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Theoretical Modeling and Surface Roughness Prediction of Microtextured Surfaces in Ultrasonic Vibration-Assisted Milling
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作者 Chenbing Ni Junjie Zhu +3 位作者 Youqiang Wang Dejian Liu Xuezhao Wang Lida Zhu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第2期163-183,共21页
Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions,such as reducing friction,improving wear and increasing wettability.Accurate prediction of micro/nano surface te... Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions,such as reducing friction,improving wear and increasing wettability.Accurate prediction of micro/nano surface textures is of great significance for the design,fabrication and application of functional textured surfaces.In this paper,based on the kinematic analysis of cutter teeth,the discretization of ultrasonic machining process,transformation method of coordinate systems and the cubic spline data interpolation,an integrated theoretical model was established to characterize the distribution and geometric features of micro textures on the surfaces machined by different types of ultrasonic vibration-assisted milling(UVAM).Based on the theoretical model,the effect of key process parameters(vibration directions,vibration dimensions,cutting parameters and vibration parameters)on tool trajectories and microtextured surface morphology in UVAM is investigated.Besides,the effect of phase difference on the elliptical shape in 2D/3D ultrasonic elliptical vibration-assisted milling(UEVAM)was analyzed.Compared to conventional numerical models,the method of the cubic spline data interpolation is applied to the simulation of microtextured surface morphology in UVAM,which is more suitable for characterizing the morphological features of microtextured surfaces than traditional methods due to the presence of numerous micro textures.The prediction of surface roughness indicates that the magnitude of ultrasonic amplitude in z-direction should be strictly limited in 1D rotary UVAM,2D and 3D UEVAM due to the unfavorable effect of axial ultrasonic vibration on the surface quality.This study can provide theoretical guidance for the design and fabrication of microtextured surfaces in UVAM. 展开更多
关键词 Theoretical modeling Microtextured surface Ultrasonic vibration-assisted milling Cubic spline interpolation surface roughness
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Mechanical properties and fracture surface roughness of thermally damaged granite under dynamic splitting
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作者 Yijin Qian Peng Jia +1 位作者 Songze Mao Jialiang Lu 《Deep Underground Science and Engineering》 2024年第1期103-116,共14页
In order to understand the mechanical properties and the fracture surface roughness characteristics of thermally damaged granite under dynamic splitting,dynamic Brazilian splitting tests were conducted on granite samp... In order to understand the mechanical properties and the fracture surface roughness characteristics of thermally damaged granite under dynamic splitting,dynamic Brazilian splitting tests were conducted on granite samples after thermal treatment at 25,200,400,and 600℃.Results show that the dynamic peak splitting strength of thermally damaged granite samples increases with increasing strain rate,showing obvious strain‐rate sensitivity.With increasing temperature,thermally induced cracks in granite transform from intergranular cracks to intragranular cracks,and to a transgranular crack network.Thermally induced damages reduce the dynamic peak splitting strength and the maximum absorbed energy while increasing the peak radial strain.The fracture mode of the thermally damaged granite under dynamic loads is mode Ⅱ splitting failure.By using the axial roughness index Z2 a,the distribution ranges of the wedge‐shaped failure zones and the tensile failure zones in the fracture surfaces under dynamic Brazilian splitting can be effectively identified.The radial roughness index Z_(2)^(r)is sensitive to the strain rate and temperature.It shows a linear correlation with the peak splitting strength and the maximum absorbed energy and a linear negative correlation with the peak radial strain.Z_(2)^(r)can be used to quantitatively estimate the dynamic parameters based on the models proposed. 展开更多
关键词 dynamic splitting fracture surface roughness GraNITE strain rate thermal treatment
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Influence of Surface Ice Roughness on the Aerodynamic Performance of Wind Turbines
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作者 Xin Guan Mingyang Li +2 位作者 Shiwei Wu Yuqi Xie Yongpeng Sun 《Fluid Dynamics & Materials Processing》 EI 2024年第9期2029-2043,共15页
