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Interactive mechanism and friction modelling of transient tribological phenomena in metal forming processes: A review
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作者 Xiao YANG Heli LIU +4 位作者 Lemeng ZHANG Yiran HU Denis J.POLITIS Mohammad M.GHARBI Liliang WANG 《Friction》 SCIE EI CAS CSCD 2024年第3期375-395,共21页
The accurate representation of tribological boundary conditions at the tool–workpiece interface is crucial for analysis and optimization of formability,material flow,and surface quality of components during metal for... The accurate representation of tribological boundary conditions at the tool–workpiece interface is crucial for analysis and optimization of formability,material flow,and surface quality of components during metal forming processes.It has been found that these tribological conditions vary spatially and historically with process parameters and contact conditions.These time-dependent tribological behaviours are also known as transient tribological phenomena,which are widely observed during forming processes and many other manufacturing application scenarios.However,constant friction values are usually assigned to represent complex and dynamic interfacial conditions,which would introduce deviations in the relevant predictions.In this paper,transient tribological phenomena and the contemporary understanding of the interaction between friction and wear are reviewed,and it has been found that these phenomena are induced by the transitions of friction mechanisms and highly dependent on complex loading conditions at the interface.Friction modelling techniques for transient behaviours for metal forming applications are also reviewed.To accurately describe the evolutionary friction values and corresponding wear during forming,the advanced interactive friction modelling has been established for different application scenarios,including lubricated condition,dry sliding condition(metal-on-metal contact),and coated system. 展开更多
关键词 transient tribological phenomena interactive friction mechanism modelling techniques metal forming
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Effect of infiltrating Si on friction properties of C/C composites 被引量:1
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作者 马运柱 黄伯云 +4 位作者 熊翔 肖鹏 李江鸿 黄启忠 易茂忠 《Journal of Central South University of Technology》 2003年第3期173-176,共4页
In order to improve the friction-wear properties of the C/C composites for aircraft brake pairs, the fric-tion behavior of samples with infiltrating Si was investigated. The influence of Si smearing thickness on frict... In order to improve the friction-wear properties of the C/C composites for aircraft brake pairs, the fric-tion behavior of samples with infiltrating Si was investigated. The influence of Si smearing thickness on frictionproperties was studied in detail. The results show that with the increase of Si smearing thickness and β-SiC content,the friction coefficient reduces from 0.40 to 0.30; the linear wear of stators increases from 2.0 μm to 18.9 μm percycle, and that of rotors increases from 1.4 μm to 22.6 μm per cycle; mass wear of stators increases from 20.6 mgto 126.9 mg per cycle, and that of rotors increases from 13.7 mg to 166.2 mg per cycle. On the other hand, whena large number of inhomogeneous β-SiC particulates are performed, friction surfaces of the samples flake off layer bylayer and many nicks are observed. 展开更多
关键词 C/C composites infiltrating Si modifying property friction mechanism
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Constitutive Model of Friction Stir Weld with Consideration of its Inhomogeneous Mechanical Properties 被引量:3
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作者 ZHANG Ling MIN Junying +3 位作者 WANG Bin LIN Jianping LI Fangfang LIU Jing 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第2期357-364,共8页
In practical engineering, finite element(FE) modeling for weld seam is commonly simplified by neglecting its inhomogeneous mechanical properties. This will cause a significant loss in accuracy of FE forming analysis... In practical engineering, finite element(FE) modeling for weld seam is commonly simplified by neglecting its inhomogeneous mechanical properties. This will cause a significant loss in accuracy of FE forming analysis, in particular, for friction stir welded(FSW) blanks due to the large width and good formability of its weld seam. The inhomogeneous mechanical properties across weld seam need to be well characterized for an accurate FE analysis. Based on a similar AA5182 FSW blank, the metallographic observation and micro-Vickers hardness analysis upon the weld cross-section are performed to identify the interfaces of different sub-zones, i.e., heat affected zone(HAZ), thermal-mechanically affected zone(TMAZ) and weld nugget(WN). Based on the rule of mixture and hardness distribution, a constitutive model is established for each sub-zone to characterize the inhomogeneous mechanical properties across the weld seam. Uniaxial tensile tests of the AA5182 FSW blank are performed with the aid of digital image correlation(DIC) techniques. Experimental local stress-strain curves are obtained for different weld sub-zones. The experimental results show good agreement with those derived from the constitutive models, which demonstrates the feasibility and accuracy of these models. The proposed research gives an accurate characterization of inhomogeneous mechanical properties across the weld seam produced by FSW, which provides solutions for improving the FE simulation accuracy of FSW sheet forming. 展开更多
