纳米尺度接触过程力学特性实验研究

利用纳米压痕仪进行纳米尺度接触力学特性实验研究,通过金刚石探针与单晶硅试件接触作用,获得不同载荷、不同接触深度条件下的接触压入和脱离接触的位移-载荷曲线,并利用原子力显微镜对接触区域扫描,获得接触区域AFM三维形貌图。研究表明,在不同载荷条件下接触压入,随着载荷的增大,接触深度也随之增大;在不同深度条件下接触压入,随着接触深度的增大,接触作用力也随之增大。脱离接触的时候,接触区有弹性恢复,但有残余变形,接触区域表现出了塑性变形,压痕附近区域没有裂纹情况出现,载荷或接触深度越大,接触塑性变形越明显。此外,在不同载荷、不同接触深度条件下,接触区的压痕硬度和弹性模量相应有不同值,接触压痕硬度值和弹性模量值均有一定变化。     

蹦极弹性绳试验台连杆机构的遗传算法尺度综合

为了给蹦极绳型式试验提供一种试验设备,设计了一种试验台的原型,并分析了试验原理。提出了该装置的一种基于遗传算法的尺度综合的方法,并给出了计算结果。通过优化计算表明,该方法得到的参数能较好的满足试验台的设计要求。     

基于量子遗传算法的多峰函数优化研究

针对标准遗传算法在多峰函数寻优中出现的局部收敛性及精度不高等问题,提出了一种基于量子遗传算法的多峰函数优化算法.该算法融合了量子计算和遗传算法的思想,通过量子比特编码和量子旋转门调整策略更新种群.仿真结果表明该优化算法收敛速度快,能跳出局部最优,在多峰函数寻优中具有有效性和可行性.     

基于实数量子遗传算法的行星轮减速器优化设计

提出了一种基于实数编码的量子遗传算法,其核心是用实数对量子比特进行编码.通过求解行星轮减速器的体积优化问题,表明实数量了遗传算法比传统遗传算法具有更优的搜索稳定性.     

基于量子遗传算法的轴向柱塞泵故障特征选择

为了进一步减少特征维数、缩短运算时间、提高分类正确率等,提出了一种基于量子遗传算法的轴向柱塞泵故障特征选择方法,该方法采用量子位进行染色体编码,利用量子门更新种群。首先,对轴向柱塞泵振动信号进行小波包变换,提取出原始信号和各个小波包系数的统计特征;然后,利用量子遗传算法从原始特征集中选择出最优特征集;最后,以神经网络为分类器(其输入为最优特征集),对故障进行诊断与识别。利用该方法对轴向柱塞泵正常、缸体与配流盘磨损和柱塞滑履松动三种状态的特征集进行选择,试验结果表明,与普通遗传算法相比,量子遗传算法可以更有效地减少特征维数,提高分类正确率。     

基于量子遗传算法的拆卸序列规划

拆卸序列规划是再制造过程中的重要环节之一。为了高效求解拆卸序列规划问题,利用有向图建立了拆卸模型,并用优先矩阵描述了该模型。在此基础上,首次提出了一种基于量子遗传算法求解拆卸序列规划的方法,扩展了量子遗传算法应用领域,也提高了拆卸序列规划的效率。最后,用一个工程实例验证了方法的可行性。     

一种求解Job-Shop调度问题的量子遗传算法

提出了一种基于操作方式进行编码和解码的量子遗传算法,并将其用于求解一种典型的NP-hard组合优化问题即Job-Shop调度问题.该算法采用量子比特方式构造染色体,增加了算法的种群多样性和计算并行性;采用量子旋转门操作实现种群进化,有效地提高了算法的收敛速度.用基准调度问题实例对该算法进行的测试结果表明:该量子遗传算法与改进的遗传算法相比较有更好的优化性能.     

纳米尺度下流体的流变及尺度效应

应用表面力仪研究了流体在纳米尺度下的流变及尺度效应。试验发现，体相状态时表现为典型牛顿流体的16 烷，在纳米膜厚状态下，出现了等效粘度随切应变速率的增大而减小的剪切稀化现象，并且等效粘度依赖于振动剪切的频率。随着膜厚从宏观量级进入到纳米量级，流体的特性具有了显著的膜厚相关性，其表现为等效粘度明显增大，流体出现了弹性特征，摩擦力表现出复杂的非牛顿特性。其他流体也表现出类似的特性，这些流变特性的改变，说明纳米尺度下流体具有与体相状态完全不同的特性。     

