人体手背皮肤的摩擦学特性试验研究

为了研究手部皮肤的生物、摩擦学特性和为护手产品的相关研究提供科学依据，采用微观摩擦试验机测定手背皮肤的摩擦因数，经过对24位健康志愿者的左右手手背皮肤表面的摩擦学特性试验，结果是：在受试者手背皮肤保持自然洁净的情况下，女性左、右手手背皮肤的摩擦因数平均值分别为0．49和0．48，而男性左、右手手背皮肤的摩擦因数平均值分别为0.38和0.39；在受试者手背涂抹护肤用甘油后，其皮肤的摩擦因数明显升高且均超过1，保持时间大约220min。研究结果表明：男性手背的摩擦因数比女性偏低；男、女手背不同位置处皮肤的摩擦因数相差不大；人体左、右手手背的摩擦因数无明显差别；甘油的润肤保湿效果显著。     

关于皮肤摩擦学特性的研究

综述了皮肤摩擦特性的研究进展、实验方法和设备及不同因素对皮肤摩擦特性的影响 ,分析了皮肤摩擦特性在相关领域中的作用 ,并对皮肤摩擦学的研究发展方向提出了建议。     

皮肤-纺织品的摩擦特性试验研究

为了定量研究纺织品与人体皮肤之间的摩擦特性,采用微观摩擦试验机对4种织物与20位男女手臂前臂皮肤之间的摩擦因数进行测试。结果表明:皮肤-织物的平均摩擦因数在0.30~0.50之间,其中男性皮肤-织物的平均摩擦因数在0.30~0.36之间,女性皮肤-织物的平均摩擦因数在0.40~0.50之间。织物表面特征,如表面形状、纹理特点、组织结构、平整度、致密度和弹性等,以及纤维本身的表面特征,是织物表面摩擦特性存在差异的根本原因。4种织物的平均摩擦因数由高到低分别为全毛绒面呢、羊皮、真丝绸和本色平纹棉布,其中丝绸和平纹棉布的平均摩擦因数比较接近;在与不同纺织品摩擦时,女性皮肤-织物的平均摩擦因数普遍比男性高。     

针织物与皮肤摩擦性能的测试方法

为了研究针织物与皮肤的摩擦性能测试条件,用织物与皮肤摩擦特性测试仪对5种不同规格的针织物和皮肤进行摩擦实验,对比平均动摩擦力、动摩擦力的平均差不匀率和变异系数3个指标的差异,根据摩擦曲线的稳定性和实际测试条件,推荐出常规针织物和皮肤的实验条件。实验发现,张力与动摩擦力呈正相关关系,与动摩擦力的平均差不匀率呈负相关关系,60cN的张力条件下平均动摩擦力的变异系数最小。摩擦速度与动摩擦力的关系不大,500mm/min的摩擦速度下,动摩擦力的变异系数及其差不匀率均最小。另外,以此测试条件在95%的置信概率水平下,每对针织物和皮肤配副进行4次摩擦实验即可满足测试需求。     

摩擦引起的模态耦合不稳定性分析

模态耦合是摩擦系统振动不稳定性的重要机理之一,它会受到系统摩擦副的结构阻抗特性和摩擦接触特性的显著影响。针对一类由一个摩擦副部件的不同方向模态导致耦合不稳定性的现象,建立2自由度摩擦振动动力学模型,推导在摩擦副部件机械阻抗特性相差极大的条件下,系统摩擦耦合模态不稳定性及其对摩擦力方向的依赖性,以及研究了不稳定区域对摩擦副结构和摩擦接触特性参数的敏感性;同时,也分析摩擦副部件的自身约束模态频率和系统接触模态频率对系统摩擦耦合模态区域和频率的影响。这为指导以避免模态耦合的摩擦振动系统的结构参数和摩擦接触参数匹配,以及识别摩擦振动不稳定的摩擦副模态来源提供了理论依据。     

摩擦系统特性对制动器衬片压力分布规律的影响

根据金属型、非金属型湿摩擦以及干摩擦系统特性的不同，分析摩擦过程中系统弹性，热膨胀和磨损对制动器衬片压力分布的影响，统一了现有两处模型的适用条件与范围，提出了“金属型湿式衬芘压沿半径线性增长”的新模型。     

多绳摩擦式提升机提升系统动态特性分析

针对矿用多绳摩擦式提升机在多绳缠绕时卷筒受力复杂、空载以及满载工况下动态特性复杂等问题，利用计算机数值模拟分析方法对矿用多绳摩擦式提升机提升系统受力变化进行研究，利用Simulation X对矿用多绳摩擦式提升机空载与满载工况下的动态特性进行研究，得出空载启动转速平稳、无超调，在满载启动时系统响应速度比较慢，需要经过6.5s后才能够恢复到稳定状态。结果表明：整个控制系统运行平稳、超调量小、速度波动小，能保证提升系统的平稳运行，分析结果可为后期多绳摩擦式提升系统的控制优化提供参考。     