关键词 constitutive model inhomogeneous mechanical property friction stir welding tailor welded blanks
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Effects of different friction stir welding conditions on the microstructure and mechanical properties of copper plates 被引量:1
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作者 Ali Alavi Nia Ali Shirazi 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2016年第7期799-809,共11页
Friction stir welding is a new and innovative welding method used to fuse materials. In this welding method, the heat generated by friction and plastic flow causes significant changes in the microstructure of the mate... Friction stir welding is a new and innovative welding method used to fuse materials. In this welding method, the heat generated by friction and plastic flow causes significant changes in the microstructure of the material, which leads to local changes in the mechanical properties of the weld. In this study, the effects of various welding parameters such as the rotational and traverse speeds of the tool on the microstructural and mechanical properties of copper plates were investigated; additionally, Charpy tests were performed on copper plates for the first time. Also, the effect of the number of welding passes on the aforementioned properties has not been investigated in previous studies. The results indicated that better welds with superior properties are produced when less heat is transferred to the workpiece during the welding process. It was also found that although the properties of the stir zone improved with an increasing number of weld passes, the properties of its weakest zone, the heat-affected zone, deteriorated. 展开更多
关键词 copper friction stir welding mechanical properties microstructure
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Dry friction and wear properties of intermetallics MoSi_2
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作者 张厚安 刘心宇 +1 位作者 陈平 唐果宁 《中国有色金属学会会刊:英文版》 CSCD 2001年第6期916-919,共4页
The dry friction and wear properties of intermetallics MoSi 2 against 45 steel under different loads were investigated with M 2 type friction and wear tester. Scanning electric microscope (SEM) equipment with micropro... The dry friction and wear properties of intermetallics MoSi 2 against 45 steel under different loads were investigated with M 2 type friction and wear tester. Scanning electric microscope (SEM) equipment with microprobe was employed to analyze the morphology of the friction surface. Results show that the dry friction and wear properties are deeply affected by load. The wear rate of MoSi 2 at the load of 80?N is the maximum which is 36.1?μg/m. On the condition of the load of 150?N, MoSi 2 material has the better friction and wear properties: friction coefficient is 0.28 and wear rate is 10.6?μg/m. With the load increasing, the main friction mechanisms change from microslip and plastic deformation to adhesive effect, and the main wear mechanisms change from plough groove wear and oxidation fatigue wear to adhesive wear. 展开更多
关键词 molybdenum disilicide friction and wear mechanism dry friction
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Friction reactions induced by selective hydrogenation of textured surface under lubricant conditions
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作者 Naizhou DU Xubing WEI +9 位作者 Xiaowei LI Zan CHEN Shiqi LU Jiaqing DING Cunao FENG Kai CHEN Jianghao QIAO Dekun ZHANG Kwang-Ryeol LEE Tiancai ZHANG 《Friction》 SCIE EI CAS CSCD 2024年第1期174-184,共11页
The passivation of hydrogen atoms and the conformation of textured surfaces under oil-lubricated conditions are effective strategies to obtain amorphous carbon(a-C)films with extremely low friction.It is critical to u... The passivation of hydrogen atoms and the conformation of textured surfaces under oil-lubricated conditions are effective strategies to obtain amorphous carbon(a-C)films with extremely low friction.It is critical to understanding the influence mechanism of selective surface hydrogenation on the tribological behaviors of textured a-C film under oil-lubricated conditions.In particular,the interactions of hydrogen atoms and lubricants are confusing,which is enslaved to the in situ characterization technique.The reactive molecular dynamics(RMD)simulations were conducted to analyze the friction response of textured a-C films with selective hydrogenation surfaces under oil-lubricated conditions.The results indicate that the existence of hydrogen atoms on specific bump sites significantly decreases the friction coefficient(μ)of textured a-C film,which is highly dependent on the surface hydrogen content.The repulsion between hydrogen atoms and lubricant molecules prompts the formation of a dense lubricant film on the surface of the mating material.Interestingly,with the enhancement of the surface hydrogen content,the passivation of the friction interface and the repulsion between hydrogen atoms and lubricants play dominant roles in reducing the friction coefficient instead of hydrodynamic lubrication. 展开更多
