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基于DISlab系统的摩擦力教学测量仪的设计与研究 预览
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作者 王一超 徐佳林 +2 位作者 郑思怡 张译丹 呼格吉乐 《科技创新与应用》 2019年第16期27-28,共2页
在我们的生活中,摩擦力处处存在而且起着十分重要的作用。在实际的教学过程中,摩擦力的分析一直是教学的难点,对于学生来说,摩擦力的大小和方向只能借助作用效果来分析,会显的十分抽象,不够直观,基于此问题的思考,结合DISlab朗威实验系... 在我们的生活中,摩擦力处处存在而且起着十分重要的作用。在实际的教学过程中,摩擦力的分析一直是教学的难点,对于学生来说,摩擦力的大小和方向只能借助作用效果来分析,会显的十分抽象,不够直观,基于此问题的思考,结合DISlab朗威实验系统制作出了一款摩擦力的测量仪,可以较为直观的展示摩擦力的方向和大小,有助于学生理解和学习摩擦力的相关知识。 展开更多
关键词 摩擦力 滑动摩擦 力的传递 最大静摩擦力 运动情况 DIS实验系统
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Active control of friction by transverse oscillations
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作者 J.BENAD K.NAKANO +1 位作者 V.L.POPOV M.POPOV 《摩擦(英文版)》 CSCD 2019年第1期74-85,共12页
The present paper is devoted to a theoretical analysis of sliding friction under the influence of in-plane oscillations perpendicular to the sliding direction.Contrary to previous studies of this mode of active contro... The present paper is devoted to a theoretical analysis of sliding friction under the influence of in-plane oscillations perpendicular to the sliding direction.Contrary to previous studies of this mode of active control of friction,we consider the influence of the stiffness of the tribological contact in detail and show that the contact stiffness plays a central role for small oscillation amplitudes.In the present paper we consider the case of a displacement-controlled system,where the contact stiffness is small compared to the stiffness of the measuring system.It is shown that in this case the macroscopic coefficient of friction is a function of two dimensionless parameters a dimensionless sliding velocity and dimensionless oscillation amplitude.In the limit of very large oscillation amplitudes,known solutions previously reported in the literature are reproduced.The region of small amplitudes is described for the first time in this paper. 展开更多
关键词 SLIDING FRICTION IN-PLANE OSCILLATION contact STIFFNESS COEFFICIENT of FRICTION active control of FRICTION
收获期谷子叶片摩擦特性的试验研究 预览
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作者 张宁 李红波 +2 位作者 张燕青 崔清亮 孙青芳 《农机化研究》 北大核心 2019年第6期154-161,共8页
为了探明谷子叶片的摩擦特性,降低其对谷子联合收获机割台损失的影响,采用自制摩擦测试装置,联合Instron5544型电子万能试验机,选定谷子张杂10号、晋谷21号和沁州黄等3个品种,分别测定了叶片之间及叶片与不同金属材料接触时的摩擦特性... 为了探明谷子叶片的摩擦特性,降低其对谷子联合收获机割台损失的影响,采用自制摩擦测试装置,联合Instron5544型电子万能试验机,选定谷子张杂10号、晋谷21号和沁州黄等3个品种,分别测定了叶片之间及叶片与不同金属材料接触时的摩擦特性参数。分析了叶片不同方向(纵向和横向)、不同表面(上表面和下表面)、不同倒刺方向(顺纹和逆纹)及不同金属薄板(钢板、铝板、铁板)等因素对叶片摩擦特性的影响规律。试验结果表明:叶片与叶片摩擦时,张杂10号、晋谷21号、沁州黄的静摩擦因数和滑动摩擦因数值范围分别为0.3953~0.9665/0.3695~0.9565、0.3657~0.9467/0.3556~0.8863、0.3570~0.9420/0.3338~0.9088;叶片的方向及倒刺方向两因素对其影响极显著(P<0.01),叶片在横向及逆着倒刺方向时,摩擦因数值较大。叶片与不同金属材料接触时,张杂10号、晋谷21号、沁州黄叶片与不同金属材料板接触时静摩擦因数值和滑动摩擦因数值范围分别为0.2800~0.5865/0.2546~0.4595、0.2625~0.6080/0.2265~0.4595、0.2805~0.4660/0.2676~0.4318;其与铁板的摩擦因数值最高,钢板与铝板次之且无显著差别。研究结果可为谷子收获机械的研制与设计提供一定的技术参数和理论依据。 展开更多
关键词 谷子叶片 摩擦 静摩擦因数 滑动摩擦因数
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石墨烯与MoS2纳米颗粒对PAO40摩擦学性能的影响研究 预览
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作者 金旭阳 杜洋 +1 位作者 张明宇 王静 《青岛理工大学学报》 CAS 2019年第4期104-108,共5页
