高载荷条件下石墨-石墨摩擦副的摩擦学特性研究

利用研制的高载荷条件下摩擦因数测试装置,研究了石墨/石墨摩擦副在空气、水和油介质中的摩擦学特性。结果表明在4~15MPa范围内,随着载荷的增加,摩擦副在空气、水和油介质中的摩擦因数都逐渐降低;在油介质中摩擦副的摩擦因数最小,在水介质中摩擦因数变化最平稳,在空气中摩擦因数最大,且随载荷的增加变化幅度最大。磨损表面原始形貌对比分析表明,在空气中,摩擦副表面处于边界润滑状态,主要磨损机制是粘着磨损和犁削;水润滑条件下为轻微犁削;油润滑条件下,摩擦副表面处于为边界润滑和流体润滑状态,油中的减摩剂对试样表面有抛光作用。     

铜镍锡合金干滑动磨损行为研究*

大型装备上的铜镍锡合金工件常常工作在润滑不足或者无润滑的工况条件下,因此有必要研究铜镍锡材料在干摩擦下的性能。采用CEF-I型销-盘式磨损试验机对铜镍锡合金在不同载荷与转速条件下进行干滑动摩擦磨损试验,采用扫面电子显微镜、能谱仪和轮廓检测仪对磨损表面进行检测,研究铜镍锡合金的干滑动磨损行为,并探讨其磨损机制。结果表明：在转速一定时,平均摩擦因数随载荷增大总体呈波动下降趋势,铜镍锡合金试件磨损量先缓慢增加,在较高载荷下快速增加;在载荷一定时,平均摩擦因数随转速增大先增大后减小,铜镍锡合金试件磨损量总体呈先减小后增大趋势;随着载荷的增大,铜镍锡合金的磨损机制由轻微黏着和剥层磨损到明显的黏着和剥层磨损,再到严重的黏着和疲劳磨损,随着转速的增大,铜镍锡合金的磨损机制由磨粒磨损转变为黏着磨损再到剥层磨损。在较低载荷下,随着转速的增大,铜镍锡合金摩擦磨损性能保持很好的稳定性,因此铜镍锡合金适用在高转速较低载荷的干摩擦工况下。     

不同含量盐水介质中丁腈橡胶水润滑轴承材料摩擦学特性分析

以水润滑轴承用丁腈橡胶(NBR)材料为研究对象,在CBZ-1摩擦磨损试验机上开展其在清水及不同盐分含量水介质中以及不同速度及载荷下的摩擦学试验,对比分析其摩擦因数、磨损量以及磨损表面形貌等摩擦学特性的变化规律。结果表明:盐水质量分数、速度和载荷对丁腈橡胶的摩擦学性能影响显著,其摩擦学特性的变化是盐水质量分数、载荷、速度以及丁腈橡胶的黏弹性等因素共同作用的结果;丁腈橡胶材料与锡青铜配副的摩擦因数随转速的升高而降低,随载荷的增加而降低;随着盐水质量分数的增加,摩擦副的摩擦因数和磨损量先增大而后均有所减小,这是因为盐水质量分数通过影响润滑介质的黏度来改变水润滑的效果,通过对铜盘的腐蚀作用来改变摩擦副的摩擦情况,从而在整体上影响摩擦因数和磨损量的变化。     

船用内燃机轴瓦表面含MoS2的PAI/PTFE聚合物复合涂层制备及减摩抗磨研究

船用内燃机中轴瓦及曲轴工作时接触界面受力复杂，若润滑不当极易造成轴颈的黏着、擦伤、裂纹等。为改善船用内燃机轴瓦的使用寿命，在轴瓦表面制备聚酰胺酰亚胺和聚四氟乙烯（PAI/PTFE）聚合物涂层，并探讨MoS2颗粒对PAI/PTFE复合涂层摩擦性能的影响。通过喷涂-烧结法在轴瓦材料铝锡铜合金表面制备不同MoS2质量分数的复合涂层，并以轴承钢球作为摩擦配副，在3、4、5 N载荷以及干摩擦和油润滑下考察复合涂层的摩擦学性能。结果表明：在干摩擦下，MoS2质量分数为2%的复合涂层摩擦因数降低了80%以上，磨损降低了90%以上；油润滑下摩擦因数最大降低了67%。SEM和EDS分析表明，5 N载荷下，MoS2质量分数低于2%时，长时间摩擦会导致复合涂层破裂，进而产生大的摩擦磨损；而含有2% MoS2的涂层会在钢球接触表面上产生均匀的硫化物层，可以保护涂层提高其稳定性。通过对不同MoS2含量涂层的摩擦因数、磨损及磨痕形貌对比，得出较优的涂层配比。研究表明，适量的MoS2能够提高涂层摩擦膜的稳定性，减小摩擦磨损。     

