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Testing development of different surface treatments on pervious concrete

Mina YEKKALAR,Liv HASELBACH,Quinn LANGFITT

《结构与土木工程前沿(英文)》 2016年 第10卷 第4期   页码 385-393 doi: 10.1007/s11709-016-0351-0

摘要: Pervious concrete systems are developing stormwater management technologies which also have wintertime benefits as melting snow may percolate into the system instead of refreezing on the surface. Enhancing the surface microtexture of pervious concrete may also be beneficial in preventing icing or slipping by pedestrians. This research explored different surface treatments on pervious concrete specimens both qualitatively from personal judgements, and quantitatively through static friction measurements with a spring balance with respect to “slipperiness”. The tests were performed on both dry and wet specimens. One aim was to determine whether the spring balance method may be a simple test for comparing surface treatments on pavement samples with little surface area such as laboratory specimens or sidewalk sections. The other purpose was to make a preliminary decision of which surface treatments to use for a sidewalk installation for future studies on wintertime performance. The reliability analysis of the spring balance results showed that there was high operator consistency. In addition, there was a high level of consistency on average results between the quantitative and qualitative methods. This implies that the spring balance test may be an acceptable methodology for comparative analyses with respect to static friction.

关键词: pervious concrete     static coefficient of friction     pedestrian    

微分和表观静摩擦系数的表式

王渭源

《中国工程科学》 2001年 第3卷 第8期   页码 29-32

摘要:

当前,工程师和科学家都对微牛和纳牛量级载荷静摩擦系数(以下简称微牛纳牛静摩擦系数)很感兴趣。但文献中至今没有详细讨论过微牛纳牛静摩擦系数与载荷的关系,而且发表的实验结果都不相互讨论。从微分静摩擦系数的定义出发,导出几种典型模型下微分静摩擦系数和表观静摩擦系数的表式,并据此广泛讨论这些文献中的实验结果。

关键词: 微分静摩擦系数     微牛纳牛静摩擦系数     表观静摩擦系数     宏观静摩擦系数    

Interfacial potential barrier theory of friction and wear

XU Zhongming, DING Lingyun, HUANG Ping, XU Zhongming

《机械工程前沿(英文)》 2008年 第3卷 第3期   页码 276-282 doi: 10.1007/s11465-008-0043-0

摘要: An interfacial potential barrier theory to calculate friction and wear is proposed by considering the micro interaction of frictional surfaces. The theory suggests that the performance of friction and wear depends on the magnitude and distribution of the interfacial potential barrier on contact surfaces. The calculation methods of the interfacial potential barrier and standard interfacial potential barrier are then studied and the formulas to calculate the friction force, friction coefficient, and quantity of adhesion wear are derived based on the theory. With its independence and stability, the standard interfacial potential barrier can be used as an index to describe the frictional performance of materials. The calculation results of the friction force with some existing experimental data are consistent with the experimental results performed with an ultra high vacuum atomic-force microscope, which proves that the theory and method are feasible.

关键词: coefficient     standard interfacial     interaction     formulas     calculation    

Effect of friction coefficients on the dynamic response of gear systems

Lingli JIANG, Zhenyong DENG, Fengshou GU, Andrew D. BALL, Xuejun LI

《机械工程前沿(英文)》 2017年 第12卷 第3期   页码 397-405 doi: 10.1007/s11465-017-0415-4

摘要:

The inevitable deterioration of the lubrication conditions in a gearbox in service can change the tribological properties of the meshing teeth. In turn, such changes can significantly affect the dynamic responses and running status of gear systems. This paper investigates such an effect by utilizing virtual prototype technology to model and simulate the dynamics of a wind turbine gearbox system. The change in the lubrication conditions is modeled by the changes in the friction coefficients, thereby indicating that poor lubrication causes not only increased frictional losses but also significant changes in the dynamic responses. These results are further demonstrated by the mean and root mean square values calculated by the simulated responses under different friction coefficients. In addition, the spectrum exhibits significant changes in the first, second, and third harmonics of the meshing components. The findings and simulation method of this study provide theoretical bases for the development of accurate diagnostic techniques.