采用四球摩擦磨损试验机考察了石墨烯与MoS2纳米颗粒添加剂对合成油PAO40的抗磨减摩性能的影响.试验后通过磨斑显微镜观察磨斑形状并用Origin软件处理了摩擦系数和磨斑的表征直径.试验结果显示:只有在特定工况条件下,特定浓度的石墨烯和... 采用四球摩擦磨损试验机考察了石墨烯与MoS2纳米颗粒添加剂对合成油PAO40的抗磨减摩性能的影响.试验后通过磨斑显微镜观察磨斑形状并用Origin软件处理了摩擦系数和磨斑的表征直径.试验结果显示:只有在特定工况条件下,特定浓度的石墨烯和MoS2纳米颗粒添加剂才具有抗磨减摩效果.整体上讲,MoS2纳米颗粒添加剂的抗磨减摩效果要优于石墨烯. 展开更多
关键词 摩擦 四球摩擦磨损试验机 石墨烯 MOS 2 抗磨 减摩
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微坑型微织构硬质合金表面对木材摩擦特性的影响 预览
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作者 李伟光 张占宽 《林业科学》 EI CAS CSCD 北大核心 2019年第4期136-143,共8页
【目的】探讨木材含水率、木材切面和纤维方向以及运动速度等因素对木材表面摩擦系数的影响规律,为设计更加合理的木材切削刀具表面织构形式提供参考和指导。【方法】以水曲柳和樟子松为研究对象,在具有不同微坑直径硬质合金表面条件下... 【目的】探讨木材含水率、木材切面和纤维方向以及运动速度等因素对木材表面摩擦系数的影响规律,为设计更加合理的木材切削刀具表面织构形式提供参考和指导。【方法】以水曲柳和樟子松为研究对象,在具有不同微坑直径硬质合金表面条件下,研究木材含水率、木材切面和纤维方向以及运动速度等因素对木材表面摩擦系数的影响。【结果】与无微坑表面相比,当微坑直径为60μm、含水率为67%±3%时,在水曲柳表面产生的摩擦系数由0.151降低到0.091,降幅为39.7%,在樟子松表面产生的摩擦系数由0.241降低到0.164,降幅为32.0%。木材径切面上纤维方向差异对表面摩擦系数的影响不大,但在横切面上,微坑直径越小,其表现出的摩擦系数越高。摩擦过程中运动速度对表面摩擦系数的影响与木材中的水分有较大关系,当含水率处于生材状态时,表面摩擦系数随运动速度增大而降低,且微坑型结构表面产生的摩擦系数降幅明显高于无微坑表面,无微坑表面产生的摩擦系数由0.160降低到0.134,降幅为16.3%,微坑直径为60μm时的摩擦系数由0.124降低到0.071,降幅为42.7%。【结论】木材含水率状态对微坑型表面微织构与木材之间的摩擦系数影响较大,木材中自由水的存在有利于降低硬质合金与木材表面之间的摩擦系数。微织构直径越小,其接触角平均变化率越大,表面铺展速度越大,越有利于改善木材/硬质合金摩擦副的状态,使表面间的摩擦系数减小。 展开更多
关键词 木材 切削 摩擦 摩擦系数 微织构
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Experimental Study on Secondary Wear of Friction Pair Surface 预览
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作者 Yanqiang Gou Yuhu Yan 《世界工程和技术(英文)》 2019年第3期513-519,共7页
The phenomenon that the hard abrasive grains repeatedly cut the surface material of the parts during wear is very common in wear. In order to study the influencing factors of mechanical damage, based on the three-body... The phenomenon that the hard abrasive grains repeatedly cut the surface material of the parts during wear is very common in wear. In order to study the influencing factors of mechanical damage, based on the three-body abrasive wear, this paper discusses the wear of the secondary cutting abrasive. Firstly, the secondary wear model of the hemispherical abrasive grain on the friction pair surface is established. Secondly, the simulation experiment is carried out on the secondary scratching of the abrasive wear on the surface of the part. Next, the equivalent strain data and the equivalent stress data obtained by the experiment are subjected to secondary friction analysis. The final results show that the secondary friction damage of the hemispherical abrasive grain is greater than one wear. 展开更多
关键词 HEMISPHERICAL ABRASIVE GRAIN WEAR FRICTION
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Principles and application of RES welding technology 预览
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作者 韩立军 于立建 +1 位作者 张更伟 钟丽慧 《中国焊接:英文版》 EI CAS 2019年第2期50-55,共6页
Friction element welding technology is rich of flow drill screws combined with friction welding technology and is developed for the hot-forming steel plate and aluminum alloy welding of car body-in-white.In this paper... Friction element welding technology is rich of flow drill screws combined with friction welding technology and is developed for the hot-forming steel plate and aluminum alloy welding of car body-in-white.In this paper,the principle of RES welding technology,equipment,technical characteristics,application condition and welding parameters are analyzed systematically.Moreover,the changing laws of welding parameters and welded joint quality control standards are described,which provides the necessary technical support for safety and light-weight car body design requirements.This study has high practical application value,and enriches the automobile body joining technology. 展开更多