The focus of this research was on the equivalent particle roughness height correction required to account for the presence of ice when determining the performances of wind turbines.In particular,two icing processes(fr... The focus of this research was on the equivalent particle roughness height correction required to account for the presence of ice when determining the performances of wind turbines.In particular,two icing processes(frost ice and clear ice)were examined by combining the FENSAP-ICE and FLUENT analysis tools.The ice type on the blade surfaces was predicted by using a multi-time step method.Accordingly,the influence of variations in icing shape and ice surface roughness on the aerodynamic performance of blades during frost ice formation or clear ice formation was investigated.The results indicate that differences in blade surface roughness and heat flux lead to disparities in both ice formation rate and shape between frost ice and clear ice.Clear ice has a greater impact on aerodynamics compared to frost ice,while frost ice is significantly influenced by the roughness of its icy surface. 展开更多
关键词 Wind turbine icing blade surface roughness aerodynamic characteristics AIRFOIL
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High-order Bragg forward scattering and frequency shift of low-frequency underwater acoustic field by moving rough sea surface
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作者 莫亚枭 张朝金 +2 位作者 鹿力成 孙启航 马力 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期459-470,共12页
Acoustic scattering modulation caused by an undulating sea surface on the space-time dimension seriously affects underwater detection and target recognition.Herein,underwater acoustic scattering modulation from a movi... Acoustic scattering modulation caused by an undulating sea surface on the space-time dimension seriously affects underwater detection and target recognition.Herein,underwater acoustic scattering modulation from a moving rough sea surface is studied based on integral equation and parabolic equation.And with the principles of grating and constructive interference,the mechanism of this acoustic scattering modulation is explained.The periodicity of the interference of moving rough sea surface will lead to the interference of the scattering field at a series of discrete angles,which will form comb-like and frequency-shift characteristics on the intensity and the frequency spectrum of the acoustic scattering field,respectively,which is a high-order Bragg scattering phenomenon.Unlike the conventional Doppler effect,the frequency shifts of the Bragg scattering phenomenon are multiples of the undulating sea surface frequency and are independent of the incident sound wave frequency.Therefore,even if a low-frequency underwater acoustic field is incident,it will produce obvious frequency shifts.Moreover,under the action of ideal sinusoidal waves,swells,fully grown wind waves,unsteady wind waves,or mixed waves,different moving rough sea surfaces create different acoustic scattering processes and possess different frequency shift characteristics.For the swell wave,which tends to be a single harmonic wave,the moving rough sea surface produces more obvious high-order scattering and frequency shifts.The same phenomena are observed on the sea surface under fully grown wind waves,however,the frequency shift slightly offsets the multiple peak frequencies of the wind wave spectrum.Comparing with the swell and fully-grown wind waves,the acoustic scattering and frequency shift are not obvious for the sea surface under unsteady wind waves. 展开更多
关键词 high-order Bragg scattering frequency shift low-frequency acoustic field moving rough sea surface
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Impact of surface roughness,surface charge,and temperature on sandstone wettability alteration by nanoparticles
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作者 Bingjun Zhang Kaustubh Rane +1 位作者 Mohammad Piri Lamia Goual 《Petroleum Science》 SCIE EI CSCD 2023年第5期2852-2863,共12页
The wettability of rocks affects the balance between capillary and viscous forces during multiphase flow through porous media,which in turn determines the fluid displacement process governing the recovery of oil from ... The wettability of rocks affects the balance between capillary and viscous forces during multiphase flow through porous media,which in turn determines the fluid displacement process governing the recovery of oil from subsurface formations.In this work,the mechanism of wettability reversal of aged synthetic sandstones by metal oxide nanoparticles(SiO_(2) and Al_(2)O_(3))was investigated with particular focus on the impact of surface roughness,zeta potential,and temperature.The synthetic surfaces were prepared from powders of Berea sandstone with known grain size ranges and their average roughness and roughness ratio were obtained from the 3D surface reconstruction of their microscope images.Each surface was subsequently aged in Permian crude oil to alter its wettability.For surfaces with larger grain sizes and lower surface roughness ratios,the lower capillary pressure allowed stronger oil/surface interactions,leading to enhanced oil-wetness.The wettability alteration effects of nanoparticles were then examined through real-time top view imaging and dynamic front view contact angle experiments.The negatively charged SiO_(2) nanoparticles rapidly reversed the sandstone wettability,indicating their potential applicability as wettability alteration agents.By contrast,the positively charged Al_(2)O_(3) counterpart caused no wettability reversal.The mechanism of wettability alteration was further studied by microscale interaction analyses and nanoscale transmission electron microscopy.Because nanoparticles were only a few nanometers large,the microscale roughness had a negligible effect on the wettability reversal.Instead,the combined effect of van der Waals dispersion forces and surface-charge-induced electrostatic forces were recognized as the two key factors affecting the wettability of sandstone particles.Such interactions may be curbed at elevated temperatures due to a decrease in the zeta potential and colloidal stability of the particles. 展开更多