关键词: dynamic response     friction coefficient     wind loads     wind turbine gearbox    

超环面行星蜗杆传动摩擦理论研究

许立忠,黄真

《中国工程科学》 2002年 第4卷 第3期   页码 63-67

摘要:

文章通过相对运动关系分析,给出了超环面行星蜗杆传动中共轭运动零件行星轮与定子、行星轮与蜗杆之间相对滑动率的计算方法,得出了凸峰接触时行星轮与定子及蜗杆之间摩擦系数的计算公式;以弹流润滑理论为基础,给出了液体润滑时行星轮与定子及蜗杆之间齿面摩擦系数的计算公式;进而给出了混合摩擦状态下行星轮与定子及蜗杆之间摩擦系数的计算公式。然后,运用上述公式讨论了液体润滑时行星轮与定子及蜗杆之间齿面摩擦系数的相对大小及其随传动参数的变化规律;给出了行星轮与定子全部为凸峰接触时摩擦系数随传动参数的变化规律;讨论了混合摩擦状态下,行星轮与定子之间摩擦系数随膜厚比的变化规律。

关键词: 超环面行星蜗杆传动     摩擦系数     滑动率    

Tribological properties of onion like fullerenes and NiFe

Ruixiang WANG,Yihao ZHANG,Haizhou WU

《能源前沿(英文)》 2021年 第15卷 第1期   页码 208-212 doi: 10.1007/s11708-017-0454-x

摘要: A novel way for a compressor to improve its coefficient of performance and enhance its reliability by employing nano-refrigeration lubricant oil was proposed. Onion like fullerenes (OLFs) and NiFe O nano-composites, modified by Span 80, were dispersed in refrigeration oil KFR22 by solid grinding (SG). Morphologies of NiFe O nano-composites were characterized by using transmission electron microscope (TEM). The tribological properties as a refrigeration lubricants additive were investigated using SRV (II), a multi-functional reciprocating friction and wear tester. The results showed that the friction coefficient was decreased from 0.15 to 0.04.

关键词: refrigeration lubricants     friction coefficient     nano-composites     reciprocating motion     onion like fullerenes    

Performance of rolling piston type rotary compressor using fullerenes (C70) and NiFe

Ruixiang WANG,Yihao ZHANG,Yi LIAO

《能源前沿(英文)》 2020年 第14卷 第3期   页码 644-648 doi: 10.1007/s11708-017-0453-y

摘要: A novel way for a compressor to improve its coefficient of performance was proposed in this paper. Fullerenes (C70) and NiFe O nanocomposites were modified by span 80 and dispersed in refrigeration oil by solid grinding (SG). Besides, the tribological properties of the nanocomposites were investigated using a four ball friction tester. The results show that when the mass concentration of fullerenes nanocomposite is higher than 60 ppm and the concentration of nano-oil is 2 g/L, the friction coefficient decreases from 0.13 to 0.06 which means the wear is reduced. The coefficient of performance of the compressor under the air conditioning test condition can be raised by 1.23%.

关键词: rotary compressor     friction coefficient     nanocomposite materials     coefficient of performance     fullerenes (C70)    

Coulomb-type solutions for passive earth pressure with steady seepage

WANG Junjie, CHAI Hejun, LIN Xin, XU Jiamei

《结构与土木工程前沿(英文)》 2008年 第2卷 第1期   页码 56-66 doi: 10.1007/s11709-008-0001-2

摘要: Present paper deals with the computing of passive earth pressure acting on the vertical rigid retaining wall supporting the soil mass subjected to water seepage. The basic assumptions of Coulomb’s theory and the 2-dimensional steady flow function are used. Three Coulomb-type solutions for the passive earth pressures are presented for the walls provided with three different drainage systems respectively. Based on the general solutions, the variations of the critical inclination of the failure surface and the coefficient of passive earth pressure with increasing the effective friction angle of the soil mass, the soil/structure friction angle, and the water/soil unit weight ratio are discussed. Two tables with values of the coefficients of passive earth pressure for Cases 1 and 3 respectively are also presented.

关键词: function     coefficient     Coulomb-type     effective friction     different drainage    

Dynamical research on spherical micro actuator with piezoelectric ceramic stacks drivers

ZHANG Ruihua, CHEN Haichu

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 433-438 doi: 10.1007/s11465-007-0074-y

摘要: This paper develops a 30 mm × 30 mm × 50 mm spherical micro actuator driven by piezoelectric ceramic stacks (PZT), and analyzes its dynamic performances. First, the space coordinate relationship of the spherical micro actuator and a dynamic model are set up. Second, The Runge-Kutta arithmetic is used to calculate the dynamical parameters of the micro actuator; the SIMULINK module of MATLAB is used to build the dynamical simulating model and then simulate it. Third, an experimental sample of the spherical micro actuator is developed, a micromanipulator is integrated with a micro-gripper based on the sample spherical micro actuator, and the experimental research on the micro assembly is conducted between a micro shaft of 180 μm and a micro spindle sleeve of 200 μm. Finally, the characteristics of the spherical micro actuator influenced by the mass of the metal sphere of the micro actuator, driving signal frequency, friction coefficient of the contact surface between the metal sphere and the friction block of the micro driving unit are analyzed. The experimental results indicate that the rotation resolution of the micro actuator reaches 0.000 1°, the rotation positioning precision reaches 0.000 5°, and the maximum working frequency is about 1200 Hz. The experimental results validate the back rotation vibration model of the spherical micro actuator. The micromanipulator integrated by the spherical micro actuator can meet the requirements of precise micro operation and assembly for micro electro mechanical systems (MEMS) or other microelements in micro degree fields.

