聚合物填充聚四氟乙烯复合材料的摩擦磨损性能

采用机械共混-冷压成型-烧结的工艺制备了PEEK、PPS填充PTFE基粘弹．摩擦型阻尼材料，用环-块式磨损试验机研究了在干摩擦条件下的摩擦磨损性能；用扫描电子显微镜观察磨损表面形貌和内部组织结构。结果表明：混合填充PEEK和PPS时，2种填充物的比例对材料的摩擦因数影响不大，当二者含量相近时，摩擦因数最大；填充物对磨损性能的影响与对摩擦因数的相同；随着PEEK含量的增加和PPS含量的减少，材料的磨损方式由疲劳剥落磨损为主转变为犁削、粘着磨损；PTFE含量的增加，使得复合材料的摩擦因数减小，而磨损有所增大。综合考虑认为，PTFE与适当比例的PEEK／PPS混合填充，具有合适的摩擦因数和较好的耐磨性，能够满足特殊工况下阻尼材料的需要。     

Ekonol/石墨/MoS2填料对PTFE力学和摩擦磨损性能的影响

研究了Ekonol含量对Ekonol／石墨／MoS2／P，PTFE复合材料的力学性能、摩擦磨损性能的影响，以及滑动速度、载荷对材料摩擦磨损性能的影响；用扫描电子显微镜观察了复合材料磨损后的表面形貌，并探讨了其磨损机制。结果表明：加入填料降低了材料的拉伸强度和弯曲强度，但提高了弯曲模量和硬度；同时填料能提高材料的磨损性能，但使摩擦因数升高了；当Ekonol含量较低时，磨损机制为粘着磨损，随着填料含量的增加，Ekonol分散到基体中，起到了承载作用，阻止了PTFE基体的带状破坏，磨损机制为疲劳磨损和轻微的粘着磨损；摩擦因数随载荷的增大而减小，随滑动速度的增大而增大，在相同的滑动时间内，磨痕宽度随载荷和滑动速度的增大而增大。     

聚苯酯填充聚四氟乙烯复合材料的力学及摩擦学性能研究

采用共混-冷压-烧结工艺制备了聚苯酯(POB)填充聚四氟乙烯(PTFE)复合材料,考察了POB含量对PTFE/POB复合材料机械性能和摩擦学性能的影响,探讨了材料的磨损机制和POB的减磨机制.结果表明复合材料的拉伸强度和断裂伸长率随着POB含量的增加而降低,压缩强度随着POB含量的增加而增大;随着POB含量的增加材料摩擦因数呈现增大趋势,POB质量分数在16%～27%范围内材料摩擦因数为0.20～0.24;在与AISI 1045钢的对磨中复合材料发生了黏着磨损,磨损率随着POB质量分数的增加呈现下降趋势,POB质量分数超过25%后继续增加其含量复合材料磨损率降低幅度逐渐变小.     

添加聚四氟乙烯微粉后聚醚醚酮复合材料的摩擦学性能

采用常温机械共混+高温模压方法制备了添加不同含量聚四氟乙烯(PTFE)微粉聚醚醚酮复合材料,研究了其力学性能、摩擦磨损性能及磨损形貌,并探讨了其摩擦磨损机理。结果表明:随PTFE微粉含量的增加,复合材料的洛氏硬度和压缩强度均降低,干摩擦条件下的摩擦因数减小,体积磨损量先降后升,当PTFE微粉质量分数5%时,体积磨损量最低;在油润滑和水润滑条件下复合材料的摩擦因数和体积磨损量均小于干摩擦条件下的,且随PTFE微粉含量的增加,油润滑条件下的体积磨损量下降,而水润滑条件下的增大;在干摩擦条件下复合材料的磨损机制以磨粒磨损为主,并伴有疲劳磨损,在油润滑条件下复合材料表面存在少量片状PTFE磨屑和碳纤维富集,在水润滑条件下复合材料表面被PTFE微片层覆盖,局部存在微裂纹和孔洞。     

纳米Fe3O4填充聚四氟乙烯摩擦磨损性能的研究.doc

利用机械共混、冷压成型和烧结工艺制备不同含量的磁性纳米Fe3O4填充聚四氟乙烯(PTFE)复合密封材料,采用MM 200型摩擦磨损试验机考察其在干摩擦下与45#钢对磨时的摩擦磨损性能,借助扫描电子显微镜（SEM）对磨损表面形貌进行观察并分析磨损机制。结果表明：随磁性纳米Fe3O4含量的增加,复合材料的硬度显著提高,摩擦因数呈现先增大后减小再增大的变化趋势,耐磨性能得到明显改善;当Fe3O4质量分数为15%时,复合密封材料的摩擦因数较小,体积磨损率与纯PTFE相比降低两个数量级;随着Fe3O4含量的增加,磨损机制由纯PTFE的黏着磨损转变为黏着磨损与磨粒磨损共同作用。     

