硅微陀螺梳齿驱动的面内失准分析

静电梳齿微驱动器因其结构简单、功耗低、灵敏度高、受温度影响小，成为硅微陀螺仪的主要驱动方式。静电梳齿微驱动器通常由活动梳齿和固定梳齿组成。理想情况下，活动梳齿平行地位于两固定梳齿中心位置。但由于加工误差、驱动结构不对称、扰动等因素，使得活动梳齿相对固定梳齿发生偏转。该文应用能量法及虚功原理，建立了梳齿之间的力与力矩平衡方程。得出了非理想情况下，偏离距离和转角的解析表达式，并分析得出了梳齿间的临界电压。经过数值仿真发现，梳齿面内既偏转又转动时的临界电压小于只发生偏转或转动时的临界电压。     

活塞与活塞环表面稀土自润滑摩擦学改性研究

采用稀土自润滑表面处理技术对桑塔纳 JV汽油发动机活塞与活塞环表面进行处理 ,并对原机进行活塞与汽缸、活塞环端口的超小间隙改造 (配缸间隙 - 5～ 2μm,活塞环开口 15 0μm ) ,通过台架试验对超小间隙发动机抗拉缸性能和摩擦功耗进行了考察 ;通过原子力显微镜对活塞表面的微观形貌和摩擦力进行了测试 .结果表明 :经稀土自润滑处理后活塞与活塞环表面产生大量孔穴和大量直径为 6 0～ 12 0 nm的球形聚集物 ,该特征表面明显增强了活塞与活塞环的抗拉缸性能 ,降低了自润滑表面的摩擦力 ,起到了良好的摩擦学改性作用     

几种弧形倒角变直径轴段的柔度或刚度的积分算法

一、引言 在研究往复内燃机的扭转振动时,常先把曲轴连杆活塞机构化成带薄盘的等径轴模型系统。机器直轴有时需分成直径大小不同的几段,因而其诸段的扭转弹簧系数也就依径变而有所区别。为了简化计算,在上述情形中,也需要先把这样的轴按照预先选定     

活塞环—环槽磨损试验机研究

在分析了内燃机活塞环和环槽的磨损类型之后，研制出一种活塞环－环槽磨损试验机。这种试验机具有强化试验功能，能够良好地模拟活塞环与环槽间的冲击载荷、相对滑动、温度和腐蚀性环境气氛，可以模拟出实际工况下的磨损失效类型，试验结果具有良好的可比性和重现性。     

曲轴轴向运动对粗糙表面曲轴主轴承润滑性能影响的研究

内燃机实际工作中，在多种影响因素综合影响下，曲轴进行旋转运动的同时，还存在沿轴承轴线方向的运动. 以某四缸四冲程内燃机曲轴-轴承系统为研究对象，综合考虑曲轴轴向运动、曲轴变形和摩擦表面粗糙度，基于平均Reynolds方程，建立了耦合曲轴轴向运动的粗糙表面主轴承润滑分析模型，着重研究了倾斜曲轴轴向运动对主轴承润滑特性的影响. 分析中，采用试验法实测曲轴沿轴承轴线方向的运动规律，应用有限单元法求解曲轴受载变形导致轴颈在轴承孔中倾斜状况. 结果表明:曲轴轴向运动对粗糙表面内燃机主轴承润滑特性影响显著；计及曲轴轴向运动时内燃机各主轴承轴颈轴心轨迹均为1条不封闭的三维空间曲线；曲轴轴向运动对主轴承润滑特性的影响程度与摩擦表面粗糙度直接相关；计及曲轴轴向运动时摩擦表面粗糙度对主轴承润滑特性影响趋势及程度均发生明显变化.      