具有动压反馈的配流轴的动态特性

在径向柱塞泵配流轴摩擦副的静压支承系统中，增加了压力补偿元件，使该系统具有动态反馈本文讲座了配流轴摩擦和静压支承在两类工况下动态特性。     

[轮轨磨耗及预测]高速列车制动摩擦块切入端特征对制动界面特性的影响

在自行研制的高速列车制动缩比试验台上，对四种不同安装方向下的三角形摩擦块进行拖曳制动试验，研究了摩擦块的切入端特征对制动界面特性的影响,并采用有限元方法分析不同摩擦切入端特征下摩擦块的接触压力分布特点，探讨了摩擦块表面接触压力分布与其表面热分布、振动噪声特性的内在关联。结果表明：在摩擦制动过程中，摩擦块的切入端存在应力集中现象，尤其是当摩擦切入端是一个角的两条边时，摩擦切入端的角附近区域应力集中更为明显，从而引起制动系统产生高强度的振动噪声并导致摩擦块表面局部高温现象。     

液体动压轴承特性试验方法的研究

简要说明了液体动压轴承的特性与润滑油的粘度，滑动速度、轴承比压及轴承摩擦系统有关，从而制定了特性试验方法，采用ＣＡＴ试验系统，并给出了几种关系特性曲线。     

The Effect of Changing Fingerprinting Directions on Finger Friction

The contact characteristic between finger and objects changes due to the different deformation of a fingerprint when the finger slides in different directions. To understand this mechanism better, a new type of experimental setup was designed, and specific tests were conducted. We analyzed the regularity of the friction coefficient in two sliding directions. When the finger was sliding on surfaces with different roughness values, normal forces, and contact angles, the fingerprint deformation was captured by the Asana microscope. The following were inferred from the conducted experiments. Firstly, the friction coefficient decreases with increasing sample roughness and normal force. Secondly, the friction coefficient first decreases and then increases with increasing contact angle. Thirdly, the distance between the fingerprints increases when the finger is dragged, leading to an increase in contact area, thereby improving the friction coefficient. Finally, the result will be opposite to the previous inference when the finger is squeezed hard for fingerprinting.     

Measurement of friction force and effects of oil fortifier in engine journal bearings under dynamic loading conditions

Commercial base oil and oil fortifier added to this oil are used to investigate the frictional behavior of the engine journal bearings using the theoretical Reynolds equation and experimental test rig. In the theoretical part of the study, the Reynolds equation that states the pressure distribution and friction force with finite width was solved by using the finite difference method. In the experimental part of the study, a new design test rig was conducted to measure the friction force, the lubricant film thickness of the engine journal bearing using base oil under dynamical loaded conditions. The effect of oil fortifier was detected measuring the friction force every three minutes in each 360 crank angle during 15 minutes of experiment. As the theoretical friction results showed similar variation with the experimental measurements of engine bearings, adding oil fortifier to the base oil presented a substantial reduction of friction force during the testing period.     

载荷和相对湿度对微摩擦力的影响

利用自制的微摩擦和粘附力测试装置，研究了在微牛量级载荷下，载荷和相对湿度对Si（100）材料与Si3N4材料组成的摩擦副的最大静摩擦和滑动摩擦的影响。实验发现，最大静摩擦力和滑动摩擦力均随着载荷的增大而增大，而最大静摩擦因数和滑动摩擦因数则随载荷增大而降低。相对湿度对摩擦的影响则随不同载荷的范围而有所不同。载荷较小时，相对湿度对摩擦因数的影响较大；载荷较大时，则相反。利用单峰接触的模型，建立了相对湿度与摩擦力关系的公式。     

汽车减振器油封摩擦力变化规律研究*

采用数值模拟与实验验证相结合的方法开展对汽车减振器油封摩擦特性的研究,得到不同工况下的摩擦力变化规律;在往复油封摩擦力实验台上研究了摩擦力随润滑油温度、润滑油压力和活塞杆速度的变化规律。结果表明:随活塞杆速度的增加油封摩擦力呈先增加再减小后趋于稳定的变化规律;随润滑油温度的升高油封摩擦力逐渐减小;随润滑油压力的增加油封摩擦力逐渐增大。根据油封摩擦力变化规律,可以推断出活塞杆速度较低、润滑油温度较高、润滑油压力较低时,应使得减振器油封有较大的过盈量或抱紧力,以提高汽车减振器的性能和使用寿命。实验结果与数值仿真结果基本一致,验证了混合润滑数值模型的正确性。     

The effect of longitudinal tangential vibrations on friction and driving forces in sliding motion

The main purpose of the work has been to qualitatively and quantitatively analyse the influence of longitudinal tangential vibrations on friction and driving forces in a sliding motion. Computational models were developed and implemented in a combined Matlab-Simulink environment. Both the dynamic Dahl's and the Dupont's and classical Coulomb's friction models were used. The influence of vibration velocity amplitude on the friction force in the presence of tangential longitudinal vibrations and on reduction of the driving force in sliding motion was analysed. It revealed that the commonly accepted view that the reduction of the average friction force is a consequence of cyclic changes in the sign of the friction force vector, only when the amplitude of vibration velocity is greater than the sliding motion velocity, is erroneous. The phenomenon was also observed without any changes in the sign of friction force vector. The results of simulations were compared with experimental data obtained with the use of a test rig specifically designed for the work. The Dahl's friction model led to the best correlation.     