关键词 FRICTION element WELDING flow DRILL SCREWS FRICTION WELDING aluminum alloy hot-forming steel
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The Island Rule with lateral and bottom friction 预览
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作者 Yanzhao Yang Zexun Wei +2 位作者 Guanlin Wang Zhan Lian Liwei Wang 《海洋学报:英文版》 SCIE CAS CSCD 2019年第4期146-153,共8页
The Island Rule,derived from the Sverdrup theory,is widely used to estimate and analyze water transport through a strait.Previous studies presented single-or multi-island rules with either lateral or bottom friction.I... The Island Rule,derived from the Sverdrup theory,is widely used to estimate and analyze water transport through a strait.Previous studies presented single-or multi-island rules with either lateral or bottom friction.In this paper,an analytical model of wind-driven circulation is assumed based on linear dynamics.Considering both lateral and bottom friction,the analytic solutions of the transport streamfunction around the islands are derived and the volume transport through the channel is presented.The results are similar to those of Wajsowicz,but the frictional constants represent different values.The analytic solution shows that the relationship between the lateral frictional and bottom frictional dissipation is complex in terms of the frictional constants.To understand the interaction between the two friction types,lateral and bottom friction values were randomly chosen on a barotropic beta plane.The result shows an approximately linear relationship between the lateral and bottom friction in consisting of the combined frictional constants.We studied the effect of the channel width on the transport through the channel.The results show that the friction enhances the flow under some widths,which is similar to the flow behavior when only the lateral friction is considered.We also compared the transport through the channel at different depths and founded that the deeper the water,the smaller the transport reduction ratio when the horizontal eddy viscosity coefficient and the bottom drag coefficient remained constants.To further present the combined role of lateral frictional and bottom frictional dissipation,we compared our model with the model of Wajsowicz for two islands,where only the lateral or bottom friction were considered,with different channel widths.The results showed that the effect of the lateral friction is greater than the bottom friction when the channel is narrow,especially in the Munk boundary layer thickness.When the channel is much wider than the Munk boundary layer thickness,the role of the bottom 展开更多
关键词 ISLAND RULE LATERAL FRICTION BOTTOM FRICTION TRANSPORT streamfunction
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Friction and Deformation Behavior of Elastomers 预览
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作者 Alexander Adam Dominik Paulkowski Bernd Mayer 《材料科学与应用期刊(英文)》 2019年第8期527-542,共16页