泥沙条件下改性复合材料减振降噪性能研究

为了改善水润滑轴承材料热塑性聚氨酯（TPU）的减振降噪性能,以TPU为基体、聚四氟乙烯（PTFE）为添加剂,通过物理共混的方式制备PTFE/TPU改性复合材料。在RTEC摩擦磨损实验机上模拟泥沙工况,对复合材料进行不同速度和载荷下的摩擦学试验,通过分析复合材料的力学性能、摩擦因数、表面形貌以及振动噪声行为,探讨其摩擦磨损规律与减振降噪性能。结果表明：复合材料的拉伸强度和邵氏硬度均随着PTFE含量的增加而先增加后降低,质量分数8%PTFE改性TPU复合材料表现出最好的力学性能;随着速度与载荷的增大,复合材料的摩擦因数逐渐增大,材料表面损伤、变形、剥落等严重损伤逐渐增多;与纯TPU相比,改性复合材料的摩擦磨损剧烈程度更低,摩擦因数的变化幅度较小且摩擦因数曲线相对光滑,材料微观表面的损伤更少;随着速度与载荷的增大,复合材料的振动响应与辐射噪声现象增大,振动与噪声信号的平均强度增大,频域上的频率分量增多,幅值分量增大,主频向高频转移;PTFE能够改善TPU的摩擦学性能,降低摩擦因数,同时赋予复合材料一定的减振降噪性能,并且效果在高速、高载荷下更为明显。     

聚醚醚酮多元复合材料的摩擦学研究

采用模压法制备了PEEK多元复合材料，用环-块磨损实验机对复合材料进行了磨损试验，用SEM方法对复合材料的磨损表面进行了观察和分析，并利用DSC、红外光谱（FTIR）和SEM分析方法对复合材料的磨屑进行了研究，并探讨了复合材料的磨损机制。结果表明：与PEEK相比，复合材料具有优良的摩擦学性能；PEEK复合材料磨屑的熔点比相应模压材料有所降低，且磨屑的熔限比相应的模压材料有所加宽；随着Ekonol含量的增加，复合材料的磨损机制发生了由粘着磨损为主向疲劳磨损为主的转变；通过磨屑形貌分析和对磨损表面的观察与分析所得的关于复合材料的磨损机制的结论是一致的。     

纳米金属粉填充Ekonol/PTFE复合材料的摩擦磨损性能研究

评价了分别用不同体积含量的纳米镍粉和纳米铜粉填充聚苯酯/聚四氟乙烯(Ekonol/PTFE)复合材料体系的力学性能,利用M-200型磨损试验机研究了纳米Ni、纳米Cu含量对Ekonol/PTFE复合材料摩擦学性能的影响,借助扫描电子显微镜和能谱分析手段考察试样磨损表面和磨屑,并探讨其摩擦磨损机制。结果表明,纳米Ni能在一定范围内增加Ekonol/PTFE复合材料的冲击强度;纳米金属粉填入量较小时均能增加复合材料的洛氏硬度。纳米Ni与纳米Cu均能增加Ekonol/PTFE复合材料的摩擦因数并降低磨损率。其原因在于纳米金属粉在复合材料摩擦表面富集,通过金属分子间的吸引作用,增大复合材料的摩擦因数。     

硬碳填充PTFE复合材料摩擦磨损性能研究

以硬碳为填料制备了PTFE基复合材料,并研究了该复合材料在干摩擦条件下与不锈钢对摩时的摩擦磨损行为,并探讨其磨损机制.实验结果表明:硬碳能提高FIFE硬度,硬碳/PTFE复合材料的耐磨性能明显优于纯PTFE.其摩擦因数随着硬碳含量的增加而减小.复合材料的摩擦表面SEM观察发现:纯PTFE摩擦表面分布着较明显的犁削和粘着磨损的痕迹,硬碳/PTFE的磨痕较浅,表明硬碳作为填料可有效地抑制FTFE的磨损.     

软碳填充PTFE复合材料摩擦磨损性能研究

以不同含量的软碳为填料制备了PTFE基复合材料,测量了其机械性能,在M-2000型摩擦磨损试验机上研究其摩擦磨损行为,并探讨了其磨损机制.结果表明:软碳能提高PTFE复合材料的硬度,软碳/PTFE复合材料的耐磨性能优于纯PTFE,当软碳质量分数为7%时其耐磨性能最好.复合材料的摩擦因数随着软碳含量的增加而增加.摩擦表面的SEM观察发现:纯PTFE的摩擦表面分布着较明显的犁削和黏着磨损的痕迹,复合材料的摩擦表面均出现犁削,随着软碳含量的增加,犁削现象减轻,这表明以软碳作为填料可有效地抑制PTFE的磨损.     

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...     

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。     

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。     

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.     

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.     

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。     

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.     

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....