端面摩擦磨损自动检测系统的设计

端面摩擦磨损试验可以模拟和检测面接触摩擦副的摩擦学特性。设计了端面摩擦磨损试验自动检测系统。首先在建立摩擦力和摩擦因数测量的数学模型的基础上,设计了摩擦力参数的自动检测系统,然后设计了端面试验机的智能化测控系统。使用结果表明,使用该自动检测系统的端面摩擦磨损试验机可实时检测和处理载荷、速度、温度、摩擦力和摩擦因数等参数信息,并以表格或图像曲线形式显示,有利于对试验材料的摩擦学特性变化作出实时、客观、量化的评估。     

Role of Rubber Stiffness and Surface Roughness in the Tribological Performance on Ice

The aim of this work is to investigate the effect of slider surface roughness and stiffness on the friction between rubber compounds and ice surfaces in order to provide insight into rubber–ice friction generation mechanisms. For this purpose, rubber compounds were designed to have different levels of macroscopic roughness and cured stiffness by modifying the filler system and plasticizer loading. In order to accurately evaluate the effects of surface and bulk rubber property on ice friction, linear friction tests were performed on laboratory ice with varied frictional heat buildup by modifying the friction test protocol. The results showed that the friction force was in general increased through the ploughing effect of a rough rubber block sliding on smooth ice. The increase in friction by ploughing was more pronounced when the contacting rubber block had sufficiently low stiffness and when the accumulation of frictional heat on ice was sufficiently high. It was also evidenced that a sufficiently hard rubber with test conditions leading to low heat buildup on ice could nevertheless lead to an opposite influence of roughness on rubber–ice friction; that is, lower friction force with a slider with a higher roughness.     

Friction property study of the surface of ZDDP and MoDTC antiwear additive films using AFM/LFM and force curve methods

The friction properties and material differences of the surface of ZDDP and MoDTC antiwear additive films, which give clear evidence of different friction coefficients in a pin-on-disc test, have been studied using atomic force microscopy (AFM)/lateral force microscopy (LFM) and force curve methods. The AFM/LFM observations show that the friction force on the surface of MoDTC additive films over the sliding area of a steel disc is lower and the friction force of ZDDP additive films is higher than that of afilmless area. Lateral force scope-trace evaluations reveal that the ratio of the friction forces on the surface of the ZDDP film, the filmless area, and the MoDTC film under the same normal force is approximately 1.5:1.0:0.7. Force curve measurements indicate that the surface materials of the ZDDP film, thefilmless area, and the MoDTC film differ according to their attractive forces, that is 29 nN for the ZDDP film, 22 nN for the filmless area, and 12 nN for the MoDTC film. These results correspond to the friction behaviour in the pin-on-disc test and also agree with the idea of the formation of solid MoS₂ lubricant from MoDTC additives on the surface of the antiwear film.     

Study of the influence of the friction clutch operability on the performance of the switch motor

In this paper, the results of studying the efficiency of an SP-6 M switch motor have been presented. The friction clutch plays an important role during the transmission of torque from a motor to an actuator. To study a motor switch, a test rig was developed in order to determine the necessary force to move switchblades depending on the pressing force of the friction clutch. The tribological properties of the friction disk materials have been investigated using a specially designed test machine.     

基于LuGre模型的转子压缩机滑片-滑槽运动副摩擦力测试

为研究转子压缩机滑片-滑槽运动副的摩擦特性,根据LuGre摩擦模型的建模方法和该运动副的运行特点及工况特点,设计并搭建了滑片-滑槽等效摩擦力测试系统,分析了该系统的摩擦力跃动现象、数据采集区域和摩擦力测量的重复性问题,并进行了摩擦力测试实验。结果表明：该摩擦力测试系统可以根据压缩机的实际工况,对滑片均匀加载相应的正压力FH,并能实现不同匀速直线运动下的摩擦力测量;可以有效消除低速润滑不均匀导致的摩擦力跃动现象;通过润滑初始化可以较准确地获得基于滑片速度变化的摩擦力表达曲线。实验结果与数值计算结果吻合,从而为正确辨识LuGre摩擦模型的参数提供了实验依据。