective method was designed to measure porous nonconductive iron oxide film thickness using a combination of a focused ion beam (FIB) and scanning electron microscopy. Iron oxide films are inherently nonconductive and porous, therefore the objective of this investigation was to optimize a methodology that would increase the conductivity of the film to facilitate high resolution imaging with a scanning electron microscopy and to preserve the porous nature of the film that could potentially be damaged by the energy of the FIB. Sputter coating the sample with a thin layer of iridium before creating the cross section with the FIB decreased sample charging and drifting, but differentiating the iron layer from the iridium coating with backscattered electron imaging was not definitive, making accurate assumptions of the delineation between the two metals difficult. Moreover, the porous nature of the film was lost due to beam damage following the FIB process. A thin layer plastication technique was therefore used to embed the porous film in epoxy resin that would provide support for the film during the FIB process. However, the thickness of the resin created using conventional thin layer plastication processing varied across the sample, making the measuring process only possible in areas where the resin layer was at its thinnest. Such variation required navigating the area for ideal milling areas, which increased the subjectivity of the process. We present a method to create uniform thin resin layers, of controlled thickness, that are ideal for quantifying the thickness of porous nonconductive films with FIB/scanning electron microscopy. 相似文献