关键词 WETTABILITY SANDSTONE surface roughness NANOPARTICLE MICROSCOPE Enhanced oil recovery Contact angle Zeta potential
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Unraveling the influence of surface roughness on oil displacement by Janus nanoparticles
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作者 Yuan-Hao Chang Sen-Bo Xiao +2 位作者 Rui Ma Zhi-Liang Zhang Jian-Ying He 《Petroleum Science》 SCIE EI CAS CSCD 2023年第4期2512-2520,共9页
Janus nanoparticles(JNPs)possess great potential in recovering the residual oil from reservoirs,however,the fundamental interaction mechanisms among nanoparticles,the oil,and reservoir wall characteristics remain to b... Janus nanoparticles(JNPs)possess great potential in recovering the residual oil from reservoirs,however,the fundamental interaction mechanisms among nanoparticles,the oil,and reservoir wall characteristics remain to be elucidated.In this work,models of oil trapping grooves with different geometric features are subjected to molecular dynamics simulations for investigating the influences of roughness parameters on oil displacement dynamics by JNPs.Four key surface geometry parameters and different degrees of surface hydrophobicity are considered.Our results indicate that JNPs hold an outstanding performance in displacing residual oil on weakly to moderately hydrophobic surfaces.Overall,smaller entry and exit angles,the larger aspect ratio of the oil trapping grooves,and a bigger tip length of the rough ridges lead to superior oil recovery.Among the key geometric parameters,the aspect ratio of the oil trapping grooves plays the dominant role.These insights about the interaction of surface properties and JNPs and the resulting trapped oil displacement could serve as a theoretical reference for the application of JNPs for targeted reservoir conditions. 展开更多
关键词 Janus nanoparticles Oil displacement Enhanced oil recovery Molecular dynamics simulation rough surface
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Precipitates Generation Mechanism and Surface Quality Improvement for Aluminum Alloy 6061 in Diamond Cutting
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作者 王海龙 DENG Wenping 王素娟 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第1期150-159,共10页
To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the p... To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the precipitates generation of Al6061 on surface integrity and surface roughness.Based on the Johnson-Mehl-Avrami solid phase transformation kinetics equation, theoretical and experimental studies were conducted to build the relationship between the aging condition and the type, size and number of the precipitates for Al6061. Diamond cutting experiments were conducted to machine Al6061 samples under different aging conditions. The experimental results show that, the protruding on the chip surface is mainly Mg_(2)Si and the scratches on the machined surface mostly come from the iron-containing phase(α-, β-AlFeSi).Moreover, the generated Mg_(2)Si and α-, β-AlFeSi affect the surface integrity and the diamond turned surface roughness. Especially, the achieved surface roughness in SPDT is consistent with the variation of the number of AlFeSi and Mg_(2)Si with the medium size(more than 1 μm and less than 2 μm) in Al6061. 展开更多
关键词 Al6061 PRECIPITATES aging treatment diamond cutting surface roughness
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Effects of surface roughness of substrate on properties of Ti/TiN/Zr/ZrN multilayer coatings 被引量:6
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作者 林松盛 周克崧 +6 位作者 代明江 胡芳 石倩 侯惠君 韦春贝 李福球 佟鑫 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第2期451-456,共6页
Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-s... Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-sectional morphology of the obtained multilayer coatings were investigated. The results show that the Vickers hardness of Ti/TiN/Zr/ZrN multilayer coating, with a film thickness of 11.37 μm, is 29.36 GPa. The erosion and salt spray resistance performance of Cr_17Ni_2 steel substrates can be evidently improved by Ti/TiN/Zr/ZrN multilayer coating. The surface roughness of Cr_17Ni_2 steel substrates plays an important role in determining the mechanical and erosion performances of Ti/TiN/Zr/ZrN multilayer coatings. Overall, a low value of the surface roughness of substrates corresponds to an improved performance of erosion and salt spray resistance of multilayer coatings. The optimized performance of Ti/TiN/Zr/ZrN multilayer coatings can be achieved provided that the surface roughness of Cr_17Ni_2 steel substrates is lower than 0.4μm. 展开更多
关键词 Ti/TiN/Zr/ZrN multilayer coatings surface roughness sand erosion resistance corrosion resistance vacuum cathodicarc deposition TIN ZRN