基于量子遗传算法的WSN定位算法

针对无线传感网络由于位置信息等原因造成的定位误差较大、精度不高等问题,在继承DVHop定位算法优点的基础上对其进行改进,提出了一种基于量子遗传算法的无线传感器网络节点定位技术。将其应用于DV—Hop算法的第3阶段,对节点的位置进行校正,利用量子遗传算法求解模型的最优解,从而得到未知节点的最优估计位置。改进的DV—Hop定位算法与原算法相比,改进的算法能够改善定位覆盖率低的问题,在锚节点比例较低的情况下有更高的定位精度。     

Nanoscale Lubricant with Strongly Bonded Phase and Mobile Phase

The best tribological properties can be obtained in a film that contains both bonded and mobile phases, and thus the ratio of the bonded phase to the mobile phase, the bonded ratio, is a critical factor for the lifetime of the mechanical components. In the present study, we deposited a mixed lubricant, which consists of a strongly bonded lubricant phase and a mobile lubricant phase, on a carbon overcoat. Islands of FDTS (perfluorodecyltrichlorosilane) SAM (self-assembled monolayer) were introduced as a strongly bonded lubricant phase and Fomblin Z03 lubricant as a mobile phase. The friction and durability properties of 2.5-in magnetic disks coated with 15 Å thick mixed lubricants were investigated using a ball-on-disk tribotester and compared with disks coated with 15 Å Zdol lubricants. Because the contact area of the ball increases with the bonded ratio, the friction coefficient of the disk coated with the mixed lubricant increases linearly with the bonded ratio over a range of about 25–100%. On the other hand, the friction coefficient of the disk coated with Zdol decreases with increasing bonded ratio. The mixed lubricant exhibits superior wear properties compared to Zdol. This may occur because the FDTS networks act as a barrier against the displacement of the mobile Z03 molecules, and the mobility of Z03 molecules is higher than that of Zdol molecules, which allows Z03 to replenish into the lubricant-depleted area at a higher rate.     

Stability Analysis of Ultra-Thin Lubricant Films with Chain-End Functional Groups

The thermodynamic stability of ultra-thin perfluoropolyether (PFPE) films is examined. The model used in this paper incorporates a layered structure due to polar interaction at the endgroups and provides the stability criteria as a function of film thickness, the surface/interfacial energies of PFPEs and substrates, and molecular weight. The surface energies of PFPEs were obtained from measured contact angles and separated into non-polar and polar components using Fowkes' method. The stability of PFPE films is examined via a diagram constructed from the measured surface energies of PFPEs and hydrogenated carbon substrate.     

固体润滑材料内部因素对摩擦性能影响的分析表征

采用x-射线衍射仪、扫描电镜、大型偏光显微镜、差热和失重分析仪等现代仪器对聚四氟乙烯（PTFE）基固体润滑剂材料的成分、组织结构和组分的物理化学性能及力学性能等进行了表征及分析。结果表明,PTFE、石墨、二硫化钼及铜粉颗粒尺寸均基本保持在30 μm内;碳纤维直径较均匀,基本保持在8～10μm,但长度不均匀;加入填料的固体润滑剂比纯PTFE吸水率高、熔融温度及分解温度低,且会引起氧化分解反应;吸水率大小顺序为：石墨＞碳纤维＞二硫化钼＞PTFE≥铜粉;PTFE基复合材料的表面硬度基本是随着填料的加入量的增加而增加的;在PTFE树脂中加入无机填料均可明显提高其抗压强度,但并不是加入量越多,抗压强度提高越明显。     

ADAMS动力学仿真算法及参数设置分析

首先,介绍了ADAMS中的机械系统动力学方程;其次,分析了ADAMS中GISTIFF刚性积分算法;然后,对ADAMS动力学仿真参数的设置进行了总结;最后,指出了本文的意义和进一步研究的方向.     

润滑油抗乳化性综合评价方法研究

针对国标GB/T 7305—2003对润滑油抗乳化性评价方法中油水比设定及乳化工况与实际使用情况相差较大的问题,考虑到润滑油抗乳化性的实际影响因素,通过改变油水比、乳化工况,观测4种常用润滑油的油水乳状液外观与界面情况,测定分水率、分水速度、水相含油量及油相含水量,评价润滑油的抗乳化性。结果表明,油水比上升时,润滑油乳状液的分水速度和分水率均下降,水相含油量和油相含水量均上升,在高油水比时变化更加明显。因而随着油水比的增加,润滑油的抗乳化性能逐渐下降,不同润滑油乳状液间的抗乳化性能差距变大。基于上述分析,提出一套润滑油抗乳化性能综合评价方法,该方法在国标GB/T 7305—2003评价方法基础上,在实际工况油水比下,增加分水率、分水速度、水相含油量、油相含水量的定量评价,可完全反映出润滑油在实际使用工况下的抗乳化性。     

Measurement of the Rheology of Lubricant Films Within Elastohydrodynamic Contacts

