检索结果-南通市图书馆

Acta Mechanica Solida Sinica 2021年第5期34卷 754-765页

作者： Ling Li Jingjing Wang Xiaohui Shi Meijuan Tong Lixia Li School of Mechanical and Electrical Engineering Xi’an University of Architecture and TechnologyXi’an710055China

The contact stiffness of the joint surface directly affects the static and dynamic mechanical behavior,and accuracy of the machine tool.A new elastoplastic contact stiffness model is proposed by considering continuous and smooth contact characteristics and substrate ***,the interpolation interval of cubic Hermite polynomials is improved to meet the continuous and smooth change of contact parameters during asperity ***,the micro-contact mechanism considering substrate deformation is explored by establishing an asperity-substrate system ***,combined with statistical principles,a new contact stiffness model of the joint surface is ***,the correctness of the built model is verified by comparing with experimental data and different contact *** simulation results show that the model changes continuously and smoothly in the three deformation *** substrate deformation mainly affects the asperities in the elastic contact *** smoother is the surface,the more significant is the influence of substrate deformation.

关键词： Joint surface contact stiffness Continuous smooth contact characteristics Substrate deformation

NORMAL contact stiffness OF THE ELLIPTIC AREA BETWEEN TWO ASPERITIES

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2015年第1期28卷 33-39页

作者： Zhiqiang Liu Junping Shi Fusheng Wang Zhufeng Yue School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Department of Engineering Mechanics School of Science Xi'an University of Technology

A new expression for contact deformation is given, and the normal contact stiff- ness between single asperities is derived according to Hooke＇s law. A contact model between two ellipsoidal asperities is simulated by the FE method, the result compared with the theoretical solution. It is found that the curves of the normal contact stiffness versus the included angle in the principal curvature direction show similar trends and evolve as a cosine feature. The effects of the parameters on normal contact stiffness are found to show that normal contact stiffness increases and reaches the upper limit gradually with an increase in these parameters.

关键词： contact stiffness joint surface elliptical area asperity

Reduction of friction by normal *** of contact stiffness

在线全文

学校读者我要写书评

暂无评论

Friction 2017年第1期5卷 45-55页

作者： M.POPOV V.L.POPOV N.V.POPOV Berlin University of Technology Berlin 10623 GermanyTomsk Polytechnic University Tomsk 634050 RussiaTomsk State University Tomsk 634050 Russia Berlin University of Technology Berlin 10623 Germany

The present paper is devoted to a theoretical analysis of sliding friction under the influence of oscillations perpendicular to the sliding *** contrast to previous works we analyze the influence of the stiffness of the tribological contact in detail and also consider the case of large oscillation amplitudes at which the contact is lost during a part of the oscillation period,so that the sample starts to 'jump'.It is shown that the macroscopic coefficient of friction is a function of only two dimensionless parameters-a dimensionless sliding velocity and dimensionless oscillation *** function in turn depends on the shape of the contacting *** the present paper,analysis is carried out for two shapes:a flat cylindrical punch and a parabolic *** we consider 'stiff systems',where the contact stiffness is small compared with the stiffness of the *** role of the system stiffness will be studied in more detail in a separate paper.

关键词： sliding friction out-of-plane oscillation contact stiffness coefficient of friction active control of friction

Elastohydrodynamic Lubrication Interface stiffness and Damping Considering Asperity Lateral contact

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2024年第1期37卷 109-123页

作者： Zhiqiang Gao Yu Zhang Xian Wei Yanfang Zhu Lixia Peng Weiping Fu Wen Wang School of Mechanical and Precision Instrument Engineering Xi'an University of TechnologyXi'an 710048China School of Intelligent Manufacturing Panzhihua UniversityPanzhihua 617000China Material Corrosion and Protection Key Laboratory of Sichuan Province Sichuan University of Light Chemical TechnologyYibin 644002China School of Mechanical Engineering Anyang Institute of TechnologyAnyang 455099China

Elastohydrodynamic lubrication(EHL)point contact occurs between two rough surfaces at the mesoscopic level,while the interaction of rough surfaces involves contact between asperities at the microscale *** most cases,the contact between asperities within an interface takes the form of lateral contact rather than peak *** devoid of contact asperities are filled with lubricating ***,conventional models often oversimplify lateral contact forms as interactions between asperities and a smooth,rigid *** simplifications fail to accurately represent the true contact conditions and can lead to inaccuracies in the analysis of EHL’s contact *** address this issue,we have developed a novel EHL interface model comprising two rough *** model allows us to explore the influence of asperity height,contact angle,and contact azimuth angle on EHL interface performance.