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Shear sliding of rough-walled fracture surfaces under unloading normal stress 被引量:4
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作者 Qian Yin Chun Zhu +5 位作者 Jiangyu Wu Hai Pu Qi Wang Yuanchao Zhang Hongwen Jing Tianci Deng 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第10期2658-2675,共18页
Through high-precision engraving,self-affine sandstone joint surfaces with various joint roughness coefficients(JRC=3.21e12.16)were replicated and the shear sliding tests under unloading normal stress were conducted r... Through high-precision engraving,self-affine sandstone joint surfaces with various joint roughness coefficients(JRC=3.21e12.16)were replicated and the shear sliding tests under unloading normal stress were conducted regarding various initial normal stresses(1e7 MPa)and numbers of shearing cycles(1 e5).The peak shear stress of fractures decreased with shear cycles due to progressively smooth surface morphologies,while increased with both JRC and initial normal stress and could be verified using the nonlinear Barton-Bandis failure criterion.The joint friction angle of fractures exponentially increased by 62.22%e64.87%with JRC while decreased by 22.1%e24.85%with shearing cycles.After unloading normal stress,the sliding initiation time of fractures increased with both JRC and initial normal stress due to more tortuous fracture morphologies and enhanced shearing resistance capacity.The surface resistance index(SRI)of fractures decreased by 4.35%e32.02%with increasing shearing cycles due to a more significant reduction of sliding initiation shear stress than that for sliding initiation normal stress,but increased by a factor of 0.41e1.64 with JRC.After sliding initiation,the shear displacement of fractures showed an increase in power function.By defining a sliding rate threshold of 5105 m/s,transition from“quasi-static”to“dynamic”sliding of fractures was identified,and the increase of sliding acceleration steepened with JRC while slowed down with shearing cycles.The normal displacement experienced a slight increase before shear sliding due to deformation recovery as the unloading stress was unloaded,and then enhanced shear dilation after sliding initiation due to climbing effects of surface asperities.Dilation was positively related to the shear sliding velocity of fractures.Wear characteristics of the fracture surfaces after shearing failure were evaluated using binary calculation,indicating an increasing shear area ratio by 45.24%e91.02%with normal stress. 展开更多
关键词 Unloading normal stress rough fracture surface Shear sliding Normal displacement Shear wear characteristics
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SURFACE ROUGHNESS EVOLUTION AND FORMABILITY OF INTERSTITIAL FREE SHEET STEEL TO GRAIN SIZE AND SHEET THICKNESS 被引量:1
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作者 高霖 童国权 郭勇 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1999年第2期200-203,共4页
Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF she... Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF sheet steel is proportional to effective strain, grain size and inversely proportional to sheet thickness; the larger grain reduces the formability by accelerating the surface roughening rate and enhance formability by raising the workhardening rate, while the latter effect plays the dominate role. The grain size effect on surface roughening and formability is more obvious when the sheets are thinner. 展开更多
关键词 surface roughness PLASTICITY grain size FORMABILITY
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Effect of Surface Roughness on Lubrication Performance of Bump-Type Gas Foil Bearings 被引量:1
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作者 许浩杰 杨泊莘 +1 位作者 李正美 安琦 《Journal of Donghua University(English Edition)》 CAS 2023年第1期45-58,共14页
Taking bump-type gas foil bearings as the research object,a deformation model of bump foil and a thin-plate finite element model of top foil were proposed.By solving Reynolds equation and energy equation,the pressure ... Taking bump-type gas foil bearings as the research object,a deformation model of bump foil and a thin-plate finite element model of top foil were proposed.By solving Reynolds equation and energy equation,the pressure distribution and the temperature distribution of gas films in foil bearings were obtained.Further,a numerical method for calculating the lubrication performance of gas foil bearings with considering the surface roughness was proposed.With a specific example,effects of the surface roughness on the bearing lubrication performance were parametrically studied.The results indicate that rougher journal surface can lead to larger fluctuation of the lubrication performance,while surface roughness of top foil has few effects on the fluctuation.Moreover,the mean values of performance parameters almost remain constant at different values of surface roughness. 展开更多
关键词 foil bearing surface roughness lubrication performance numerical simulation parametric study
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SIMULATION ANALYSIS OF INFLUENCE OF ROAD SURFACE ROUGHNESS ON TYRE DYNAMIC PERFORMANCE IN AUTOMOTIVE BRAKING
