仿生非光滑摩擦衬片对制动器摩擦振动的影响

针对盘式制动器存在的制动摩擦振动现象和问题,设计出了 3种具有仿生非光滑表面的摩擦衬片,即圆坑摩擦衬片、方坑摩擦衬片和混合坑摩擦衬片.对3种摩擦衬片进行了制动摩擦振动模拟分析,并与具有光滑摩擦衬片的制动器摩擦振动特性进行了对比,进行了复特征值分析.结果表明:当对摩擦衬片表面进行仿生形貌处理后,制动器产生模态耦合的频率和...     

中重型汽车制动器用铆接式双层摩擦衬片的研制

为了降低制动器摩擦衬片成本，将常用中重型汽车铆接式制动器摩擦衬片改为双层结构衬片即表层为现生产配方原料，底层以废料填充。各项性能试验证明，该双层摩擦衬片可满足使用要求，其工艺易实现，并可合理利用摩擦材料，有利于清除废料。     

汽车制动器衬片"热膨胀"原因分析及控制研究

为了解决汽车制动器衬片的“热膨胀”问题，分析了产生“热膨胀”的主要原因，并对影响“热膨胀”的因素进行了试验及分析。提出了控制或减轻制动器衬片“热膨胀”的措施。通过试验表明，无石棉制动器衬片的摩擦磨损性能、热膨胀率均优于传统配方半金属基无石棉制动器衬片和传统工艺无石棉制动器衬片。     

湿式离合器动态接合特性的仿真与试验

根据湿式离合器接合过程特点,应用平均雷诺方程和粗糙表面弹性接触模型对湿式离合器接合过程建立了有效数学模型。利用Runge-Kutta方法对模型求解,分别研究了摩擦衬片渗透性、润滑油粘度、接合压力、动静摩擦因数特性等因素对接合过程中转矩响应、粘性转矩峰值、锁止处转矩峰值和接合时间的影响规律,并通过试验验证了模型的正确性和有效性。仿真与试验结果表明:增大摩擦衬片渗透性或接合压力,可以加快转矩响应,缩短接合时间;增大润滑油粘度,可以减慢转矩响应,缩短接合时间;减小摩擦副的动静摩擦因数差值,可以减小锁止处转矩峰值。     

汽车盘式制动器的研究进展

结合汽车盘式制动器设计与应用中存在的问题,对汽车盘式制动器摩擦衬片压力分布规律、摩擦偶件温度场和应力场的分布、摩擦衬片与对偶钢盘的摩擦机理、摩擦副间传热机理与制动噪声的研究状况进行了综述,探讨了今后的研究方向.     

制动蹄摩擦衬片最优铰削法的探索

根据制动鼓与制动蹄摩擦衬片的贴合与制动蹄的运动规律关系的分析，运用理论计算论证正确确定摩擦衬片曲率衬片曲率半径，保证蹄、鼓的正确贴合的规律，从而提出了蹄鼓式车轮制动器摩擦衬片最优铰削方法。     

新型盘式制动器衬片的研制及性能研究

设计研发安全环保和高性能的汽车制动器衬片是当前汽车行业研究重点。本文以钛基摩擦材料作为汽车制动器衬片的制备主料，分析确定了影响制动器衬片性能的材料配比；同时通过改进原料预处理工艺和压制成型工艺，进一步稳定了制动器衬片的摩擦性能。研究结果表明：改进后的制动器衬片在0～350℃范围内摩擦系数达到0.37～0.47，平均磨损率0.18(10-7cm³/Nm)，耐高温性能可达680～700℃。最后，通过综合分析法对试验数据进行分析，确定了汽车制动器衬片的最佳制备方案。     

缠绕式离合器摩擦衬片布线机理研究

分析了国内汽车用缠绕式离合器摩擦衬片的技术现状,确定了可满足离合器摩擦衬片工作性能和强度要求的布线方法,剖析了布线机理及规律。     

汽车用制动器衬片国家标准修订研究

GB 5763-2008《汽车用制动器衬片》于2009年9月10日开始实施。标准修订版非等效采用JISD4411-1993(2006确认),文中主要介绍衬片摩擦性能方面及试验方法的修订,结合我国产品现状和法规情况探讨未来的发展趋势。     

碳纤维复合材料汽车用无石棉制动衬片的研制

为了减少环境污染,综合利用资源,解决轿车零部件关键件的国产化问题,研制成功了碳纤维复合材料汽车用无石棉制动衬片。所研制的新一代碳纤维复合摩阻材料具有较高摩擦磨损性能,达到了国外同类产品的先进水平。     

High-frequency random vibration analysis of a high-speed vehicle–track system with the frequency-dependent dynamic properties of rail pads using a hybrid SEM–SM method

