弹性金属塑料复合材料的摩擦磨损特性研究

在MPX-2000摩擦磨损试验机上，用环盘摩擦副，结合扫描电镜分别评价了弹性金属塑料（EMP）复合材料与钢在油润滑和干摩擦条件下的摩擦磨损特性。结果表明：两种试验条件下，相同滑动速度的摩擦系数随载荷的升高而减小，当载荷为2000N，滑动速度小于3.52m/s时，摩擦系数基于趋于稳定，EMP磨损率随滑动速度和载荷的升高耐增加，但不同试验条件的增幅不高，油润滑下滑动速度小于3.52m/s和干摩擦条件下滑动速度小于1.96m/s时，EMP以微切削，塑性变形和梨沟磨损为主，并在摩擦副两表面形成转移物。     

Ni-Mo-P-Si3N4化学镀层的摩擦磨损性能研究

Q215碳素钢表面上制备一层Ni-Mo-P-Si3N4复合镀层,在MS-T3000摩擦磨损试验机上进行摩擦磨损试验,记录平均摩擦系数,测试磨痕宽度,计算磨损率,研究该化学镀层的摩擦磨损性能。分析结果表明:载荷不变时,平均摩擦系数和磨损率均随滑动速度的增大而增大;滑动速度不变时,平均摩擦系数和磨损率均随载荷的增大而增大;载荷和滑动速度不变时,平均摩擦系数和磨损率随镀层中Si3N4的体积分数先增大后减小。     

聚四氟乙烯工程材料的摩擦磨损性能研究

用MPV-200型摩擦磨损试验机研究了干摩擦条件下磨损时间、滑动速度、载荷、填料等对聚四氟乙烯(PTFE)工程塑料摩擦磨损性能的影响，结果表明：PTFE材料的摩擦因数和磨损率先随速度的增大而减小，然后又随着速度的增大而增大；随磨损时间的增长而降低，最后趋于稳定值；另外，摩擦因数大体上随载荷的增大而减小，磨损量则随载荷的增大而增加；填料可将PTFE的磨损量降低2个数量级，其中石墨使PTFE的摩擦因数降低，玻璃纤维和碳纤维则增大了PTFE的摩擦因数，而MoS2对PTFE摩擦因数的影响较小。对PTFE工程塑料的摩擦磨损特性进行系统分析，为优化设计提供理论基础。     

短切玻璃纤维增强尼龙材料的摩擦与磨损

在环块式磨损试验机上研究了载荷、速度以及润滑介质等因素对自制短切玻璃纤维增强尼龙材料摩擦学行为的影响 ,利用扫描电镜对其磨损机理进行分析。发现 :材料的摩擦系数随载荷的增加而下降 ,达到最小值后 ,又随载荷的增加而持续上升 ,随着速度的增加 ,材料的摩擦系数增加 ;材料的磨损量则随载荷、速度的增加而持续增加 ;材料的磨损以粘着、疲劳为主。在润滑条件下 ,复合材料的摩擦系数大大降低 ;油润滑条件下 ,材料基本无磨损 ,但水润滑条件下 ,材料的磨损量反而比干摩擦条件下大。     

基于田口方法的PEEK/AISI 630在海水环境中的磨损敏感性试验研究

海水液压元件摩擦副材料的表面粗糙度、接触载荷、滑动速度等因素对其摩擦磨损性能具有重要影响,而各因素之间又存在着摩擦磨损交互作用。基于田口方法对PEEK/AISI 630摩擦副进行摩擦磨损试验设计,研究了摩擦副的表面粗糙度、接触载荷和滑动速度对其磨损交互性、敏感性的影响。采用极差分析确定3因素在PEEK/AISI 630摩擦学行为中的相互关系和影响主次顺序;利用方差分析得到3因素对摩擦系数、磨损率影响的显著程度和贡献率;最后,对试验数据进行回归分析,从而获得表面粗糙度、接触载荷、滑动速度分别与摩擦系数、体积磨损量之间的经验公式(又称回归方程),并对回归模型进行可靠性分析。     