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作者 左曙光 张琦 韩柏东 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2000年第1期42-47,共6页
Using a nonlinear time varying tyre model, this paper simulatively analyzes the influence of road surface roughness amplitude and road spatial frequency on automobile ground adhesion ability. The result shows that wi... Using a nonlinear time varying tyre model, this paper simulatively analyzes the influence of road surface roughness amplitude and road spatial frequency on automobile ground adhesion ability. The result shows that with the increase of road surface roughness, the tyre adhesion ability declines, and the automotive braking distance increases. Moreover, the reliability of the nonlinear time varying tyre model in reflecting the influence of the road surface roughness is validated. It is testified that this model is an effective dynamic one in the simulation of automotive braking performance on uneven road. 展开更多
关键词 road surface roughness braking process SIMULATION tyre model
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Effects of surface roughness on bending properties of rolled AZ31 alloy
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作者 Gyo Myeong Lee Jong Un Lee Sung Hyuk Park 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第4期1224-1235,共12页
This study investigated the effects of mechanical-polishing-induced surface roughness and the direction of polishing lines on the bending properties of a rolled AZ31 alloy.To this end,three-point bending tests were pe... This study investigated the effects of mechanical-polishing-induced surface roughness and the direction of polishing lines on the bending properties of a rolled AZ31 alloy.To this end,three-point bending tests were performed on one sample without polishing lines(SS sample)and two samples with polishing lines—one in which the polishing lines were parallel to the rolling direction(RS-RD sample)and the other in which they were parallel to the transverse direction(RS-TD sample).In all three samples,macrocracks were formed in the width direction on the outer surface,where tensile stress was predominantly generated in the longitudinal direction.However,the macrocracks formed in the SS sample were curved because of the merging of uniformly formed fine microcracks,whereas those formed in the RS-TD sample were linear owing to the formation of relatively coarse microcracks along the polishing lines.The bendability of the samples was in the order of SS>RS-RD>RS-TD,and their limiting bending depths were 4.8,4.6,and 4.4 mm,respectively.In the presence of mechanical-polishing-induced surface roughness,polishing lines perpendicular to the direction of the major stress(i.e.,tensile stress along the longitudinal direction)resulted in a greater degree of stress concentration on the outer surface of the bending specimen.This higher stress concentration promoted the formation of undesirable{10–11}contraction and{10–11}–{10–12}double twins—which typically act as crack initiation sites—and thereby facilitated crack generation and propagation.Consequently,the surface roughness caused premature fracture during bending deformation,which,in turn,caused deterioration of the bendability of the rolled Mg alloy. 展开更多
关键词 AZ31 alloy BENDING surface roughness Stress concentration CraCK
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Evaluation of Surface Roughness of Aluminum Alloy in Burnishing Process Based on Chaos Theory
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作者 Zhipeng Yuan Zhenyu Zhou +3 位作者 Zhiguo Jiang Zeyu Zhao Cong Ding Zhongyu Piao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2023年第1期90-103,共14页
Burnishing experiments with different burnishing parameters were performed on a computer numerical control milling machine to characterize the surface roughness of an aluminum alloy during burnishing.The chaos theory ... Burnishing experiments with different burnishing parameters were performed on a computer numerical control milling machine to characterize the surface roughness of an aluminum alloy during burnishing.The chaos theory was employed to investigate the nonlinear features of the burnishing system.The experimental results show that the power spectrum is broadband and continuous,and the Lyapunov exponentλis positive,proving that burnishing has chaotic characteristics.The chaotic characteristic parameter,the correlation dimension D,is sensitive to the time behavior of the system and is used to establish the corresponding relationship with the surface roughness.The correlation dimension was the largest,when the surface roughness was the smallest.Furthermore,when the correlation dimension curve decreases,the roughness curve increases.The correlation dimension and surface roughness exhibit opposite variation trends.The higher the correlation dimension,the lower the surface roughness.The surface roughness of the aluminum alloy can be characterized online by calculating the correlation dimension during burnishing. 展开更多
关键词 Aluminum alloy burnishing Power spectrum Correlation dimension Lyapunov exponent surface roughness
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Influence of Input Factors on Surface Roughness and Material Removal Speed when Wire-EDM a Hardened SKD11 Steel Curve Profile
