摩擦改进剂对改善燃油经济性的影响研究

采用四球机试验,考察了钼胺化合物、二烷基二硫代氨基甲酸钼、无灰型摩擦改进剂与摩擦因数的关系以及它们之间的复配作用。结果表明：摩擦改进剂（FM）降低摩擦因数的效果与其化学结构有关;加入量提高,摩擦因数的改善效果明显;不同化学结构的摩擦改进剂复配使用,可以减低整个温度区的摩擦因数。     

重载铁路轮轨摩擦改进剂作用效果仿真研究

建立了某重载货车的车辆-轨道系统动力学模型,仿真分析了在轨侧涂油、轨顶涂摩擦改进剂和全面摩擦控制三种摩擦控制模式下车辆通过具有标准廓形和磨耗后廓形钢轨的曲线时的动力学性能和磨耗特性.研究结果表明,只对高轨轨侧进行润滑会使车辆通过小半径曲线的脱轨系数和横向力增大,而对两侧轨顶进行摩擦控制可以减小脱轨系数和横向力,摩擦改进...     

黏度指数改进剂对基础油性能的影响

用凝胶色谱测定乙丙共聚物(OCP)和氢化苯乙烯异戊二烯(SDC)黏度指数改进剂的分子量和分散度,用运动黏度测定法、高温高剪切表观黏度测定法测定OCP和SDC在4类基础油中的运动黏度和高温高剪切表观黏度,用柴油喷嘴测定法测定其100℃下的剪切稳定性,用冷启动模拟机法测定其-15℃与-20℃的低温动力黏度。结果表明:SDC分子量小于OCP,但分散度大于OCP,在相同基础油中其黏温性能、剪切稳定性优于OCP类;在4类基础油中,OCP和SDC的黏温特性表现为Ⅳ类Ⅲ类Ⅰ类,稠化特性表现为Ⅳ类Ⅰ类Ⅲ类Ⅱ类,剪切稳定性表现为Ⅳ类Ⅲ类Ⅱ类Ⅰ类;OCP和SDC稠化油的-15℃以及-20℃的低温动力黏度与基础油相当。     

拉深润滑剂的摩擦特性及其影响因素

本文采用自行设计的探地法测定摩擦系数，模拟板粒拉深变形条件下所测得的润滑剂润滑性能与传统的测试方法进行比较，能起初的反应塑料为形工况条件，其结果与生产实际情况十分吻合。     

横向振动状态下水润滑轴承摩擦动力学特性

低速重载等极端工况下摩擦诱导异常振动会极大地影响舰船推进轴系中水润滑轴承的稳定运转。针对水润滑轴承开展考虑横向振动的摩擦动力学性能研究,建立受横向振动效应影响的水润滑轴承混合润滑和流体动压润滑模型,分析2种状态下轴承的振动特性;通过将轴颈平衡位置下的坐标代入轴承横向振动模型中,得到轴颈的扰动量,研究不同激励幅值对轴承摩擦力的影响规律,探明弹性变形条件下水润滑轴承的摩擦诱导振动机制。结果表明：当轴承出现接触,横向振动对轴承的摩擦力影响较显著,将导致轴承摩擦力呈现非线性变化。研究结果为评估横向振动对摩擦力的影响程度、揭示轴承摩擦振动机制提供支撑。     

磨屑对润滑油摩擦性能的影响

通过实验和模拟研究磨粒对润滑油摩擦性能的影响。首先通过微纳米压/划痕试验测量含磨屑润滑油的摩擦因数。同时,建立边界润滑体系模型,采用分子动力学方法模拟含磨屑润滑油膜在不同载荷下沿膜厚方向的压缩率和密度分布;对体系的上下固体壁面施加方向相反的剪切速度,计算出壁面原子的应力、摩擦力、正压力和摩擦因数;分析不同粒径磨屑的动态行为特征;通过减少润滑油分子数量,探究乏油工况下含磨屑润滑体系的摩擦性能。结果表明,润滑体系摩擦因数的模拟值与试验值一致;磨屑的存在会降低油膜的压缩率,同时在高载下磨屑的存在会对油膜的分层产生破坏,影响磨屑附近的密度分布;含小粒径磨屑的润滑体系的摩擦因数比含大粒径磨屑的润滑体系的小,表明磨粒聚集长大现象会恶化润滑油的润滑性能;磨屑在剪切过程中同时存在滚动和滑动,含小粒径磨屑的润滑体系剪切过程中表现出波动幅度更大的角速度;随着载荷的增大,磨屑角速度减小,波动幅度降低;在乏油工况下,磨屑会在剪切过程中出现变形破碎现象。     