关键词 textured amorphous carbon(a-C) selective hydrogenation oil lubrication friction mechanism reactive molecular dynamics(RMD)
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Sliding modes of fault activation under constant normal stiffness conditions 被引量:2
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作者 Chuanqing Zhang Jie Xu +3 位作者 Shengji Jin Guojian Cui Yuhang Guo Lingyu Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第5期1213-1225,共13页
Fault activation has been the focus of research community for years.However,the studies of fault activation remain immature,such as the fault activation mode and its major factors under constant normal stiffness(CNS)c... Fault activation has been the focus of research community for years.However,the studies of fault activation remain immature,such as the fault activation mode and its major factors under constant normal stiffness(CNS)conditions associated with large thickness of fault surrounding rock mass.In this study,the rock friction experiments were conducted to understand the fault activation modes under the CNS conditions.Two major parameters,i.e.the initial normal stress and loading rate,were considered and calibrated in the tests.To reveal the response mechanism of fault activation,the local strains near the fault plane were recorded,and the macroscopic stresses and displacements were analyzed.The testing results show that the effect of displacement-controlled loading rate is more pronounced under the CNS conditions than that under constant normal load(CNL)conditions.Both the normal and shear stresses drop suddenly when the stick-slip occurs.The decrease and increase of the normal stress are synchronous with the shear stress in the regular stick-slip scenario,but mismatch with the shear stress during the chaotic stick-slip process.The results are helpful for understanding the fault sliding mode and the prediction and prevention of fault slip. 展开更多
关键词 Fault activation Rock friction mechanics Sliding modes Constant normal stiffness(CNS) Displacement-controlled loading rates ROCKBURST
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Tribological Behavior of Plant Oil-Based Extreme Pressure Lubricant Additive in Water-Ethylene Glycol Liquid 被引量:1
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作者 Haiyang Ding Xiaohua Yang +4 位作者 Lina Xu Mei Li Shouhai Li Jianling Xia 《Journal of Renewable Materials》 SCIE 2019年第12期1391-1401,共11页
A water-soluble lubricant additive(RSOPE)was prepared by esterification reaction using fatty acid from rubber seed oil.The RSOPE was added into water-ethylene glycol(W-EG)solution as lubricant additive.Dispersion stab... A water-soluble lubricant additive(RSOPE)was prepared by esterification reaction using fatty acid from rubber seed oil.The RSOPE was added into water-ethylene glycol(W-EG)solution as lubricant additive.Dispersion stability and rheological properties were investigated.We used a four-ball tribotester to assess the lubrication performance of W-EG based fluid with the RSOPE additive.The stainless-steel surface was analyzed using scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).Good dispersion stability was observed in the RSOPE/W-EG solutions.Furthermore,non-Newtonian fluid behavior at low shear rates and Newtonian fluid behavior at high shear rates was exhibited.The addition of RSOPE into water-glycol reduced the friction coefficients(COF)and wear scar diameters(WSD).The maximum non-seizure loads(PB)increased from 98 N to 752 N and the W-EG solution with RSOPE had good corrosion resistance properties.Good tribological performances for W-EG solution with RSOPE were attributed to the boundary tribofilm composed of iron oxide,iron phosphide and so on. 展开更多
关键词 Rubber seed oil fatty acid water-soluble additive tribological performance friction mechanism
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A review of down-hole tubular string buckling in well engineering 被引量:14
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作者 De-Li Gao Wen-Jun Huang 《Petroleum Science》 SCIE CAS CSCD 2015年第3期443-457,共15页
Down-hole tubular string buckling is the most classic and complex part of tubular string mechanics in well engineering. Studies of down-hole tubular string buckling not only have theoretical significance in revealing ... Down-hole tubular string buckling is the most classic and complex part of tubular string mechanics in well engineering. Studies of down-hole tubular string buckling not only have theoretical significance in revealing the buckling mechanism but also have prominent practical value in design and control of tubular strings. In this review, the basic principles and applicable scope of three classic research methods (the beam-column model, buck- ling differential equation, and energy method) are intro- duced. The critical buckling loads and the post-buckling behavior under different buckling modes in vertical, inclined, horizontal, and curved wellbores from different researchers are presented and compared. The current understanding of the effects of torque, boundary condi- tions, friction force, and connectors on down-hole tubular string buckling is illustrated. Meanwhile, some unsolved problems and controversial conclusions are discussed. Future research should be focused on sophisticated description of buckling behavior and the coupling effect of multiple factors. In addition, active control of down-hole tubular string buckling behavior needs some attention urgently. 展开更多