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作者 Tran Quoc Hung Nguyen Van Trang 《Journal of Environmental Science and Engineering(B)》 2023年第5期220-229,共10页
The goal of this research is to identify the best set of process machining parameters for wire-EDM(Electrical Discharge Machining)cutting of hardened SKD11 steel when machining a curve profile.The multi-objective func... The goal of this research is to identify the best set of process machining parameters for wire-EDM(Electrical Discharge Machining)cutting of hardened SKD11 steel when machining a curve profile.The multi-objective function includes reducing surface roughness and increasing MRR(Material Removal Rate).The optimization process is prepared by using Taguchi method coupled Grey Relational Analysis.The obtained results revealed that Toff has the greatest influence on the average grey value(48.30%),followed by the influence of WF(Wire Feed,15.99%),VM(Cutting Voltage,9.33%),SV(Server Voltage,5.05%),Ton(Pulse on Time,1.81%),while SPD(Cutting Speed)has a negligible effect(0.89%).Moreover,using the optimal set of machining parameters generates in surface roughness of 1.25399mm and MRR of 26.5562 mm^(2)/min.The verification experiment and Anderson-Darling method demonstrate the validity of the proposed model,which can be utilized for estimating surface roughness and MRR. 展开更多
关键词 Wire Electrical Discharge Machining WIRE-EDM surface roughness Material Removal Speed SKD11.
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The Characteristics and Parameterization of Aerodynamic Roughness Length over Heterogeneous Surfaces 被引量:11
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作者 卢俐 刘绍民 +4 位作者 徐自为 阳坤 蔡旭辉 贾立 王介民 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第1期180-190,共11页
Aerodynamic roughness length (Z0m) is a key factor in surface flux estimations with remote sensing algorithms and/or land surface models. This paper calculates ZOrn over several land surfaces, with 3 years of experi... Aerodynamic roughness length (Z0m) is a key factor in surface flux estimations with remote sensing algorithms and/or land surface models. This paper calculates ZOrn over several land surfaces, with 3 years of experimental data from Xiaotangshan. The results show that Z0m is direction-dependent, mainly due to the heterogeneity of the size and spatial distribution of the roughness elements inside the source area along different wind directions. Furthermore, a heuristic parameterization of the aerodynamic roughness length for heterogeneous surfaces is proposed. Individual Z0m over each surface component (patch) is calculated firstly with the characteristic parameters of the roughness elements (vegetation height, leaf area index, etc.), then Z0m over the whole experimental field is aggregated, using the footprint weighting method. 展开更多
关键词 aerodynamic roughness length heterogeneous surfaces FOOTPRINT
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SURFACE ROUGHNESS PREDICTION MODEL FOR ULTRAPRECISION TURNING ALUMINIUM ALLOY WITH A SINGLE CRYSTAL DIAMOND TOOL 被引量:8
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作者 Wang Hongxiang Li Dan Dong shen Precision Engineering Research Institute, Harbin Institute of Technology, Harbin 150001, China 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2002年第2期153-156,176,共5页
A surface roughness model utilizing regression analysis method is developedfor predicting roughness of ultra-precision machined surface with a single crystal diamond tool. Theeffects of the main variables, such as cut... A surface roughness model utilizing regression analysis method is developedfor predicting roughness of ultra-precision machined surface with a single crystal diamond tool. Theeffects of the main variables, such as cutting speed, feed, and depth of cut on surface roughnessare also analyzed in diamond turning aluminum alloy. In order to predict the optimum cuttingconditions during process planning. A lot of experimental results show that the model can predictthe surface roughness effectively under a certain cutting conditions. 展开更多
关键词 surface roughness Regression analysis Diamond turning Diamond tool
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On Sea Surface Roughness Parameterization and Its Effect on Tropical Cyclone Structure and Intensity 被引量:11
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作者 曾智华 Yuqing WANG +2 位作者 端义宏 陈联寿 高志球 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第2期337-355,共19页