This research paper is about investigating the mechanisms of elastomeric friction at low velocities. To do so, different experimental setups were performed to analyze friction, adhesion and surface energy among others... This research paper is about investigating the mechanisms of elastomeric friction at low velocities. To do so, different experimental setups were performed to analyze friction, adhesion and surface energy among others. The tested materials were EPDM samples with variations in the carbon black content. It was found, that at least for low velocities, the real contact area has the main impact on the friction of elastomers. This contact area seems to be highly influenced by the hardness or other bulk properties of the elastomers, which are modified by the varying carbon black content. 展开更多
关键词 Elastomers FRICTION ADHESION TRIBOLOGY Carbon BLACK VARIATION Contact Area
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Friction
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《摩擦(英文版)》 CSCD 2019年第5期497-499,共3页
Aims and Scope Friction is a peer-reviewed international journal for the publication of theoretical and experimental research works related to the friction,lubrication and wear.Original,high quality research papers an... Aims and Scope Friction is a peer-reviewed international journal for the publication of theoretical and experimental research works related to the friction,lubrication and wear.Original,high quality research papers and review articles on all aspects of tribology are welcome,including,but are not limited to,a variety of topics,such as:Friction:Origin of friction,Friction theories,New phenomena of friction,Nano-friction,Ultra-low friction,Molecular friction,Ultra‐high friction,Friction at high speed,Friction at high temperature or low temperature,Friction at solid/liquid interfaces,Bio‐friction,Adhesion,etc. 展开更多
关键词 FRICTION AIMS SCOPE FRICTION
织造中碳纤维束间的摩擦磨损试验模拟 预览
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作者 杨洁 吴宁 +3 位作者 李帅 解锡明 焦亚男 陈利 《摩擦学学报》 EI CAS CSCD 北大核心 2019年第1期90-98,共9页
织造过程中碳纤维束的摩擦磨损会导致成型后复合材料制件的机械性能下降.采用自制的试验装置模拟织造过程中经纬纱线间的相互作用,研究了法向负载、预加张力和摩擦速率对碳纤维束摩擦磨损行为的影响.结果表明:碳纤维束的摩擦系数随着法... 织造过程中碳纤维束的摩擦磨损会导致成型后复合材料制件的机械性能下降.采用自制的试验装置模拟织造过程中经纬纱线间的相互作用,研究了法向负载、预加张力和摩擦速率对碳纤维束摩擦磨损行为的影响.结果表明:碳纤维束的摩擦系数随着法向负载的增加而减小,其磨损程度随着法向负载的增加而增大,相对应的碳纤维束拉伸断裂强力也逐渐下降;碳纤维束的摩擦力和摩擦系数因实际摩擦接触面积的变化随预加张力的增加而增大;摩擦速率的增加几乎不影响碳纤维束的摩擦力和摩擦系数,但延长了其测试值达到稳定所需的周期数. 展开更多
关键词 碳纤维 织造 摩擦 磨损 法向负载 预加张力 摩擦速率
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Theoretical Model and Experimental Research on Friction and Torque Characteristics of Hydro-viscous Drive in Mixed Friction Stage 预览
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作者 Hongwei Cui Qiliang Wang +1 位作者 Zisheng Lian Long Li 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2019年第5期59-69,共11页