一种二甲醚专用润滑性改进剂的性能研究

采用四球机和高频往复试验机研究了一种二甲醚(DME)专用润滑性改进剂在不同基础试验液体中的润滑特性,考察了其与醚的互溶性能及对金属的腐蚀性能,并与其它润滑性改进剂进行了对比,从而为DME发动机选择合适的燃料润滑改进剂提供了依据。结果表明:该DME专用润滑性改进剂添加量少,润滑效果显著,与DME相容性好,没有腐蚀性。     

铰接系统减振器对虚拟轨道车辆动力学性能的影响

虚拟轨道车辆作为新型轨道交通,由于多节编组结构导致车辆自由度较多,可能会出现甩尾、横摆、折叠等不稳定现象,影响车辆行驶稳定性和平稳性。虚拟轨道车辆通过铰接系统进行连接,铰接系统阻尼较小,车辆易出现跑偏、失稳等情况,阻尼较大,则会降低列车的灵活性。基于某三模块六轴虚拟轨道车辆实际参数,建立车辆系统动力学模型,选择直线、换车道以及1/4圆曲线等典型工况,通过联合仿真等方法分析铰接阻尼对车辆动力学性能的影响。研究结果表明：直线工况下,增大阻尼系数能够有效抑制车辆的横摆角加速度,提高车辆的横向平稳性;在B级路谱、70 km/h工况下,阻尼系数为107N?s/m时,横向平稳性相比未安装铰接减振器降低14.1%,但对车辆垂向平稳性影响较小。换车道工况,阻尼系数过大或过小均会使列车的横向稳定性恶化,合理的阻尼系数将提高车辆的横摆阻尼比,减小车辆间的横向摆振,从而控制后部放大系数和轨迹偏移量;阻尼系数为107N?s/m时,后部放大系数显著减小,且轨迹偏移量由0.724 m降至0.511 m,减小29.4%。1/4圆曲线工况,增设铰接系统减振器将降低车辆的曲线通过性能,当阻尼系数为107N?s/m时,转...     

Effect of Friction Modifier on Rolling Contact Fatigue and Wear of Wheel and Rail Materials

In this study, the effects of a friction modifier (FM) on wear and rolling contact fatigue were investigated by twin-disc testing under various conditions. It was found that the contact fatigue damage occurred on the rail specimen under the FM condition and the water condition. The test under FM condition was performed under three different spraying times: 0.2, 0.5, and 1.0 s. The progress of contact fatigue damage severely increases at a spraying time of 0.2 s. Contact fatigue damage under the FM condition occurred faster than that under the water condition. Results show that the friction modifier induced a mixed condition that exists at the same time as the wet condition and the dry condition. Cracks were initiated by the traction force due to the friction of the dry condition and the crack growth rate became faster due to the fluid entrapment mechanism under the wet condition. Therefore, the amount of FM should be evaluted to avoid severe contact fatigue damage.     

Influence of Organic Friction Modifier on Liquid Slip: A New Mechanism of Organic Friction Modifier Action

Recent work using a number of experimental techniques has shown that simple Newtonian liquids can slip against very smooth, lyophobic surfaces. Most previous work has examined lyophobic surfaces produced by forming self-assembled monolayers on smooth substrates. However it has also been shown that octadecanoic (stearic) acid solution in hydrocarbon can promote slip of the liquid against smooth surfaces. This raises the intriguing possibility that one mechanism of action of organic friction modifier additives may be to promote slip in hydrodynamic contacts and thus reduce friction. To test this conjecture, experiments have been carried using a low-load, hydrodynamic friction tester in which a glass cylinder is loaded against a very smooth sapphire flat which has been previously immersed in stearic acid solution. The contact is supplied with a solution of stearic acid in hexadecane and the glass cylinder is rotated at a speed sufficient to generate a full hydrodynamic film. It is found that this system gives significantly lower friction than when using hexadecane alone or when the sapphire is slightly roughened. The results are consistent with the occurrence of liquid slip at the sapphire surface.     

有机无灰减摩剂对流体动压润滑减摩性能影响机制

有机无灰减摩剂能减低流体动压润滑摩擦因数,对提升流体动压润滑性能提供了新思路。采用单油酸甘油酯、油酸、季戊四醇四异硬脂酸酯、司盘80作为有机无灰减摩剂,以质量分数5%与PAO 5基础油进行调和,制备4种不同润滑油样,采用流体动压润滑试验机对比其摩擦学性能。试验结果表明,有机无灰减摩剂在边界润滑和混合润滑中均具有一定减摩效果,在流体动压润滑下减摩效果更明显。其中,含质量分数5%季戊四醇四异硬脂酸酯的油样具有最佳的减摩作用,其在流体动压润滑状态下可使基础油的摩擦因数降低19.6%。分子动力学模拟结果显示,有机无灰减摩剂在摩擦表面产生滑移现象,减少了分子间碳链的相互缠绕,进而降低流体动压润滑下的摩擦因数。     