A new parameterization scheme of sea surface momentum roughness length for all wind regimes, including high winds, under tropical cyclone (TC) conditions is constructed based on measurements from Global Positioning ... A new parameterization scheme of sea surface momentum roughness length for all wind regimes, including high winds, under tropical cyclone (TC) conditions is constructed based on measurements from Global Positioning System (GPS) dropsonde. It reproduces the observed regime transition, namely, an increase of the drag coefficient with an increase in wind speed up to 40 m s-1 , followed by a decrease with a further increase in wind speed. The effect of this parameterization on the structure and intensity of TCs is evaluated using a newly developed numerical model, TCM4. The results show that the final intensity is increased by 10.5% (8.9%) in the maximum surface wind speed and by 8.1 hPa (5.9 hPa) in the minimum sea surface pressure drop with (without) dissipative heating. This intensity increase is found to be due mainly to the reduced frictional dissipation in the surface layer and little to do with either the surface enthalpy flux or latent heat release in the eyewall convection. The effect of the new parameterization on the storm structure is found to be insignificant and occurs only in the inner core region with the increase in tangential winds in the eyewall and the increase in temperature anomalies in the eye. This is because the difference in drag coefficient appears only in a small area under the eyewall. Implications of the results are briefly discussed. 展开更多
关键词 sea surface roughness tropical cyclone tropical cyclone structure and intensity drag coefficient numerical model
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Wave-Dependence of Friction Velocity, Roughness Length, and Drag Coefficient over Coastal and Open Water Surfaces by Using Three Databases 被引量:8
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作者 高志球 Qing WANG 周明煜 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第5期887-894,共8页
The parameterization of friction velocity, roughness length, and the drag coefficient over coastal zones and open water surfaces enables us to better understand the physical processes of air-water interaction. In cont... The parameterization of friction velocity, roughness length, and the drag coefficient over coastal zones and open water surfaces enables us to better understand the physical processes of air-water interaction. In context of measurements from the Humidity Exchange over the Sea Main Experiment (HEXMAX), we recently proposed wave-parameter dependent approaches to sea surface friction velocity and the aerodynamic roughness by using the dimensional analysis method. To extend the application of these approaches to a range of natural surface conditions, the present study is to assess this approach by using both coastal shallow (RASEX) and open water surface measurements (Lake Ontario and Grand Banks ERS-1 SAR) where wind speeds were greater than 6.44 m s-1. Friction velocities, the surface aerodynamic roughness, and the neutral drag coefficient estimated by these approaches under moderate wind conditions were compared with the measurements mentioned above. Results showed that the coefficients in these approaches for coastal shallow water surface differ from those for open water surfaces, and that the aerodynamic roughness length in terms of wave age or significant wave height should be treated differently for coastal shallow and open water surfaces. 展开更多
关键词 sea surface roughness wave parameter friction velocity PAraMETERIZATION
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Modeling and Evaluating of Surface Roughness Prediction in Micro-grinding on Soda-lime Glass Considering Tool Characterization 被引量:5
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作者 CHENG Jun GONG Yadong WANG Jinsheng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2013年第6期1091-1100,共10页
The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality proce... The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality processing surface. Therefore, a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography is proposed in this paper. The differences of material removal mechanism between convention grinding process and micro-grinding process are analyzed. Topography characterization has been done on micro-grinding tools which are fabricated by electroplating. Models of grain density generation and grain interval are built, and new predicting model of micro-grinding surface roughness is developed. In order to verify the precision and application effect of the surface roughness prediction model proposed, a micro-grinding orthogonally experiment on soda-lime glass is designed and conducted. A series of micro-machining surfaces which are 78 nm to 0.98 ~tm roughness of brittle material is achieved. It is found that experimental roughness results and the predicting roughness data have an evident coincidence, and the component variable of describing the size effects in predicting model is calculated to be 1.5x 107 by reverse method based on the experimental results. The proposed model builds a set of distribution to consider grains distribution densities in different protrusion heights. Finally, the characterization of micro-grinding tools which are used in the experiment has been done based on the distribution set. It is concluded that there is a significant coincidence between surface prediction data from the proposed model and measurements from experiment results. Therefore, the effectiveness of the model is demonstrated. This paper proposes a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography, which would provide significant research theory and experimental reference of material removal mechanism in micro-grinding of soda-lime glass. 展开更多
关键词 micro-grinding tool topography characterization soda-lime glass surface roughness prediction
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