活塞环组摩擦及润滑特性的综合分析

基于二维平均流量模型和微凸体接触模型，提出了一种分析内燃机活塞环组润滑的模型，同时还对油膜厚度进行了实测，理论值与实测值具有良好的一致性，并且运用这种模型求出了活塞环－缸套之间油膜厚度的三维分布，发现油膜厚度沿圆周方向存在不均匀性．在分析中还考虑了贫油的影响，而且首次探讨了活塞系统的二阶运动对活塞环组润滑特性的影响，给出了不同结构下活塞系统的摩擦力和摩擦功耗．     

用微机计算柴油机零部件的变形与应力

本文利用微机对我国几种机车柴油机的曲轴、连杆、活塞、气缸盖、气缸套和机体等主要零部件进行了计算,讨论了计算模型的建立以及边界条件和载荷的处理办法。     

弹性箔片动压径向气体轴承动特性的实验研究

建立了新型弹性箔片动压气体轴承性能测试实验台，在静载60N、转速9000r／min条件下进行轴承性能测试试验，通过中心插值法获得轴承中心的扰动速度和加速度，采用时域最小二乘法计算不同激振频率下的8个轴承动态线性刚度和阻尼系数，考察了激振频率对轴承动特性系数的影响．结果表明：轴颈中心扰动轨迹为椭圆形且振幅随动态激振频率增加而增大；刚度和阻尼系数的直接项随动态激振频率增加而减小；交叉刚度和阻尼相对激振频率的变化较小，且其值小于直接项；当激振频率与轴颈转动频率相同时，工频成分的影响较大，轴心扰动幅值明显增大，刚度和阻尼的直接项小于其它频率时的值．     

大型球轴承摩擦力矩试验台的研制及其实用性能的试验研究

为了研究大型轴承的摩擦性能，研制了一种可以测量外径２００～１５００ｍｍ球轴承的启动力矩、运转平均力矩、最大力矩和力矩变化幅值的大型轴承摩擦力矩试验台．这种试验台可以模拟轴承的启动角加速度、转动速度、预负荷和轴向工作负荷等．在此试验台上，对大型角接触球轴承成对预紧时的摩擦力矩与预紧量之间的关系进行了试验研究，并且根据试验结果，提出了一种适用于轴承外径２００～５００ｍｍ，转动速度低于３０ｒ／ｍｉｎ时计算摩擦力矩的经验公式．     

计及轴颈倾斜的径向滑动轴承湍流润滑分析

分析了轴颈倾斜状态下，径向滑动轴承的湍流润滑性能. 基于轴颈倾斜的统一Reynolds方程和能量方程，应用有限差分法求解了不同轴颈倾斜方位角、轴颈倾斜度、偏心率和平均雷诺数下的径向滑动轴承湍流润滑性能. 结果表明:轴颈倾斜方位角α=0°时，随着轴颈倾斜度的增大，轴承油膜的压力峰向轴承一端移动，轴承一端的轴向油膜温度梯度增大；α=90°时，随着轴颈倾斜度的增大，轴承油膜压力逐渐出现双峰分布，且向轴承两端移动，轴承两端的轴向温度梯度也不断增大. 在相同轴颈倾斜度增量下，轴承最大油膜压力、最高油膜温度、承载力和稳定工作力矩的增量随轴承中央截面偏心率的增大而增大. 相同轴颈倾斜度增量下，轴承最大油膜压力增量、最高油膜温度增量、承载力增量、摩擦系数减量和稳定工作力矩增量随平均雷诺数的增大而增大. 可见，径向滑动轴承湍流润滑分析中有必要考虑轴颈倾斜因素的影响.      

微乳化生物质燃油的往复运动摩擦学特性研究

采用发动机活塞环-缸套摩擦磨损试验台,研究了微乳化生物质燃油在活塞环-缸套摩擦副往复运动过程中的摩擦磨损特性.借助扫描电子显微镜及附带的能谱、X射线光电子能谱仪等分析测试手段考察了磨痕表面形貌及元素组成与含量、主要元素化学状态,探讨了摩擦磨损机理.结果表明,在微乳化生物质燃油润滑条件下,活塞环-缸套之间的摩擦系数和它们的磨损量均随着往复运动频率增加而增大,微乳化生物质燃油减摩性较0^#柴油好,耐磨性比0^#柴油差;摩擦磨损的机理归于微乳化生物质燃油中的极性基团如羧基（—COOH）易于吸附在摩擦副表面起到边界润滑作用,而乳化燃油中酸性物质在摩擦过程中加大了对摩擦表面的腐蚀,同时摩擦表面形成的Fe₂O₃氧化膜在摩擦力作用下脱落并充当磨粒,从而使磨损加剧.     