关键词: spherical     micro-gripper     friction coefficient     dynamic     frequency    

Analysis of nonlinear channel friction inverse problem

CHENG Weiping, LIU Guohua

《结构与土木工程前沿(英文)》 2007年 第1卷 第2期   页码 205-210 doi: 10.1007/s11709-007-0024-0

摘要: Based on the Backus-Gilbert inverse theory, the singular value decomposition (SVD) for general inverse matrices and the optimization algorithm are used to solve the channel friction inverse problem. The resolution and covariance friction inverse model in matrix form is developed to examine the reliability of solutions. Theoretical analyses demonstrate that the convergence rate of the general Newton optimization algorithm is in the second-order. The Wiggins method is also incorporated into the algorithm. Using the method, noise can be suppressed effectively, and the results are close to accurate solutions with proper control parameters. Also, the numerical stability can be improved.

关键词: singular     SVD     second-order     covariance     Theoretical    

铝合金AA5182-O自冲摩擦铆焊与自冲铆接工艺比较研究 Article

马运五, 山河, 牛嗣哲, 李永兵, 林忠钦, Ninshu Ma

《工程(英文)》 2021年 第7卷 第12期   页码 1741-1750 doi: 10.1016/j.eng.2020.06.015

摘要:

本文分别采用自冲铆接(SPR)和自冲摩擦铆焊(F-SPR)工艺连接铝合金AA5182-O。从接头宏观形貌、铆接力、显微硬度分布、准静态力学性能和疲劳性能等方面对两个工艺进行了系统比较。研究结果表明,FSPR工艺不仅在铆钉与板材之间形成了机械互锁,而且还实现了固相连接;而SPR工艺仅实现了机械互
锁。F-SPR 工艺在摩擦热软化的作用下,获得相同机械互锁所需的铆接力比SPR工艺降低了63%。随着F-SPR 模式转换深度的降低,铆钉周围铝合金加工硬化程度增加。当模式转换深度小于3.0 mm时,FSPR接头比SPR接头具有更高的铝合金硬度。F-SPR 接头中的固相连接和较高的铝合金硬度有效提升了接头的刚度和抗剪切能力,从而使接头的准静态拉剪强度和疲劳寿命与SPR接头相比均有显著提升。

关键词: 自冲铆接     自冲摩擦铆焊     机械连接     准静态强度     疲劳    

Effects of leakage and friction on the miniaturization of a Wankel compressor

Yilin ZHANG, Wen WANG

《能源前沿(英文)》 2011年 第5卷 第1期   页码 83-92 doi: 10.1007/s11708-010-0125-7

摘要: This paper presents a numerical simulation of the performance of a meso-scale Wankel compressor and discusses the factors affecting its miniaturization. The discussion is related to the effect of leakage and friction on the design limit (cooling capacity and dimension) of the meso Wankel compressor. In the simulation, the main leakage comes from the gaps between the rotor and the endplates as well as between the seal apex and the cylinder. The largest friction originates from the clearance among the end face of the eccentric shaft, the end faces of the rotor, and the endplates. The decreasing cooling capacity of the meso Wankel compressor increases the proportion of leakage to displacement and causes the coefficient of performance COP and the mechanical efficiency to decrease. The rational design cooling capacity limit for the meso-scale Wankel compressor is approximately 4 W.

关键词: meso-scale     Wankel compressor     leakage     friction    

A multi-probe micro-fabrication apparatus based on the friction-induced fabrication method

Zhijiang WU, Chenfei SONG, Jian GUO, Bingjun YU, Linmao QIAN

《机械工程前沿(英文)》 2013年 第8卷 第4期   页码 333-339 doi: 10.1007/s11465-013-0276-4

摘要:

A novel multi-probe micro-fabrication apparatus was developed based on the friction-induced fabrication method. The main parts of the apparatus include actuating device, loading system, and control system. With a motorized linear stage, the maximum fabrication area of 50 mm × 50 mm can be achieved, and the maximum sliding speed of probes can be as high as 10 mm/s. Through locating steel micro balls into indents array, the preparation of multi-probe array can be realized by a simple and low-cost way. The cantilever was designed as a structure of deformable parallelogram with two beams, by which the fabrication force can be precisely controlled. Combining the friction-induced scanning with selective etching in KOH solution, various micro-patterns were fabricated on Si(100) surface without any masks or exposure. As a low-cost and high efficiency fabrication device, the multi-probe micro-fabrication apparatus may encourage the development of friction-induced fabrication method and shed new light on the texture engineering.