青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能

在MM-200摩擦磨损试验机上研究了青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能,采用扫描电镜(SEM)对磨损表面形貌进行了观测和采用X射线能谱分析(XPS)分析了涂层成分。结果表明,在水润滑条件下涂层摩擦因数和磨损率均低于干摩擦条件下;在水润滑条件下磨损机制为轻微磨粒磨损和犁削磨损,在干摩擦下主要是较为严重的粘着磨损和犁削。这是由于水润滑降低了摩擦副界面温度,提高了石墨润滑膜的韧性,改善了润滑效果,从而阻止了粘着磨损的发生,水还促进了钢偶件表面致密氧化膜的形成,从而减轻磨损。因此水润滑对涂层磨损性能有较大影响。     

超音速等离子喷涂12Co-WC涂层的组织及在含细沙油润滑条件下的摩擦学性能

为了解决含沙油润滑条件下材料的磨损问题，采用超音速等离子喷涂技术制备了12Co-WC涂层，使用SEM、XRD及T11球盘式摩擦磨损试验机测试了涂层的组织结构及在含细沙油润滑条件下的摩擦学性能。结果 发现由于具有很高的粒子飞行速度，超音速等离子喷涂12Co-WC涂层组织致密，孔隙率小于1％，WC的氧化和分解少，结合强度高，涂层在含细沙油润滑条件下具有良好的摩擦磨损性能，相同条件下的摩擦因数比灰铸铁小，耐磨性比灰铸铁提高4—8倍。     

不同载荷下水润滑高分子材料磨损机制的试验研究

为了研究载荷对新型水润滑高分子轴承材料磨损机制的影响,在CFT-1型摩擦磨损试验机上对该材料进行不同载荷下的无/有水润滑摩擦磨损试验,通过考察试样的摩擦因数、磨痕和磨损表面形貌,分析该材料的磨损机制。结果表明:在无水润滑条件下,该材料的摩擦因数随着载荷的增加呈现先降低后逐渐上升的变化趋势,磨损表面均出现塑性变形和撕裂脱落现象,磨损机制主要为黏着磨损,其中随着载荷的增大表面塑性变形趋于严重,而表面撕裂脱落在中等载荷下较为轻微,在低载荷和高载荷下较为严重;在水润滑条件下,该材料的摩擦因数随着载荷的增加也呈现出先下降低后急剧上升的趋势,磨损表面未发生塑性变形和撕裂脱落,但出现脱落的磨粒和犁沟,磨损机制主要为磨粒磨损,其中在中等载荷下,表面脱落的磨粒少、犁沟细小而浅,在低载荷和高载荷下表面脱落的磨粒多、犁沟深。     

Al2O3-40%TiO2涂层/锡青铜的摩擦磨损性能研究

在室温下对Al2O3-40%TiO2涂层与锡青铜摩擦副进行了油润滑情况下的球盘式摩擦磨损试验。使用SEM分析了磨损表面形貌特性;同时采用EDAX进行了磨损微观区域的成分分析。结果表明:在FD-7主轴润滑油的条件下,A l2O3-40%TiO2涂层与锡青铜之间发生了明显的涂抹和擦伤现象,涂层摩擦磨损性能优异。     

Inconel690合金表面WC-10Co-4Cr和CoCrW涂层的微动磨损特性

为了提高Inconel690合金管的耐磨性,采用超音速火焰喷涂技术(HVOF)在Inconel690合金管表面制备WC-10Co-4Cr和CoCrW两种涂层,在PLINT微动磨损试验机上考察其微动磨损性能。试验结果表明:载荷一定时,涂层的摩擦因数随着位移的增加而变大;相同试验条件下,在稳定阶段,WC-10Co-4Cr和CoCrW涂层的摩擦因数小于Inconel690;两种涂层的耐磨性均显著优于Inconel690合金,而WC-10Co-4Cr涂层的耐磨性略优于CoCrW涂层。磨损表面形貌分析表明,两种涂层的磨痕表面存在剥落坑和剥层现象,磨损机制以剥层和磨粒磨损为主。     

TiAlN涂层往复滑动的摩擦学性能研究

为研究硬质合金表面沉积的TiA lN涂层的摩擦学行为,在不同介质(干态、乳化液、冷却油)条件和试验参数(法向载荷和位移幅值)下,进行了往复滑动摩擦磨损试验。在动力学分析基础上,结合光学显微镜(OM)、激光共焦扫描显微镜(LCSM)、扫描电子显微镜(SEM)和电子能谱(EDS)等微观分析手段对摩擦学性能进行了研究。结果显示:在同样条件下,涂层在试验初期的摩擦因数较小;法向载荷增大,涂层的摩擦因数降低,而位移幅值对涂层摩擦因数的影响不明显;基体的磨损机制主要为磨粒磨损,而涂层剥落是剥层和氧化磨损共同作用的结果;在润滑条件下,涂层的摩擦学性能得到了很大的改善,使涂层寿命得到显著延长,其中冷却油的效果最明显。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

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...     

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。     

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。     

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。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

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.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.