The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque c... The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque characteristics of friction pairs are very complex and change at any time.The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage.The fluid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory.In addition,the contact friction coefficient of the friction pairs was taken into consideration and measured by using the MM1000-Ⅲfriction and wear testing machine.The asperity friction torque and total torque in the mixed friction stage were obtained and finally,the test rig for the torque characteristics was set up.The results show that the contribution to the total torque is shared by the oil film and the asperity friction.The friction coefficient decreases sharply at first and then increases with a change in the relative rotational speed,following the Stribeck curve closely,and the contact frictional coefficient slowly decreases with increase in the pressure between the friction pairs.The torque between the friction pairs is provided by the asperity friction,and the torque due to the oil film reduces to zero.When the thickness of the oil film is small,a major contribution to the total torque is due to the asperity friction.The total torque also increases with the decrease in the film thickness ratio.Therefore,by theoretical analysis and experimental verification,the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model. 展开更多
关键词 Hydro-viscous drive(HVD) Mixed friction stage Torque characteristics Contact friction coefficient
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Cr2AlC含量对铜基复合材料摩擦磨损性能的影响
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作者 吴辉 郭彪 +3 位作者 李强 敖进清 刘胜明 鲁云 《粉末冶金技术》 CAS CSCD 北大核心 2019年第3期184-190,共7页
采用冷压-烧结方法制备了含质量分数0%、5%、10%、15%Cr2AlC的铜基复合材料,利用光学显微镜、扫描电子显微镜及能谱仪观察并分析复合材料微观组织和微区成分,使用HVS-1000型显微硬度计和M-2000型摩擦磨损试验机测试复合材料的硬度和摩... 采用冷压-烧结方法制备了含质量分数0%、5%、10%、15%Cr2AlC的铜基复合材料,利用光学显微镜、扫描电子显微镜及能谱仪观察并分析复合材料微观组织和微区成分,使用HVS-1000型显微硬度计和M-2000型摩擦磨损试验机测试复合材料的硬度和摩擦磨损性能,分析Cr2AlC质量分数对复合材料硬度、摩擦性能和磨损机理的影响。结果表明:含Cr2AlC铜基复合材料的相对密度为0.8,Cr2AlC均匀分布在铜基体上,有效提高了复合材料的硬度;随Cr2AlC质量分数增加,复合材料摩擦系数先升高后降低,磨损量先降低后回升,当Cr2AlC质量分数为10%时,复合材料的摩擦系数最大,磨损量最低,耐磨性能最佳;未添加Cr2AlC的纯铜材料磨损机理以黏滑为主,含Cr2AlC铜基复合材料的磨损机理是犁削磨损、剥层磨损和氧化磨损三者的结合。 展开更多
关键词 铜基复合材料 硬度 摩擦 磨损 摩擦系数
塔磨机橡胶磁性衬板的吸附力研究
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作者 刘万华 于忠淇 赵骞 《矿山机械》 2019年第4期31-34,共4页
对塔磨机橡胶磁性衬板的磁吸附力进行了研究,通过悬挂重物法,测量出不同材质的磨球在衬板表面的吸附力,再用Ansoft有限元软件,模拟分析了衬板表面磁感应强度分布规律,并计算出衬板与筒体之间的摩擦因数为0.47,最后拟合出橡胶磁性衬板和... 对塔磨机橡胶磁性衬板的磁吸附力进行了研究,通过悬挂重物法,测量出不同材质的磨球在衬板表面的吸附力,再用Ansoft有限元软件,模拟分析了衬板表面磁感应强度分布规律,并计算出衬板与筒体之间的摩擦因数为0.47,最后拟合出橡胶磁性衬板和筒体之间的吸附力与磁极厚度的关系。该研究对大型塔磨机在磁铁矿中的应用具有重要的参考和借鉴价值。 展开更多
关键词 塔磨机 橡胶磁性衬板 吸附力 摩擦力 摩擦因数
Experimental study on the tribo-chemical smoothening process between self-mated silicon carbide in a water-lubricated surfacecontact reciprocating test
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作者 Le JIN Herbert SCHEERER +2 位作者 Georg ANDERSOHN Matthias OECHSNER Dieter HELLMANN 《摩擦(英文版)》 CSCD 2019年第2期181-191,共11页
Silicon carbide(SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment.As well reported in the point-contact tests,this smoothening process works well due to the abund... Silicon carbide(SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment.As well reported in the point-contact tests,this smoothening process works well due to the abundant water as oxidant.After this smoothening process,the tribo-surface is well polished,a closely mated tribo-gap naturally forms,and an ultra-low friction state is built.However,water in the tribo-gap