镀银膜轴承在油和脂润滑下的摩擦性能

试验研究镀银膜轴承在干摩擦、润滑油和润滑脂复合润滑下的摩擦性能。试验结果显示:在中低转速下,镀银膜轴承在银膜和液体润滑剂(油和脂)复合润滑下的摩擦因数仅相当于银膜干摩擦下摩擦因数的10%左右,且变化平稳;在高转速下,试验轴承在银膜和液体润滑剂复合润滑下的摩擦因数随转速增加而增加,且银膜与润滑脂复合润滑条件下的摩擦因数随转速增加得更快,但仍小于银膜干摩擦下的摩擦因数;镀银膜轴承在银膜和液体润滑剂(油和脂)的复合润滑下的磨损小于银膜干摩擦时的磨损;中低转速下,镀银膜轴承在液体润滑剂(油和脂)复合润滑下的摩擦磨损性能远优于银膜干摩擦时的摩擦磨损性能。     

纳米二氧化硅对锂基润滑脂摩擦学性能的影响

利用溶胶-凝胶法,以正硅酸乙酯为原料制备了纳米二氧化硅微粒,通过透射电子显微镜对其结构进行了表征,利用四球摩擦磨损试验机测定了添加不同含量纳米二氧化硅锂基润滑脂摩擦学性能,采用扫描电子显微镜观察磨损表面形貌。结果表明:制备的纳米二氧化硅是粒径为60 nm左右的球形微粒,具有很高的表面能和表面活性;纳米二氧化硅作为锂基润滑脂添加剂能够提高最大无卡咬负荷和烧结负荷,降低摩擦因数,添加量为2.0%(质量分数)时的润滑剂性能最好,相对应的钢球磨斑直径最小,摩擦因数最低。     

基于Carreau流变模型的渐开线齿轮摩擦因数研究

结合载荷分担概念和弹流润滑理论,研究润滑剂的流变性对渐开线齿轮油膜厚度、摩擦因数等润滑特性的影响;分别采用Carreau流变模型和Doolittle-Tait自由体积黏度模型描述润滑剂的剪切稀化特性及黏压关系,研究齿轮载荷、转速、表面粗糙度和润滑剂压黏系数对摩擦因数的影响。研究结果表明:不同的润滑剂剪切稀化特性不同,因此油膜厚度、油膜承载比例和摩擦因数均不同;摩擦因数随着转矩的增大先显著增大,当超过某一转矩值时,摩擦因数开始缓慢变化;摩擦因数随着转速的增加先显著减小,当转速增加至某一值时摩擦因数又随之增大;随着表面粗糙度和润滑剂压黏系数的增大,摩擦因数均明显增大。     

高载荷条件下环氧树脂涂层摩擦学性能研究

以45#钢为基体制备了环氧树脂(EP)涂层,并用自制的摩擦因数测试装置研究了该涂层在不同润滑条件下的摩擦学性能.结果表明:加载力在500～2 500 N时,EP涂层具有优良的减摩性能,并随着载荷增加,摩擦因数呈下降趋势;添加润滑剂后,可进一步降低涂层摩擦因数,其中固体润滑脂润滑效果最好,最低动摩擦因数达到0.048.     

辛硫醇改性氧化石墨烯在润滑脂中的摩擦学性能

氧化石墨烯(GO)的结构中拥有众多含氧基团,可作为化学反应的活性位点。以辛硫醇为改性剂对GO进行修饰,得到辛硫醇-GO。使用红外光谱(FTIR)、X射线衍射(XRD)、X射线光电子能谱(XPS)、热重分析(TGA)对其进行结构表征。将GO、辛硫醇-GO作为添加剂与润滑脂复配,考察其在润滑脂中的摩擦学性能。依据ASTM D2596-15标准方法,采用四球机测定GO润滑脂的抗磨减摩性能,使用白光干涉三维表面轮廓仪测定钢球表面形貌和磨损率。结果表明:GO可略微减小润滑脂的摩擦因数和磨损率;辛硫醇-GO对润滑脂的润滑性能有较大提升,可使润滑脂的摩擦因数减小11.7%,磨损率减少31.5%。XPS磨损表面分析表明,摩擦过程中会有GO颗粒吸附到金属表面,而且改性GO润滑脂中的活性硫元素会与钢球表面反应,生成硫化铁,减少钢球表面的摩擦磨损,从而有效提升润滑脂的润滑性能。     