氟橡胶O型圈低压气体密封黏滞摩擦特性实验

开展了低气体密封压力条件下的氟橡胶O型圈低压黏滞摩擦特性实验研究.对氟橡胶O型圈与不锈钢2Cr13摩擦副的摩擦力的时变曲线进行测量,重点分析了密封压力、O型圈压缩率和滑动速度对O型圈黏滞摩擦力的影响规律.结果表明:随压缩率的增加,氟橡胶O型圈摩擦力增加,并呈现出明显的回弹特征,即滞后摩擦力增加且释放时间增加;随着密封压力的增加,其所受最大静摩擦力、滑动摩擦力与滞后摩擦力均呈现非线性变化,且存在一极大值;减小往复运动速度,摩擦力数值增大,但摩擦力极值对应的密封压力值变小.     

Tribological behavior of the boron succinimide on cylinder liner and piston ring surfaces

In this study, tribological performances of two types of anti-wear additive, boron succinimide anti-wear package and ZnDTPs, were investigated in the cylinder liner and piston ring tribological system with a reciprocating tribotest machine. The tribological performances of oils were evaluated in three main contexts including wear rates, surface tribofilm formation and friction. Results showed that NP-3 (boron succinimide containing) lubrication oil which was environment and catalyst friendly, can be an alternative lubrication oil with its tribological performance due to its friction and wear reduction capacity.     

活塞二阶运动及活塞裙部摩擦的瞬态分析

为分析不同工况下内燃机活塞-缸套系统的摩擦学和动力学行为,本文从内燃机系统动力学分析入手,结合流体润滑方程,建立了考虑系统变惯量影响的活塞二阶运动与摩擦学行为的瞬态分析模型.以某型号单缸机为例,计算和比较了整个启动过程中曲轴转速、二阶运动及摩擦功耗的变化;对比分析了启动时第一周期与稳定运行时某一周期内活塞二阶运动和活塞裙部摩擦学行为的差别.结果表明:该模型可应用于内燃机动力学和摩擦学行为的稳态及瞬态分析.     

柴油发动机碳烟对缸套/活塞环摩擦学性能影响的研究

通过SRV IV摩擦磨损试验机考察了柴油机碳烟对柴油机缸套/活塞环摩擦副摩擦磨损性能的影响,借助扫描电子显微镜及能谱仪、三维表面形貌仪和拉曼光谱仪探讨了碳烟颗粒的摩擦学作用机理.结果表明:碳烟颗粒在高载荷时可以降低缸套/活塞环摩擦副间的摩擦系数,但在低载荷时对摩擦系数影响不大;碳烟颗粒会加剧缸套的磨损,其磨损形式主要为磨粒磨损.碳烟颗粒表现出减摩性的主要原因是其外层的乱层石墨在摩擦热和剪切作用下发生了剥离并在摩擦副表面形成了润滑膜.     

Static and dynamic responses of a microcantilever with a T-shaped tip mass to an electrostatic actuation

In this study, nonlinear static and dynamic responses of a microcantilever with a T-shaped tip mass excited by electrostatic actuations are investigated. The electrostatic force is generated by applying an electric voltage between the horizontal part of T-shaped tip mass and an opposite electrode plate. The cantilever microbeam is modeled as an Euler–Bernoulli beam. The T-shaped tip mass is assumed to be a rigid body and the nonlinear effect of electrostatic force is considered. An equation of motion and its associated boundary conditions are derived by the aid of combining the Hamilton principle and Newton's method.An exact solution is obtained for static deflection and mode shape of vibration around the static position. The differential equation of nonlinear vibration around the static position is discretized using the Galerkin method. The system mode shapes are used as its related comparison functions. The discretized equations are solved by the perturbation theory in the neighborhood of primary and subharmonic resonances.In addition, effects of mass inertia, mass moment of inertia as well as rotation of the T-shaped mass, which were ignored in previous works, are considered in the analysis. It is shown that by increasing the length of the horizontal part of the T-shaped mass, the amount of static deflection increases,natural frequency decreases and nonlinear shift of the resonance frequency increases. It is concluded that attaching an electrode plate with a T-shaped configuration to the end of the cantilever microbeam results in a configuration with larger pull-in voltage and smaller nonlinear shift of the reso-nance frequency compared to the configuration in which the electrode plate is directly attached to it.     