There is growing need for a reliable model of the rheological response of lubricants in elastohydrodynamic (EHD) contacts, not only to predict behaviour in full-film EHD conditions, but also for use in modelling mixed-film lubrication. One barrier to developing such a model is that measurements of friction actually represent averaged values over the whole, lubricated contact under study. However the fluid film conditions of temperature, pressure and strain rate generally vary over such contacts, which makes it difficult to determine constitutive shear-stress equations from friction measurements. This paper examines the various different techniques used to study the origins of EHD friction and the underlying film rheology. It then describes and applies a technique for obtaining the temperature rise maps of both solid surfaces in a rolling-sliding EHD contacts and thus shear-stress and friction maps. The work shows that the shear stress of the traction fluid studied increases approximately linearly with pressure and decreases approximately linearly with temperature in the high-pressure central region of EHD contacts.     

Effects of Nanoscale Surface Texturing on Self-Healing of Boundary Lubricant Film via Lateral Flow

Surface texturing of silicon substrates with nanowells can change the lubricious performance of cationic polymer lubricant (CPL), a bound-and-mobile lubricant consisting of a polydimethylsiloxane (PDMS) backbone with covalently bonded quaternary ammonium iodide cations. The filled nanowell reservoirs enhance self-healing within the contact track since they can readily provide CPL to near-by regions. However, once this initial reservoir is completely consumed and depleted, the empty nanowells interfere with long-distance lateral flow process since they act as a reservoir that needs to be filled during the flow.     

分散剂对有机粘土润滑油摩擦学性能的影响

以30#机械油为基础油,以0.4%季铵盐修饰有机粘土为添加剂,5%低碱值合成磺酸钙和5%聚异丁烯双丁二酰亚胺为分散剂,制备了几种分散剂优化的有机粘土润滑油。采用OPTIEN2120型紫外/可见分光光度计对分散剂的分散效果进行了检测;在M-200和MS-800型摩擦磨损试验机上,分别对不同分散剂作用下的有机粘土润滑油的减摩抗磨性能和承载能力进行了测试。分散效果检测表明分散剂可有效控制粘土微粒的粒径,阻止粘土微粒的团聚,使得粘土微粒在基础油中有良好的分散稳定性。摩擦磨损试验表明:分散剂能改进有机粘土润滑油的摩擦学性能,其中2.5%低碱值合成磺酸钙与2.5%聚异丁烯双丁二酰亚胺分散剂复配使用时有机粘土润滑油的摩擦学性能最佳;分散剂的加入在一定程度上能够提高有机粘土润滑油的承载能力。     

Molecular Dynamics Simulation on the Aggregation of Lubricant Oxidation Products

The aggregation phenomenon of lubricant oxidation products, fatty acids, fatty alcohols, aliphatic aldehydes and aliphatic ketones in base oil, was probed by molecular dynamics (MD) simulation. The results show that there are aggregates formed in fatty acids or fatty alcohols, and that the aggregation does not occur in aliphatic aldehydes and aliphatic ketones in single component models. Fatty acids or fatty alcohols are connected by hydrogen bonds in the form of dimers or multimers. The hydrogen bond can be formed at a higher temperature in fatty acids, but not in fatty alcohols. In the mixture models, there are dimers and/or multimers constructed by different molecules of lubricant oxidation products, and the multimers have a chain or a ring structure. The number of molecules involved in the formation of aggregates decreases with the increase of temperature. The opportunity to construct hydrogen bonds rises with the increasing concentration of oxidation products. Obvious aggregation occurs at 25 and 100 °C in conditions of high concentration, while it happens only at 25 °C with lower concentration. It is easier for fatty acids and fatty alcohols to form hydrogen bonds and the formed hydrogen bonds are more stable, which result in a higher concentration of fatty acids and fatty alcohols in the aggregates. Fatty acids and fatty alcohols are possibly more significant in the formation of aggregates and it may be beneficial to prevent the aggregation by controlling the concentration of them in lubricating oil.     

坡缕石载铜复合纳米润滑添加剂的制备及摩擦学性能研究

使用化学还原法制备坡缕石载铜复合纳米颗粒,以铸铁HT200作为摩擦副,采用MMU-10G摩擦磨损试验机研究该纳米颗粒作为润滑添加剂的摩擦学行为,使用EPMA-1600电子探针、金相显微镜、Genesis能谱仪进行试样磨损面形貌观察和组成元素分析。实验结果表明:该纳米复合颗粒作为润滑添加剂具有优异的减摩效果和良好的抗磨性能,与基础油150N相比,平均摩擦因数下降66.2%,对应的摩擦副试件磨损失重减少80.9%,在试件表面生成由纳米坡缕石和纳米铜共同组成的自修复膜。