Abnormal Vertical Dynamic Performance of Subway Vehicles

A serious wheel out-of-round phenomenon exists in a certain subway vehicle in China. More seriously, the vertical vibration of car body of this subway vehicle will go beyond the restriction of the standard criterion when the wheel out-of-round exceeds 0.2 mm in radial direction. And the wheel out-of-round problem could not be solved by polishing the rail or re-profiling wheels. Aimed at this problem, a further analysis is conducted on the structure and the suspension systems of the subway vehicle. It is thought that the additional stiffness function of the traction bar, caused by the short length and the bigger connection stiffness of the traction bar, leads to the problem that the subway vehicle is sensitive to the vertical impact. By taking into account the stiffness of the traction bar, dynamic simulation models of the subway vehicle are set up to study the influence of the additional stiffness function of the traction bar on the vertical dynamic performance of the subway vehicle through the simulation method. The response of the subway vehicle to vertical impact of a triangle pitch is also simulated. Simulation results indicate that the connection between the car body and the bogie will become rigid and the damping function of the secondary suspension will be decreased due to the additional stiffness of the traction bar in braking condition or running on curve track. Then the vertical response of the car body to vertical impact will be strengthened and the vertical ride index decreased. The vertical dynamic performance of the subway vehicle will be improved through the method of decreasing the connection stiffness of the traction bar, which has been validated by the simulation results. This method of improvement can effectively solve the problem of abnormal dynamic performance of this subway vehicle, and provide a foundation for a new theory about the traction bar system design.     

摩擦式安全离合器的动力性能研究

摩擦式安全离合器是一种结构简单,在运动中能迅速接合分离,可补偿两轴之间的偏移,能过载保护的安全离合器。其动力性能受诸多因素影响。为此,研究了影响动力传递的主要因素,通过试验提出安装误差将会影响运行的平稳性,制定了在有安装误差角度的两轴端连接处采用柔性连接的改进方案,并进行了实验验证。改进后摩擦式安全离合器运行平稳安全,解决了改进前存在动力传递性能明显下降的问题。     

不同摩擦系数对地铁列车曲线碰撞的影响

为分析不同摩擦系数对地铁列车曲线碰撞的影响,以某4节编组地铁列车为研究对象,建立其有限元模型。设计了动摩擦系数在0.05～0.5之间变化的6种碰撞工况,从碰撞能量转化、车辆点头姿态和车轮抬升量等方面,对地铁列车碰撞结果进行了详细的对比分析。研究结果表明,随着摩擦系数的提高,轮轨间滑移能逐渐增大,车体结构变形吸收的总内能变化不大,而防爬吸能装置和头车前端结构吸收的能量逐渐减少;碰撞能量转化、车辆点头姿态和车轮抬升量等增大或减小的趋势随摩擦系数的提高而逐渐变缓。     

跨座式单轨车辆动力学性能试验研究

针对某型跨座式单轨车辆,通过在车体和构架上布置加速度传感器,对车辆空载和满载时的加速度数据进行采集,基于GB/T 5599-2019对车辆的运行稳定性、运行品质、平稳性指标和舒适度进行评估.现场试验结果表明:该型车辆在90 km/h速度范围内,转向架未发生失稳现象,车体横向振动加速度和垂向振动加速度均小于2.5 m/s...     

工程车辆定变量节能液压系统动态性能研究

针对工程车辆能耗较高的问题,以装载机定变量节能系统为研究对象,基于Amesim和Adams建立了工作系统的机液耦合仿真模型;分析了定变量液压系统的动态特性,并得到了新系统的功率分配结果。通过定变量系统的能耗对比试验表明定变量液压系统大大降低了高压溢流和低压大流量能量损失;定变量系统比定量系统节油14.5%,具有较好的节能特性,为定变量系统的改进提供了参考。     

超高速切削在降低轨道车辆用空气弹簧摩擦因数中的应用

介绍了超高速切削加工技术。研究了将该技术应用在降低空气弹簧摩擦因数方面。     

斜楔摩擦角对三轴转向架动力学性能影响研究

为研究铁路货车顶置式斜楔轴箱悬挂结构中斜楔摩擦角对三轴转向架动力学性能的影响,基于车辆系统动力学和赫兹非线性接触理论,采用动力学性能仿真软件SIMPACK建立六轴平车非线性动力学模型,分析不同摩擦角对三轴转向架动力学的影响及变化规律.结果 表明,斜楔摩擦角的增大会使车辆垂向振动加速度增加,恶化垂向平稳性,影响车辆的轮重...