A hybrid Spectral Element Method (SEM)–Symplectic Method(SM) method for high-efficiency computation of the high-frequency random vibrations of a high-speed vehicle–track system with the frequency-dependent dynamic properties of rail pads is presented. First, the Williams-Landel-Ferry (WLF) formula and Fractional Derivative Zener (FDZ) model were, respectively, applied for prediction and representation of the frequency-dependent dynamic properties of Vossloh 300 rail pads frequently used in China's high-speed railway. Then, the proposed hybrid SEM–SM method was used to investigate the influence of the frequency-dependent dynamic performance of Vossloh 300 rail pads on the high-frequency random vibrations of high-speed vehicle–track systems at various train speeds or different levels of rail surface roughness. The experimental results indicate that the storage stiffness and loss factors of Vossloh 300 rail pad increase with the decrease in dynamic loads or the increase in preloads within 0.1–10,000?Hz at 20°C, and basically linearly increase with frequency in a logarithmic coordinate system. The results computed by the hybrid SEM–SM method demonstrate that the frequency-dependent viscous damping of Vossloh 300 rail pads, compared with its constant viscous damping and frequency-dependent stiffness, has a much more conspicuous influence on the medium-frequency (i.e. 20–63?Hz) random vibrations of car bodies and rail fasteners, and on the mid- (i.e. 20–63?Hz) and high-frequency (i.e. 630–1250?Hz) random vibrations of bogies, wheels and rails, especially with the increase in train speeds or the deterioration of rail surface roughness. The two sensitive frequency bands can also be validated by frequency response function (FRF) analysis of the proposed infinite rail–fastener model. The mid and high frequencies influenced by the frequency-dependent viscous damping of rail pads are exactly the dominant frequencies of ground vibration acceleration and wheel rolling noise caused by high-speed railways, respectively. Even though the existing time-domain (or frequency-domain) finite track models associated with the time-domain (or frequency-domain) fractional derivative viscoelastic (FDV) models of rail pads can also be used to reach the same conclusions, the hybrid SEM–SM method in which only one element is required to compute the high-order vibration modes of infinite rail is more appropriate for high-efficiency analysis of the high-frequency random vibrations of high-speed vehicle–track systems.     

活塞环表面PCVD复合陶瓷涂层的摩擦性能研究

采用等离子体化学气相沉积(PCVD)技术对活寒环表面进行复合陶瓷强化处理，并装机进行摩擦磨损试验，研究了复合陶瓷涂层的摩擦磨损特性。用扫描电子显微镜(SEM)、俄歇电子能谱(AES)、显微硬度计分析了活塞环表面涂层的磨痕形貌和元素分布。研究结果表明，活寒环表面PCVD复合陶瓷涂层具有显著的减摩抗磨能力，改善了发动机活塞的摩擦性能并提高了其使用寿命。     

长期循环荷载作用下管桩侧阻力试验研究

对软土地区静压管桩的静、动载试验结果进行分析,发现在工作荷载作用下软粘土中桩侧摩阻力呈抛物线分布,在循环动荷载下存在退化效应,并对此进行初步分析。分析结果表明:在动力循环荷载作用下,桩身上部软土层出现弱化现象,导致桩身上部的侧摩阻力减小,桩的下部粉质粘土与粉砂层侧摩阻力有所增加,但这种现象随动载循环次数的增加趋于稳定。     

Wet Single Clutch Engagement Behaviors in the Dual-Clutch Transmission System

A frictional torque was generated by a lubricated slip contact between a wet clutch pad and a steel separator during a wet clutch engagement. It is necessary to understand the generation of frictional torque to improve the performance of the frictional torque transfer and the durability of the wet clutch system. The analytical modeling of wet clutch torque transfer considers the effects of surface roughness, permeability, the elastic modulus of the frictional material, lubricant viscosity, temperature, etc. Experimental apparatus for wet clutch engagement was designed for the measurement of frictional torque transfer during wet clutch engagement. The experimental results were compared with the analytical results under various operational conditions for the verification of the theoretical analysis to evaluate the performance of the wet clutch system. Some correlations were investigated between the experimental and analytical results. We found that computation by analytical modeling can predict the effects of oil temperature, applied force, and slip speed, as well as engagement period and frictional torque transfer shapes.     

大吨位小半径环向预应力钢束张拉伸长量综合分析法

为研究大吨位小半径环向预应力钢束的孔道摩阻系数及钢束伸长值理论计算方法,以哈尔滨四方台斜拉桥为研究对象,进行索塔锚固区节段足尺模型试验及张拉工艺试验.通过试验现象观测、数据分析及孔道局部解剖,系统地分析了影响张拉伸长量的主要因素.研究结果表明:基于最小二乘原理的多变量数据拟合技术为分束计算μ值提供了可靠依据;引入等效束...     