关键词： EHL interface Asperity lateral contact contact stiffness Damping

Active Compliance Control of a Position‑Controlled Industrial Robot for Simulating Space Operations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2022年第6期35卷 63-75页

作者： Jun He Mingjin Shen Feng Gao Haibo Zhang State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Beijing Institute of Control Engineering Beijing 100190China

An industrial robot with a six-axis force/torque sensor is usually used to produce a zero-gravity environment for testing space robotic ***,using traditional force control methods,such as admittance control,causes position-controlled industrial robots to undergo from force divergence owing to intrinsic time *** this paper,a new force control method is proposed to eliminate the force divergence.A hardware-in-the-loop(HIL)simulator with an industrial robot is first *** free-floating satellite dynamics and the motion mapping from the satellites to simulator are both ***,the effects of measurement delay and dynamic response delay on contact velocity and force are *** that,a real-time estimation method for contact stiffness and damping is proposed based on the adaptive Kalman *** measurement delay is compensated by a phase lead ***,the identified contact parameters are adopted to modify contact forces,and thus the dynamics response delay can be compensated ***,a co-simulation and experiments were conducted to verify the force control *** results show that contact stiffness and damping could be identified exactly and that the simulation divergence could be *** paper proposes an active compliance control method that can deal with force constrained tasks of a position-controlled robot in unknown environments.

关键词： contact stiffness Parameter estimation Force control Space operation

Evaluating Local Elasticity of the Metal Nano-films Quantitatively Based on Referencing Approach of Atomic Force Acoustic Microscopy

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第6期25卷 1281-1286页

作者： ZHANG Gaimei HE Cunfu WU Bin CHEN Qiang College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology Beijing 100124 China Laboratory of Plasma Physics and Materials Beijing Institute of Graphic Communication Beijing 102600 China

Traditional technique such nanoindenter（NI） can＇t measure the local elastic modulus at nano-scale（lateral）. Atomic force acoustic microscopy （AFAM） is a dynamic method, which can quantitatively determine indentation modulus by measuring the contact resonance spectra for high order modes of the cantilever. But there are few reports on the effect of experimental factors, such length of cantilever, contact stiffness on measured value. For three different samples, including copper（Cu） film with 110 nm thickness, zinc（Zn） film of 90 nm thickness and glass slides, are prepared and tested, using referencing approach in which measurements are performed on the test and reference samples （it＇s elastic modulus is known）, and their contact resonance spectra are measured used the AFAM system experimentally. According to the vibration theory, from the lowest two contact resonance frequencies, the tip-sample contact stiffness is calculated, and then the values for the elastic properties of test sample, such as the indentation modulus, are determined. Using AFAM system, the measured indentation modulus of copper nano-film, zinc nano-film and glass slides are 113.53 GPa, 87.92 GPa and 57.04 GPa, which are agreement with literature values Mcu--105-130 GPa, Mzn = 88.44 GPa and Molass = 50-90 GPa. Furthermore, the sensitivity of contact resonance frequency to contact stiffness is analyzed theoretically. The results show that for the cantilevers with the length 160 pm, 225 μm and 520 μm respectively, when contact stiffness increases from 400 N/m to 600 N/m, the increments of first contact resonance frequency are 126 kHz, 93 kHz and 0.6 kHz, which show that the sensitivity of the contact resonance frequency to the contact stiffness reduces with the length of cantilever increasing. The novel method presented can characterize elastic modulus of near surface for nano-film and bulk material, and local elasticity of near surface can be evaluated by optimizing the experimental parameters using

关键词： local elasticity atomic force acoustic microscope(AFAM) contact stiffness referencing approach

Ionic liquids on uncharged and charged surfaces: In situ microstructures and nanofriction

在线全文

学校读者我要写书评

暂无评论

Friction 2022年第11期10卷 1893-1912页

作者： Rong AN Yudi WEI Xiuhua QIU Zhongyang DAI Muqiu WU Enrico GNECCO Faiz Ullah SHAH Wenling ZHANG Herbert Gleiter Institute of Nanoscience School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China High Performance Computing Department National Supercomputing Center in ShenzhenShenzhen 518055China Otto Schott Institute of Materials Research(OSIM) Friedrich Schiller University JenaJena 07743Germany Chemistry of Interfaces LuleåUniversity of TechnologyLulea 97187Sweden School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China