芳纶-玻纤混杂纤维增强摩阻材料的研究

以丁腈橡胶改性酚醛树脂作为树脂基体,芳纶纤维-玻璃纤维混杂纤维作为变量,经热压烧结制备出一种混杂纤维增强摩阻材料。在干摩擦条件下通过摩擦磨损试验机测试其摩擦学性能。经实验表明:材料的摩擦系数随着载荷、滑动速率的增大整体呈现减小趋势,磨损率随着载荷的增加出现波动,随滑动速率的增大呈现减小的趋势。在不同载荷和滑动速率条件下,含有芳纶/玻纤混杂纤维增强摩阻材料表现出较好的摩擦学性能。摩擦过程中,含有芳纶-玻纤混杂纤维的摩阻材料磨损形式为犁沟和塑性变形,未含有的磨阻材料磨损形式主要为疲劳磨损。     

干摩擦和水润滑条件下单晶硅的摩擦磨损性能研究

在UMT-2微摩擦试验机上,对单晶硅片进行了干摩擦和水润滑两种状态下的摩擦磨损试验,分析讨论了载荷和滑动速度对单晶硅片的摩擦因数和磨损率的影响规律;运用扫描电子显微镜,观察和分析了其磨损表面形貌。结果表明:干摩擦条件下的磨损机理主要表现为黏着磨损,水润滑条件下的磨损机理主要表现为机械控制化学作用下的原子/分子去除过程;水润滑条件下的摩擦因数和磨损量均较小,最小磨损率仅为10μm3/s;在水润滑条件下,载荷和滑动速度达到一定值时,硅片表面将发生摩擦化学反应,生成具有润滑作用的Si(OH)4膜,即机械作用在一定条件下对化学反应具有促进作用。     

WC/TiC层状陶瓷刀具与316L不锈钢间的干摩擦磨损性能研究

研究了在1 750℃下真空热压烧结而成的WC/TiC层状陶瓷刀具材料在干摩擦条件下与316L奥氏体不锈钢之间的摩擦磨损性能,并对磨损面进行了分析。结果表明:载荷和滑动速度对摩擦因数和磨损量的影响较大,随着载荷的不断增大,WC/TiC层状陶瓷刀具材料的摩擦因数和磨损量呈增大趋势;而随着滑动速度的增大,WC/TiC层状陶瓷刀具材料的摩擦因数先降后增,磨损量先增后降;在WC/TiC层状陶瓷刀具材料与316L奥氏体不锈钢的对磨过程中,材料的表面发生了犁削、颗粒及片层剥落现象,在磨损表面留有犁沟、凹坑、微裂纹和片层结构,其磨损机理为磨粒磨损和粘着磨损。     

浸金属碳滑板/铜银合金接触线载流摩擦磨损性能的试验研究

选取地铁刚性接触网中现役的浸金属碳滑板与铜银合金接触线为接触副,模拟地铁弓网的实际运行状况,在环-块式试验机上研究直流电流为200~400 A、法向载荷为15~40 N、滑动速度为40~120 km/h工况下浸金属碳滑板载流摩擦磨损性能。结果表明：摩擦因数随电流和滑动速度的增大而减小,随法向载荷的增大而增大;磨损量随电流和滑动速度的增大而增大,当电流较小时（如200 A）,磨损量和法向载荷之间存在一个阈值,当电流较大时（如400 A）,磨损量随法向载荷的增大而减小;滑板温度随电流的增大而增大,随法向载荷增大而减小,当电流较小时（如200 A）,滑板温度随速度的增大而增大,当电流较大时（如400 A）,滑板温度随速度的增大而减小;当电流为200~300 A时,其磨损机制主要为机械磨损,当电流为300~400 A时,其磨损机制主要为氧化磨损和电弧烧蚀。     

高速摆动下PTFE编织复合材料干摩擦研究

利用高速摩擦试验机对PTFE编织复合材料进行干摩擦试验,研究不同条件(载荷、速度和湿度)下PTFE编织复合材料干摩擦磨损性能;并利用扫描电子显微镜对不同条件下的磨屑形貌进行分析。结果表明:单因素变化条件下,摩擦因数随载荷和相对湿度的增大而减小,随摩擦速度的增大而增大;磨损量随载荷和速度的增大而增大,但相对湿度的增加可降低磨损;载荷及速度的增加显著影响材料磨损状况。     

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...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

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.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.