关键词 Down-hole tubular mechanics Tubular stringbuckling Wellbore configuration Boundary condition friction force
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Effect of mechanical degradation of laminated elastomeric bearings and shear keys upon seismic behaviors of small-to-medium-span highway bridges in transverse direction 被引量:2
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作者 Wu Gang Wang Kehai +1 位作者 Zhang Panpan Lu Guanya 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第1期205-220,共16页
Laminated elastomeric bearings have been widely used for small-to-medium-span highway bridges in China, in which concrete shear keys are set transversely to prohibit large girder displacement. To evaluate bridge seism... Laminated elastomeric bearings have been widely used for small-to-medium-span highway bridges in China, in which concrete shear keys are set transversely to prohibit large girder displacement. To evaluate bridge seismic responses more accurately, proper analytical models of bearings and shear keys should be developed. Based on a series of cyclic loading experiments and analyses, rational analytical models of laminated elastomeric bearings and shear keys, which can consider mechanical degradation, were developed. The effect of the mechanical degradation was investigated by examining the seismic response of a small-to-medium-span bridge in the transverse direction under a wide range of peak ground accelerations(PGA). The damage mechanism for small-to-medium-span highway bridges was determined, which can explain the seismic damage investigation during earthquakes in recent years. The experimental results show that the mechanical properties of laminated elastomeric bearings will degrade due to friction sliding, but the degree of decrease is dependent upon the influencing parameters. It can be concluded that the mechanical degradation of laminated elastomeric bearings and shear keys play an important role in the seismic response of bridges. The degradation of mechanical properties of laminated elastomeric bearings and shear keys should be included to evaluate more precise bridge seismic performance. 展开更多
关键词 bridge engineering mechanical degradation seismic response friction sliding shear keys
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Local melting mechanism and its effects on mechanical properties of friction spot welded joint for Al-Zn-Mg-Cu alloy 被引量:5
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作者 Yunqiang Zhao Chungui Wang +2 位作者 Jizhong Li Jinhong Tan Chunlin Dong 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第1期185-191,共7页
Local melting and the eutectic film and liquation crack formation mechanisms during friction spot weld- ing (FSpW) of Al-Zn-Mg-Cu alloy were studied by both experiment and finite element simulation. Their effects on... Local melting and the eutectic film and liquation crack formation mechanisms during friction spot weld- ing (FSpW) of Al-Zn-Mg-Cu alloy were studied by both experiment and finite element simulation. Their effects on mechanical properties of the joint were examined. When the welding heat input was high, the peak temperature in the stir zone was higher than the incipient melting temperature of the Al-Zn-Mg-Cu alloy. This resulted in local melting along the grain boundaries in this zone. In the retreating stage of the welding process, the formed liquid phase was driven by the flowing plastic material and redistributed as a "U-shaped" line in the stir zone. In the following cooling stage, this liquid phase transformed into eutectic films and liquation cracks. As a result, a new characteristic of"U" line that consisted of eutectic films and liquation cracks is formed in the FSpWjoin. This "U" line was located in the high stress region when the FSpW joint was loaded, thus it was adverse to the mechanical properties of the FSpW joint. During tensile shear tests, the "U" line became a preferred crack propagation path, resulting in the occurrence of brittle fracture. 展开更多
关键词 friction spot welding Numerical simulation Local melting Liquation crack Mechanical property
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Hierarchical self-assembled structure and frictional response of phthalocyanine molecules 被引量:1
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作者 Yijun QIAO Jian SONG +3 位作者 Hongyu SHI Hongdong WANG Shizhu WEN Yuhong LIU 《Friction》 SCIE EI CAS CSCD 2023年第3期354-368,共15页