In situ changes in the nanofriction and microstructures of ionic liquids(ILs)on uncharged and charged surfaces have been investigated using colloid probe atomic force microscopy(AFM)and molecular dynamic(MD)*** representative ILs,[BMIM][BF_(4)](BB)and[BMIM][PF_(6)](BP),containing a common cation,were selected for this *** torsional resonance frequency was captured simultaneously when the nanoscale friction force was measured at a specified normal load;and it was regarded as a measure of the contact stiffness,reflecting in situ changes in the IL microstructures.A higher nanoscale friction force was observed on uncharged mica and highly oriented pyrolytic graphite(HOPG)surfaces when the normal load increased;additionally,a higher torsional resonance frequency was detected,revealing a higher contact stiffness and a more ordered IL *** nanofriction of ILs increased at charged HOPG surfaces as the bias voltage varied from 0 to 8 V or from 0 to−8 *** simultaneously recorded torsional resonance frequency in the ILs increased with the positive or negative bias voltage,implying a stiffer IL layer and possibly more ordered ILs under these *** simulation reveals that the[BMIM]+imidazolium ring lies parallel to the uncharged surfaces preferentially,resulting in a compact and ordered IL *** parallel“sleeping”structure is more pronounced with the surface charging of either sign,indicating more ordered ILs,thereby substantiating the AFM-detected stiffer IL layering on the charged *** in situ observations of the changes in nanofriction and microstructures near the uncharged and charged surfaces may facilitate the development of IL-based applications,such as lubrication and electrochemical energy storage devices,including supercapacitors and batteries.

关键词： microstructure friction contact stiffness charged surfaces ionic liquids(ILs) molecular simulation

Morphology and contact mechanics influence adhesive characteristics of Dung Beetle's bristle and Gecko's setae

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第9期17卷 1074-1081页

作者： Yue David China Institute of Bio-Inspired Structure and Surface Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016

Geckos(Gekko gecko)use their hairy setae to adhere on various solid surfaces and dung beetles(Copris ochus Motschulsky)use their hairy bristles to anti-adhere in sticky *** study why two hairy systems express a conflict in functions by using SEM,histological approaches and functional *** models and various parameters were collected and *** on the morphological data and functional experimental results carried out by natural and denatured gecko setae and beetle bristles,we first demonstrated that the stiffness along the hair is 1000 to 30000 times that perpendicular to the *** stiffness difference is the key factor leading to the two hairy systems’ functional *** of gecko setae reduces contact stiffness,increases contact points and real contact area that results in amazing adhesive *** the other hand,stiff bristles in a beetle have higher contact stiffness,which reduces the real contact area and decreases the adhesion between two contact *** of gecko setae destroys the hierarchical structure,increases the contact stiffness and results in a decrease of adhesion ***,deformation of beetle bristles destroys the erect structure of the hair,interconnects the separated bristles and thus decreases the anti-adhesive *** observations inspire us in designing anti-adhesive and adhesive biomimetic systems

关键词： Adherence Morphology contact stiffness Beetle bristles Gecko setae contact mechanics

Equivalent Kelvin Impact Model for Seismic Pounding Analysis of Bridges

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2006年第B09期12卷 83-87页

作者： DING Yang YUE Fuqing LI Zhongxian School of Civil Engineering Tianjin University Tianjin 300072 China

Based on Hertz contact theory, a method to determine the parameters of Kelvin impact model for seismic pounding analysis of bridges is proposed. The impact stiffness of Kelvin model is determined by the ratio of maximum impact force to maximum contact deformation, which is calculated based on Hertz contact theory with considering the vibration effect. The restitution coefficient which has great influence on the damping coefficient of Kelvin impact model is investigated by numerical analysis. Numerical results indicate that the impact stiffness of Kelvin impact model increases with the increment of the Hertz contact stiffness, approaching velocity or the length ratio of short to long girders. Vibration effect has remarkable influence on the impact stiffness and cannot be neglected. The restitution coefficient decreases when approaching velocity increases or the length ratio of short girder to long girder decreasing. The practical ranges of impact stiffness and restitution coefficient are obtained as 3 × 10^8--6 × 10^8 N/m and 0.6-3.95 respectively.

关键词： bridge seismic pounding impact model contact stiffness restitution coefficient

Stability analysis of the rotating tribological pair system on circular-disc end faces

在线全文

学校读者我要写书评

暂无评论

Journal of Southeast University(English Edition) 2020年第1期36卷 24-31页

作者： Chen Long Zhang Jianrun School of Mechanical Engineering Southeast University Nanjing 211189 China

In order to study the stability of friction and contact of the rotating tribological pair system,considering the influence of the changeable factors on the stability,the system dynamics analysis model based on the Lagrange equation is firstly *** surface contact stiffness model is determined on the basis of the fractal *** model of the friction torque with velocities is created by using the Stribeck friction *** Lyapunov indirect method is employed to explore the eigenvalue problem of the system state *** effects of the applied load,the fractal dimension,the fractal scaling coefficient and the Stribeck coefficient on the system stability are investigated in *** numerical simulation results demonstrate that the tribological pair system is prone to causing system instability at low speed,and the system instability boundary value decreases when the Stribeck coefficient *** fractal dimension and the fractal scaling coefficient impact the system stability slightly when fractal dimensions are large,and the system instability can be reduced by properly increasing the surface ***,the system instability evidently increases with the increase in the applied load and the Stribeck *** achievements can provide a reference and theoretical support for the analysis of the dynamic performance of the tribological pair system.

关键词： rotating tribological pair system contact stiffness Stribeck effect dynamic model stability