Experiment and theory on a twisted ring under quasi-static loading

Consider an initially straight rod of circular cross section bent into a circular ring so that the cross sections of the two ends meet face to face. In this paper we study, theoretically and experimentally, the behavior of the ring as the relative rotation between the two end cross sections increases quasi-statically. The variables of interest are the relative rotation angle and the corresponding twisting moment. In theoretical aspect the ring is modeled as an elastica and its deformation is calculated by shooting method. It is found that a ring with dimensionless rod radius 0.001 jumps to a two-point self-contact deformation when the relative rotation angle reaches a critical value. As the rotation angle continues to increase, the deformation evolves smoothly to three-point contact and finally to point-line-point contact. In the experiment we build a simple device to control the relative rotation angle between the two end cross sections. Measurements of twisting moment and relative rotation angle are recorded and compared with theoretical prediction. Reasonable agreement between experiment and theory is observed. Especially the jump phenomenon is confirmed. Installation misalignment and plastic deformation of the rod are the main causes of discrepancy between theory and experiment.     

THE ERROR ANALYSIS IN MEASUREMENT OF RIGID BODY INERTIA BY THE FALLING BODY METHOD1)

为了分析刚体转动惯量实验测定中摩擦力矩变化对测量结果的影响,本文对采用落体法测角加速度方法进行了实测检验。结果表明,摩擦力矩随载物系统转速增大而显著增加,系统空载测量时,减速过程角加速度对应平均转速远大于加速过程平均转速,如果不进行修正,则导致计算结果偏低。而相同质量砝码拉动系统负载测量时,加速过程和减速过程对应平均转速相对接近,测量值主要受测量随机误差影响。上述结果有利于进一步开展转轴摩擦力矩随转速变化系统性的研究。     

Analysis of Fan Waves in a Laboratory Model Simulating the Propagation of Shear Ruptures in Rocks

The fan-shaped mechanism of rotational motion transmission in a system of elastically bonded slabs on flat surface, simulating the propagation of shear ruptures in super brittle rocks, is analyzed. Such ruptures appear in the Earth’s crust at seismogenic depths. They propagate due to the nucleation of oblique tensile microcracks, leading to the formation of a fan domino-structure in the rupture head. A laboratory physical model was created which demonstrates the process of fan-structure wave propagation. Equations of the dynamics of rotational motion of slabs as a mechanical system with a finite number of degrees of freedom are obtained. Based on the Merson method of solving the Cauchy problem for systems of ordinary differential equations, the computational algorithm taking into account contact interaction of slabs is developed. Within the framework of a simplified mathematical model of dynamic behavior of a fan-shaped system in the approximation of a continuous medium, the approximate estimates of the length of a fan depending on the velocity of its motion are obtained. It is shown that in the absence of friction a fan can move with any velocity that does not exceed the critical value, which depends on the size, the moment of inertia of slabs, the initial angle and the elasticity coefficient of bonds. In the presence of friction a fan stops. On the basis of discrete and continuous models, the main qualitative features of the behavior of a fan-structure moving under the action of applied tangential forces, whose values in a laboratory physical model are regulated by a change in the inclination angle of the rupture plane, are analyzed. Comparison of computations and laboratory measurements and observations shows good correspondence between the results.     

两种螺旋角干气密封环端面摩擦特性试验研究

干气密封环端面的接触摩擦不容忽视,在槽型设计与优化时也应该考虑端面的摩擦特性.利用端面摩擦磨损试验机,分别对16°和18°两种螺旋角的螺旋槽干气密封环进行测试,通过对比分析磨损量、摩擦温度、摩擦系数以及表面粗糙度来讨论密封环的摩擦特性和两种螺旋角对端面摩擦性能的影响.结果表明:18°螺旋角试验的磨损量、摩擦温升和摩擦系数均稍大于16°螺旋角试验,说明18°螺旋角试件的磨损比16°螺旋角的更加剧烈;石墨环被螺旋槽覆盖的外圈粗糙度的变化有较大的差异,内圈粗糙度变化相似,说明槽型参数的改变对石墨环磨损的影响主要体现在外圈.试验结果为今后端面摩擦学性能的研究及槽型优化提供了依据.