Solid evidence is needed to demonstrate the effect of molecular orientation and structure on the frictional property of boundary lubricants.In this work,the frictional properties of phthalocyanine self-assembled monol... Solid evidence is needed to demonstrate the effect of molecular orientation and structure on the frictional property of boundary lubricants.In this work,the frictional properties of phthalocyanine self-assembled monolayers(SAMs)with face-on(aromatic cores parallel to the substrate)and edge-on(aromatic cores stand on the substrate)orientations have been compared and the in situ structural variation of edge-on SAMs under frictional shear has been revealed by atomic force microscope(AFM).Face-on oriented SAMs show lower adhesion,lower friction,and stronger wear resistance,compared with edge-on oriented SAMs.Hierarchical structures of edge-on oriented SAMs have been revealed by frictional topography,which are consisted of nanoscale columns,micron-scale stripes,and centimeter-scale monolayer.The column structure deforms under increasing load force,leading to a stepwise friction force curve and a transition among three friction states(ordered friction,collapsed friction,and worn friction).The structural deformation depends on both the order degree and anisotropic stiffness of columns.Columns in phthalocyanine SAMs show a larger stiffness when shearing against molecular plane than shearing along the molecular plane.The presented study on the interfacial structure and frictional mechanism promisingly supports the designing of novel boundary lubricants and their application in engineering. 展开更多
关键词 hierarchical assembly molecular orientation frictional mechanism PHTHALOCYANINE
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Study on Tribology Performance of Different Lubricant Additives under Atmospheric Pressure and High Vacuum Conditions
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作者 Peng Qian Huang Zhiyang +2 位作者 Yang He Song Haiqing Zhang Jianrong 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2016年第4期81-91,共11页
By using PAO-10 as the base oil, the tribological behavior of 11 additives under high vacuum condition was evaluated. By adopting some surface analytical instruments, such as scanning electron microscopy(SEM), energy ... By using PAO-10 as the base oil, the tribological behavior of 11 additives under high vacuum condition was evaluated. By adopting some surface analytical instruments, such as scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS), the tribological mechanisms of these additives were studied. In air, O_2 can react with metal to form metal oxide that can protect the surfaces of rubbing pair during the tribological tests. According to the theory of the competitive adsorption, the function of some active elements is weakened. In a vacuum environment, the additives contributed more to the lubrication performance. The sulfur-containing additives could react with Fe to produce Fe Sx and "M—C" bonds("M" represents metal). They both had contributions to the lubrication. As for the phosphorus-containing additives, they only generated the phosphates during the tests. When the sulfur and phosphorus-containing additives were applied, the generated phosphates and Fe Sx had the primary contribution to the lubrication performance during the tests. 展开更多
关键词 anti-wear additive high vacuum lubrication mechanism anti-wear properties friction reducing properties
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Homogenization with the Quasistatic Tresca Friction Law:Qualitative and Quantitative Results
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作者 Changqing YE Eric T.CHUNG Jun-zhi CUI 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2023年第5期781-802,共22页
Modeling of frictional contacts is crucial for investigating mechanical performances of composite materials under varying service environments.The paper considers a linear elasticity system with strongly heterogeneous... Modeling of frictional contacts is crucial for investigating mechanical performances of composite materials under varying service environments.The paper considers a linear elasticity system with strongly heterogeneous coefficients and quasistatic Tresca friction law,and studies the homogenization theories under the frameworks of H-convergence and small ε-periodicity.The qualitative result is based on H-convergence,which shows the original oscillating solutions will converge weakly to the homogenized solution,while the author’s quantitative result provides an estimate of asymptotic errors in H^(1)-norm for the periodic homogenization.This paper also designs several numerical experiments to validate the convergence rates in the quantitative analysis. 展开更多
关键词 HOMOGENIZATION frictional contact mechanics Quasistatic Tresca frictionlaw
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Microstructural formation and mechanical performance of friction stir double-riveting welded Al-Cu joints
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作者 Shude JI Zhiqing ZHANG +3 位作者 Peng GONG Hua LIU Xiao CUI Yewei ZHANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第8期454-471,共18页
A novel friction stir double-riveting welding(FSDRW) technology was proposed in order to realize the high-quality joining of upper aluminum(Al) and lower copper(Cu) plates,and this technology employed a Cu column as a... A novel friction stir double-riveting welding(FSDRW) technology was proposed in order to realize the high-quality joining of upper aluminum(Al) and lower copper(Cu) plates,and this technology employed a Cu column as a rivet and a specially designed welding tool with a large concave-angle shoulder. The formations, interfacial characteristics, mechanical properties and fracture features of Al/Cu FSDRW joints under different rotational velocities and dwell times were investigated. The results showed that the well-formed FSDRW joint was successfully obtained.The cylindrical Cu column was transformed into a double riveting heads structure with a Cu anchor at the top and an Al anchor at the bottom, thereby providing an excellent mechanical interlocking.The defect-free Cu/Cu interface was formed at the lap interface due to the sufficient metallurgical bonding between the Cu column and the Cu plate, thereby effectively inhibiting the propagation of crack from the intermetallic compound layer at the lap interface between the Al and Cu plates. The tensile shear load of joint was increased first and then decreased when the rotational velocity and dwell time of welding tool increased, and the maximum value was 5.52 k N. The FSDRW joint presented a mixed mode of ductile and brittle fractures. 展开更多