Effect of temperature- and frequency-dependent dynamic properties of rail pads on high-speed vehicle–track coupled vibrations

The soft under baseplate pad of WJ-8 rail fastener frequently used in China’s high-speed railways was taken as the study subject, and a laboratory test was performed to measure its temperature and frequency-dependent dynamic performance at 0.3?Hz and at ?60°C to 20°C with intervals of 2.5°C. Its higher frequency-dependent results at different temperatures were then further predicted based on the time–temperature superposition (TTS) and Williams–Landel–Ferry (WLF) formula. The fractional derivative Kelvin–Voigt (FDKV) model was used to represent the temperature- and frequency-dependent dynamic properties of the tested rail pad. By means of the FDKV model for rail pads and vehicle–track coupled dynamic theory, high-speed vehicle–track coupled vibrations due to temperature- and frequency-dependent dynamic properties of rail pads was investigated. Finally, further combining with the measured frequency-dependent dynamic performance of vehicle’s rubber primary suspension, the high-speed vehicle–track coupled vibration responses were discussed. It is found that the storage stiffness and loss factor of the tested rail pad are sensitive to low temperatures or high frequencies. The proposed FDKV model for the frequency-dependent storage stiffness and loss factors of the tested rail pad can basically meet the fitting precision, especially at ordinary temperatures. The numerical simulation results indicate that the vertical vibration levels of high-speed vehicle–track coupled systems calculated with the FDKV model for rail pads in time domain are higher than those calculated with the ordinary Kelvin–Voigt (KV) model for rail pads. Additionally, the temperature- and frequency-dependent dynamic properties of the tested rail pads would alter the vertical vibration acceleration levels (VALs) of the car body and bogie in 1/3 octave frequencies above 31.5?Hz, especially enlarge the vertical VALs of the wheel set and rail in 1/3 octave frequencies of 31.5–100?Hz and above 315?Hz, which are the dominant frequencies of ground vibration acceleration and rolling noise (or bridge noise) caused by high-speed railways respectively. Since the fractional derivative value of the adopted rubber primary suspension, unlike the tested rail pad, is very close to 1, its frequency-dependent dynamic performance has little effect on high-speed vehicle–track coupled vibration responses.     

主缆与鞍座间摩擦抗力评估的混合解析数值法

为保障多塔悬索桥中主塔鞍座的抗滑移安全性，准确评估主缆与鞍座间的摩擦抗力，提出一种适用于鞍座摩擦抗力分析的混合解析数值法。首先，通过分析滑移临界状态下鞍座内索股的受力状态，将主缆与鞍座接触面间摩擦抗力的求解问题逐步分解，最终简化为求解鞍座任意截面处索股与鞍座接触面间压力分布的平面应变问题；其次，沿纵向将鞍座均匀离散化为多个截面，建立相应截面的二维有限元模型，并得出滑移临界状态下各截面处索股与鞍座接触面间的压力分布；采用将各段压力求和再乘以摩擦因数的方式求出主缆与鞍座间的摩擦抗力及其分布，建立适用于主缆与鞍座间摩擦抗力评估的混合解析数值法，并通过模型试验验证其准确性；最后，基于所提出的混合解析数值法对鹦鹉洲长江公路大桥实桥的中主鞍座摩擦抗力进行分析与讨论。研究表明：所提出的混合解析数值法计算结果和试验结果吻合良好，具有计算效率和精度高，评估流程简洁和工程应用便捷等优点，可作为评估主缆与鞍座间摩擦抗力的依据；主缆与鞍座接触面间压力的绝对值和摩擦抗力均呈由上到下、由松边到紧边递增的分布特性；通过设置竖向摩擦板以增加数个竖向摩擦板面，从而有效提高主缆与鞍座间的摩擦抗力，可大幅提高主缆与鞍座间的抗滑移安全性。     

直线滑动面法分析路基边坡稳定性的探讨

直线滑动面法适用粘聚力小的土质路基边坡稳定性分析,一般通过假设几个典型滑裂面,计算最小稳定系数,确定边坡的稳定性。直线滑动面法最危险滑动面直接解法可直接确定路基边坡最小稳定性系数,简化了路基边坡稳定性分析的计算工作。文中通过算例分析了粘聚力、边坡率和摩擦角对路基边坡稳定性的影响,表明边坡率和摩擦角对路基最危险滑裂面位置影响较显著,而粘聚力对路基最危险滑裂面位置几乎没有影响;粘聚力、边坡率和摩擦角对路基稳定性系数影响均显著。     

沥青碎石混合料永久变形评价方法的研究

在综述沥青混合料高温稳定性各种评价方法的基础上,对强度主要来源于内摩阻力的嵌挤骨架类沥青碎石混合料,本文采用具有侧限、能反映材料3向受力状态的动载压入法进行研究。该方法可直接测出不同荷载下的永久变形,反映出不同压实工艺、级配对材料永久变形的影响。试验结果说明该方法具有灵敏性和有效性,但受力图式受刚性侧限的限制,宜通过数据处理和选用或改善侧限方法改进之。     

重力式砌石挡土墙的因素敏感性计算分析

为了研究山区公路砌石高挡土墙变形破坏的产生机理并提出有效加固措施,结合浙江58省道重力式砌石挡土墙实例,采用不平衡推力法,对影响山区公路砌石高挡土墙的因素敏感性进行分析。研究结果表明,按因素敏感度从大到小排列,影响浆砌石重力式挡土墙整体稳定性的主要因素为潜在滑动面岩土体的内摩擦角、潜在滑动体饱水面积比、墙高、潜在滑动面岩土体的粘聚力和墙后填土的重度;影响浆砌石重力式挡土墙的最主要因素为潜在滑动面岩土体的内摩擦角和潜在滑动体饱水面积比;在对砌石高挡土墙进行加固处理时,必须优先考虑在墙身设置足够排水孔和选择渗透性好的填料的措施。