润滑脂对膨胀管材料摩擦性能的影响

膨胀管膨胀过程中的摩擦影响到膨胀的难易程度和胀后套管的性能,选择一种合适的润滑介质降低膨胀过程中的摩擦因数对膨胀管技术来说非常重要。使用摩擦模拟实验的方法,研究在二硫化钼锂基脂、铅基润滑脂和没有润滑脂的3种条件下普通N80膨胀管材料的摩擦性能,使用扫描电子显微镜对不同载荷下试样的磨损表面进行分析,并讨论不同润滑条件下的磨损机制。结果表明,润滑脂的加入可以显著降低膨胀过程中膨胀管材料的摩擦因数和磨损量,磨损机制也从原来的磨粒磨损变成黏着磨损,铅基润滑脂由于摩擦因数更低具有最好的润滑效果,可以显著提高膨胀管材料在膨胀过程中的耐磨性能。     

表面织构在脂润滑条件下的摩擦性能研究

采用声光调Q二极管泵浦Nd:YAG激光加工系统在H13钢表面加工出不同密度的织构,以润滑脂作为润滑剂,利用MMW-1A型微机控制万能摩擦磨损试验机考察表面织构在不同载荷、不同转速条件下的摩擦磨损特性。实验结果表明:在脂润滑条件下表面织构能有效改善摩擦副表面的摩擦性能;与光滑无织构试样相比,表面织构试样的摩擦因数显著降低;一定范围内,随着织构密度的增加,平均摩擦因数呈现出先减小后增大的趋势,且织构密度为10%时的平均摩擦因数最小,最小平均摩擦因数为0.18,较光滑无织构试样减小32.23%;摩擦因数随着试验载荷的增大而减小,但随着转速的增加呈现出先减小后增大的变化趋势。     

钻井液污染润滑脂对牙轮钻头轴承摩擦学性能的影响

高温或冲击载荷会引起钻井液泄漏进入复合锂基润滑脂,从而影响牙轮钻头滑动轴承润滑及摩擦磨损性能。采用MCR102旋转流变仪对含有不同质量分数钻井液的复合锂基润滑脂进行流变性测试,并采用MDW-1型摩擦磨损试验机开展牙轮钻头滑动轴承模拟工况下轴承单元摩擦学实验,研究钻井液质量分数对轴承摩擦磨损性能的影响。结果表明:钻井液的污染将降低润滑脂的黏度,改变润滑脂的流变性能;钻井液的污染总体上增大了滑动轴承单元摩擦因数及摩擦因数波动幅度,同时加大轴承的磨损,且在高转速下,润滑脂中较低含量的钻井液就会使滑动轴承单元的摩擦磨损达到最大值;钻井液中的超细碳酸钙和重晶石颗粒引起的磨粒磨损和犁沟效应,可能导致滑动轴承快速失效。     

复合铝-锂基润滑脂的制备及性能研究

为提高复合铝基润滑脂的综合性能,采用矿物油(KN4010)为基础油,以12-羟基硬脂酸、硬脂酸、苯甲酸、氢氧化锂、异丙醇铝为稠化剂原料,制备一系列复合铝-锂基润滑脂。通过对其滴点、锥入度、钢网分油与摩擦因数等重要参数的表征,研究基础油含量与铝锂比例对复合铝-锂基润滑脂性能的影响。结果表明:铝锂比例为3∶1时制备的复合铝-锂基润滑脂具有较高的滴点、极低的钢网分油量与较低的蒸发损失,同时摩擦因数与磨斑直径均明显低于复合铝基润滑脂。复合铝-锂基润滑脂中Al、Li元素可能在减磨过程中起到共同作用,从而使摩擦因数与磨斑直径均明显低于复合铝基润滑脂。     

铁路轮轨润滑脂的研制

采用IR、XRD、SEM-EDS等手段,对常用铁路轮轨润滑脂进行剖析,得到润滑脂的基础油种类和添加剂组成。研制一种新型铁路轮轨润滑脂,并与常用铁路轮轨润滑脂的性能进行比较。结果表明:研制的润滑脂的最大无卡咬负荷为863 N,比常用铁路轮轨润滑脂的大一倍多,其摩擦因数为0.008～0.032,明显小于常用铁路轮轨润滑脂的0.039～0.051,但烧结负荷小于常用铁路轮轨润滑脂;研制的润滑脂具有更好的胶体稳定性和耐热性。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.