关键词 Dissimilar Al/Cu metals friction stir double-riveting welding Mechanical interlocking Mechanical properties Metallurgical bonding
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Tribological behavior of lubricant-impregnated porous polyimide
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作者 Jinbang LI Ningning ZHOU Janet S.S.WONG 《Friction》 SCIE EI CAS CSCD 2024年第4期711-725,共15页
Porous materials impregnated with lubricants can be used in conditions where limited lubricant is desirable.In this work,three porous polyimides(PPI)with different densities were prepared.Polyalphaolefin(PAO)impregnat... Porous materials impregnated with lubricants can be used in conditions where limited lubricant is desirable.In this work,three porous polyimides(PPI)with different densities were prepared.Polyalphaolefin(PAO)impregnated PPI(iPPI)discs were rubbed against steel and sapphire balls.In operando observations of the iPPI-sapphire contacts show that oil is released under an applied load,forming a meniscus around contacts.Cavitation at the outlet is created at high sliding speeds.The amount of released oil increases with increasing PPI porosity.Contact moduli,E*,estimated based on the actual contact size show that trapped oil in iPPIs contributes to load support.At higher speeds,tribological rehydration of the contact occurs in low density iPPI,with that E*rises with speed.For high density PPIs,high speeds give a constantly high E*which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil exudation.Friction of iPPI-steel contacts is governed by the mechanical properties of the PPI,the flow of the lubricant,and the roughness of the PPI surfaces.For low-and medium-density(highly porous,high roughness)PPIs,large amount of oil is released,and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological rehydration.For high density(low porosity)PPI,with lower roughness,hydrodynamic lubrication is achieved which gives the lowest friction.Our results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness,stiffness,oil flow,and oil retentions. 展开更多
关键词 POLYIMIDE porous material friction mechanism polymer limited lubrication
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Nanoscopic tribological characteristics of a cryogenically cycled Zr-based metallic glass
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作者 Qian Jia Qiaosheng Xia +5 位作者 Qing Zhou Yucheng Wang Yue Ren Yu Meng Haifeng Wang Feng Zhou 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2024年第6期113-126,共14页
Optimized macroscopic tribological behavior can be anticipated in metallic glasses(MGs)by cryogenic cycling treatment(CCT),which is attributed to enhanced plasticity.However,the intrinsic friction mechanisms of MGs in... Optimized macroscopic tribological behavior can be anticipated in metallic glasses(MGs)by cryogenic cycling treatment(CCT),which is attributed to enhanced plasticity.However,the intrinsic friction mechanisms of MGs induced by cryogenic rejuvenation are still poorly understood.In the present study,nanoscopic wear tests were conducted on the Zr-based MGs surface with different CCT cycles using atomic force microscopy(AFM).After CCT treatment with 100 cycles,the MG displays the highest adhesion and ploughing frictions,but significantly improved anti-wear properties.Adhesion tests and molecular dynamics simulations disclose that the increased adhesion is attributed to the dominance of liquid-like regions in the CCT-treated MGs,and the impact of reduced hardness and weak elastic recovery results in the deteriorated ploughing friction.The enhanced plasticity effectively dissipates the strain from the AFM tip through multiple shear bands and weakens the adhesion during deformation,giving rise to excellent wear resistance.This study elucidates the promoting effect of CCT on the outstanding antiwear performance of MGs,and is helpful for the development of novel alloys. 展开更多
关键词 metallic glasses cryogenic cycling treatment nanoscope wear friction mechanism
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Influence of a carbon-based tribofilm induced by the friction temperature on the tribological properties of impregnated graphite sliding against a cemented carbide 被引量:6
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作者 Jun ZHAO Qingzhan LI +5 位作者 Shuangxi LI Shicong LI Guangyan CHEN Xinghua LIU Yongyong HE Jianbin LUO 《Friction》 SCIE EI CAS CSCD 2021年第4期686-696,共11页