could be insufficient in industrial applications,e.g.,the seal gap in mechanical seals.In this study,the tribo-chemical smoothening behavior in such environment was researched.A surface-contact reciprocating test was used to simulate the aqueous environment where water was insufficient.After tests,compared to the published results from the point-contact tests,the same ultra-low friction state was achieved.A part of the tribo-surface was tribo-chemically smoothened.The obtained smoothened surface microstructure was consistent with the published information.Meanwhile,severe abrasive wear occurred.A porous oxygen-rich layer was found existing beneath the abrasion-induced grooves,in which numerous smashed wear debris adhered on the worn surfaces.We concluded that the shortage of water initiated the severe abrasion,meanwhile the generated wear debris aggravated the wear condition.This understanding is instructive for developing new methods to avoid the severe abrasion in the same water insufficient environment. 展开更多
关键词 silicon CARBIDE surface-contact SLIDING FRICTION tribo-chemical smoothening ABRASION ultra-low FRICTION mechanical seal
基于遗传算法辨识的进给伺服系统摩擦特性研究 预览
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作者 张健 《农业装备与车辆工程》 2019年第3期78-82,共5页
因为直线进给伺服系统容易受到摩擦力的影响,对于以高速高精度直线电机为组成核心的进给系统,消除摩擦力的影响尤为重要。因此,本文以直线电机导轨的摩擦力为研究对象,基于能反映摩擦过程中动静态特性的LuGre摩擦模型,考虑了摩擦迟滞非... 因为直线进给伺服系统容易受到摩擦力的影响,对于以高速高精度直线电机为组成核心的进给系统,消除摩擦力的影响尤为重要。因此,本文以直线电机导轨的摩擦力为研究对象,基于能反映摩擦过程中动静态特性的LuGre摩擦模型,考虑了摩擦迟滞非线性因素的影响。以单轴直线电机进给系统为实验平台,通过LabVIEW构建摩擦力实验测试平台,经过与MATLAB交互的小波去噪算法的滤波后得到摩擦力数据。利用遗传算法的摩擦模型参数辨识方法有效地对模型参数进行了参数辨识。该方法得到的结果与通过实验得到的数据具有一致性,验证了方法的正确性与辨识结果的准确性。 展开更多
关键词 直线电机 摩擦力 小波去噪 遗传算法 参数辨识
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Water-based superlubricity in vacuum
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作者 Chen XIAO Jinjin LI +6 位作者 Lei CHEN Chenhui ZHANG Ningning ZHOU Tao QING Linmao QIAN Jiyang ZHANG Jianbin LUO 《摩擦(英文版)》 CSCD 2019年第2期192-198,共7页
This study achieved water‐based superlubricity with the lubrication of H3PO4 solution in vacuum(highest vacuum degree <10^–4 torr) for the first time by performing a pre‐running process in air before running in ... This study achieved water‐based superlubricity with the lubrication of H3PO4 solution in vacuum(highest vacuum degree <10^–4 torr) for the first time by performing a pre‐running process in air before running in vacuum.The stable water‐based superlubricity was sustainable in vacuum(0.02 torr) for 14 h until the test was stopped by the user for non‐experimental factor.A further analysis suggested that the superlubricity may be attributed to the phosphoric acid–water network formed in air,which can efficiently lock water molecules in the liquid lubricating film even in vacuum owing to the strong hydrogen bond interaction.Such capability to lock water is strongly affected by the strength of hydrogen bond and environmental conditions.The realization of water‐based superlubricity with H3PO4 solution in vacuum can lead to its application in space environment. 展开更多
关键词 FRICTION WATER-BASED SUPERLUBRICITY VACUUM phosphoric ACID
Discharge Coefficient Measurements Using Heron's Fountain 预览