关键词: friction-induced fabrication     silicon     surface texture     friction     multi-probe    

Damage detection in beam-like structures using static shear energy redistribution

《结构与土木工程前沿(英文)》 2022年 第16卷 第12期   页码 1552-1564 doi: 10.1007/s11709-022-0903-4

摘要: In this study, a static shear energy algorithm is presented for the damage assessment of beam-like structures. According to the energy release principle, the strain energy of a damaged element suddenly changes when structural damage occurs. Therefore, the change in the static shear energy is employed to determine the damage locations in beam-like structures. The static shear energy is derived from the spectral factorization of the elementary stiffness matrix and structural deflection variation. The advantage of using shear energy as opposed to total energy is that only a few deflection data points of the beam structure are required during the process of damage identification. Another advantage of the proposed approach is that damage detection can be performed without establishing a structural finite-element model in advance. The proposed technique is first validated using a numerical example with single, multiple, and adjacent damage scenarios. A channel steel beam and rectangular concrete beam are employed as experimental cases to further verify the proposed approach. The results of the simulation and experiment examples indicate that the proposed algorithm provides a simple and effective method for defect localization in beam-like structures.

关键词: damage detection     beam structure     strain energy     static displacement variation     energy damage index    

地基土上水工建筑物的抗滑动稳定研究(续)

周君亮

《中国工程科学》 2011年 第13卷 第9期   页码 22-30

摘要:

研究地基土上水工建筑物抗滑稳定中存在的问题。利用在基坑内压板抗滑动试验成果,确定地基土回弹影响后的抗滑承载能力降低数值,定量确定地基土抗滑剪应力包线和抗滑摩擦系数;提出采用地基土承受偏心荷载的最大压应力σmax预测建筑物位移、滑动和地基土蠕变滑动的设计方法;确定地基土蠕变滑动轮廓;限定地基土的最大压应力等。按拟定方法回顾计算两座已建水工建筑物,成果符合实物工况。

关键词: 压板抗滑试验     剪应力强度包线     摩擦系数     位移与滑动形式     蠕变滑动     设计计算方法    

标题 作者 时间 类型 操作

Testing development of different surface treatments on pervious concrete

Mina YEKKALAR,Liv HASELBACH,Quinn LANGFITT

期刊论文

微分和表观静摩擦系数的表式

王渭源

期刊论文

Interfacial potential barrier theory of friction and wear

XU Zhongming, DING Lingyun, HUANG Ping, XU Zhongming

期刊论文

Effect of friction coefficients on the dynamic response of gear systems

Lingli JIANG, Zhenyong DENG, Fengshou GU, Andrew D. BALL, Xuejun LI

期刊论文

超环面行星蜗杆传动摩擦理论研究

许立忠,黄真

期刊论文

Tribological properties of onion like fullerenes and NiFe

Ruixiang WANG,Yihao ZHANG,Haizhou WU

期刊论文

Performance of rolling piston type rotary compressor using fullerenes (C70) and NiFe

Ruixiang WANG,Yihao ZHANG,Yi LIAO

期刊论文

Coulomb-type solutions for passive earth pressure with steady seepage

WANG Junjie, CHAI Hejun, LIN Xin, XU Jiamei

期刊论文

Dynamical research on spherical micro actuator with piezoelectric ceramic stacks drivers

ZHANG Ruihua, CHEN Haichu

期刊论文

Analysis of nonlinear channel friction inverse problem

CHENG Weiping, LIU Guohua

期刊论文

铝合金AA5182-O自冲摩擦铆焊与自冲铆接工艺比较研究

马运五, 山河, 牛嗣哲, 李永兵, 林忠钦, Ninshu Ma

期刊论文

Effects of leakage and friction on the miniaturization of a Wankel compressor

Yilin ZHANG, Wen WANG

期刊论文

A multi-probe micro-fabrication apparatus based on the friction-induced fabrication method

Zhijiang WU, Chenfei SONG, Jian GUO, Bingjun YU, Linmao QIAN

期刊论文

Damage detection in beam-like structures using static shear energy redistribution

期刊论文

地基土上水工建筑物的抗滑动稳定研究(续)

周君亮

期刊论文