Impregnated graphite has attracted considerable attention and has been widely used as an ideal friction material in many fields.However,the influence of the friction temperature on its tribological properties has not ... Impregnated graphite has attracted considerable attention and has been widely used as an ideal friction material in many fields.However,the influence of the friction temperature on its tribological properties has not been clearly studied;furthermore,the evolution mechanism of transferred tribofilm is unknown.In this study,the tribological properties of impregnated graphite were investigated at different friction temperatures,and the evolution of the carbon-based tribofilm was also determined.The results revealed that the tribological properties significantly improved with an increase in friction temperature.The friction coefficient and wear depth of impregnated graphite reduced by 68%and 75%,respectively,at a high temperature of 160℃ compared with those of non-impregnated graphite.The significant properties of the impregnated graphite can be attributed to a transferred carbon-based tribofilm with an ordered structure induced by the friction temperature,which uniformly and stably adsorbs on friction interfaces.This study provides an important basis for designing graphite-based friction materials with improved properties suited for industrial applications. 展开更多
关键词 impregnated graphite tribological properties TRIBOFILM friction mechanism
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Role of titanium carbide and alumina on the friction increment for Cu-based metallic brake pads under different initial braking speeds 被引量:1
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作者 Tao PENG Qingzhi YAN +1 位作者 Xiaolu ZHANG Yan ZHUANG 《Friction》 SCIE EI CAS CSCD 2021年第6期1543-1557,共15页
To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds,pad materials with two typical abrasives,titanium carbide(TiC)and alumina(Al_(2)O_(3)),were produce... To understand the effect of abrasives on increasing friction in Cu-based metallic pads under different braking speeds,pad materials with two typical abrasives,titanium carbide(TiC)and alumina(Al_(2)O_(3)),were produced and tested using a scale dynamometer under various initial braking speeds(IBS).The results showed that at IBS lower than 250 km/h,both TiC and Al_(2)O_(3) particles acted as hard points and exhibited similar friction-increasing behavior,where the increase in friction was not only enhanced as IBS increased,but also enhanced by increasing the volume fraction of the abrasives.However,at higher IBS,the friction increase was limited by the bonding behavior between the matrix and abrasives.Under these conditions,the composite containing TiC showed a better friction-increasing effect and wear resistance than the composite containing Al_(2)O_(3) because of its superior particle-matrix bonding and coefficient of thermal expansion(CTE)compatibility.Because of the poor interface bonding between the matrix and Al_(2)O_(3),a transition phenomenon exists in the Al_(2)O_(3)-reinforced composite,in which the friction-increasing effect diminished when IBS exceeded a certain value. 展开更多
关键词 high-speed train friction mechanisms brake pads ABRASIVES
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Theory and contents of frictional mechanics 被引量:4
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作者 Ping HUANG Qianqian YANG 《Friction》 SCIE EI CAS 2014年第1期27-39,共13页
In this paper,we first discuss the development of the field of tribology,and highlight some of the main problems encountered in this area,such as lack of systematicness,loose correlation,and inadequate focus on the mi... In this paper,we first discuss the development of the field of tribology,and highlight some of the main problems encountered in this area,such as lack of systematicness,loose correlation,and inadequate focus on the microscopic perspective.Then,we provide basic formulas of frictional mechanics while considering the friction effect on classical mechanics formulae.In order to carry out the frictional mechanics analysis,we first classify the interface.According to the size analysis of surface films,the manufacturing roughness of the surface,the contact width,and the roller radius of the rolling contact bearing,frictional mechanics has the features of interface mechanics,while interfaces are classified based on the presence or absence of a medium.Based on the classification,we further analyze the pressure and frictional stress of sliding and rolling friction problems without a medium,such as a slider,wedge key,and V belt.We also analyze problems with a medium,such as journal and rolling contact bearings.By comparing these results with those of classical mechanics without considering friction,we see that(1)friction causes deviations in the result for classical mechanics which does not consider friction,and(2)if the frictional stress and normal pressure affect each other,their interaction should be considered simultaneously.Finally,we summarize the friction problems,namely,sliding and rolling,with and without a medium,and deformed and non-deformed.From our analysis,we propose two conclusions.First,the frictional mechanics problem is a deviation of the classical mechanics problem,and secondly,frictional stress and normal pressure influence each other. 展开更多
关键词 frictional mechanics INTERFACE normal pressure frictional stress
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