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作者 Gevo Abcarian Zainab Algharib +5 位作者 Omran Hussain Ana Martin Abraham Villa Francisco Villalobos Tadeh Zirakian David Boyajian 《土木工程与建筑:英文版》 2019年第3期195-203,共9页
Civil Engineering design students at CSUN (California State University, Northridge), aimed to demonstrate the pneumatic action of liquid water as it flows through an airtight one-way vessel system which is known as He... Civil Engineering design students at CSUN (California State University, Northridge), aimed to demonstrate the pneumatic action of liquid water as it flows through an airtight one-way vessel system which is known as Heron’s Fountain. This project explores hydraulic and pneumatics principles commonly found in environment control systems, such as the non-isothermal heating facilities located on the CSUN campus. Since this was a simply constructed version of an ancient Greek fountain, its development required the collaboration of the team to execute its simple function. The parameters involved were diameter, length, height, and density. This analysis utilizes Pascal and Bernoulli’s equations to reinforce the principles of fluid mechanics. The fountain action is described based on flow rate and head loss is described by Darcy’s equation. Friction loss with an angled fitting attached to the fountain head is described by Reynold’s equation. The experiment observed the performances of two types of reentrant tube fittings for head loss: straight and angled. The experiment enhanced the educational experience of the research team by bringing together creative ideas from different educational and cultural backgrounds. The results of the experiment concluded with a 0.58% error for the straight fitting and 5.3% error for an angled fitting. 展开更多
关键词 Heron's FOUNTAIN HYDRAULIC PRINCIPLES air pressure PNEUMATICS FRICTION factor engineering education
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高温条件下Fe(Cr)-B合金的摩擦学性能 预览
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作者 崔功军 杨振伟 +1 位作者 王文杰 高贵军 《中南大学学报:英文版》 SCIE EI CAS CSCD 2019年第10期2643-2650,共8页
本文研究了在室温至800℃范围内硼元素及其含量(0 wt%, 5 wt%, 7 wt%和 9 wt%)对 Fe-Cr-B 合金抗磨性能的影响,并以此为依据拓宽其作为高温抗磨原件的应用。另外,探讨了合金的高温磨损机理。在室温到 800 ℃ 范围内,当滑动速度为 0.20 m... 本文研究了在室温至800℃范围内硼元素及其含量(0 wt%, 5 wt%, 7 wt%和 9 wt%)对 Fe-Cr-B 合金抗磨性能的影响,并以此为依据拓宽其作为高温抗磨原件的应用。另外,探讨了合金的高温磨损机理。在室温到 800 ℃ 范围内,当滑动速度为 0.20 m/s 且载荷为 10 N 时,以氮化硅陶瓷球作为摩擦 副,采用球-盘式高温摩擦实验机系统研究了试样的高温摩擦学性能。相比于不含硼元素的试样,添加硼元素试样的抗磨损性能得到了极大的改善。合金的摩擦系数随着测试温度的升高而降低。随着金属中硼含量的增加 Fe-Cr-B 合金的磨损率开始降低,然后开始升高。含硼的铁基合金的磨损率是不含硼的铁基合金的磨损率的 1/10。在高温条件下,Fe-21wt%Cr-7wt%B 合金具有最好的摩擦学性能。 展开更多
关键词 Fe(Cr)-B 合金 复合材料 高温摩擦性能 摩擦 抗磨损性能
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基于摩擦力的机械臂零重力系统卸载性能
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作者 田斯慧 唐晓强 +1 位作者 代海林 李煜琦 《清华大学学报:自然科学版》 EI CAS CSCD 北大核心 2019年第10期831-837,共7页
空间机械臂在地面零重力系统进行模拟实验前,需先用装有传感器的模拟机械臂对模拟系统的卸载性能进行评定,以保证系统工作时的可靠性。该文首先建立了一个七关节机械臂在地面零重力系统中的动力学模型,计算了各关节扭矩,并以扭矩作为模... 空间机械臂在地面零重力系统进行模拟实验前,需先用装有传感器的模拟机械臂对模拟系统的卸载性能进行评定,以保证系统工作时的可靠性。该文首先建立了一个七关节机械臂在地面零重力系统中的动力学模型,计算了各关节扭矩,并以扭矩作为模拟系统卸载性能的评价指标。接着采用连续性摩擦模型对系统进行摩擦力参数辨识,通过实验结果反推出系统的摩擦力特性,并对关节扭矩进行修正。修正后的计算扭矩更接近实验值,保证了理论建模的准确性。该模型可以预测出未安装传感器的空间机械臂在模拟系统中运行时的力学参数,保证实验的安全。 展开更多
关键词 空间机械臂 零重力模拟系统 关节扭矩 摩擦力
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