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1
Chui, Ming Wei, You Qian Feng, Wei Wang, Pei Lin Li, and Zheng Chao Li. "Numerical Simulation of Rough Surface with Crossed Texture." Applied Mechanics and Materials 321-324 (June 2013): 196–200. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.196.
Анотація:
To meet the demands for rough surfaces data in the research of surface engineering, contacts characteristic and so on, a new numerical simulation of rough surface is proposed. Based on FFT method, rough surface with single direction texture is simulated with circular cosine-exponent autocorrelation function (ACF), and the generated surface is rotated of different given angles respectively by rotation of reference system, then the rough surface with multi-direction texture is created by synthesizing the rotated surfaces. The simulation results show that, the ACF curves of generated surface is periodic fluctuation decay, and has a good fitting result with the predetermined ACF. The contrast result between simulated surface and measured surface shows the available of the proposed method.
2
Tagawa, Norio, Takefumi Hayashi, and Atsunobu Mori. "Effects of Moving Three-Dimensional Nano-Textured Disk Surfaces on Thin Film Gas Lubrication Characteristics for Flying Head Slider Bearings in Magnetic Disk Storage." Journal of Tribology 123, no. 1 (July 25, 2000): 151–58. http://dx.doi.org/10.1115/1.1326442.
Анотація:
This paper describes the effects of moving three-dimensional nano-textured or patterned disk surfaces on thin film gas lubrication characteristics for flying head slider bearings in magnetic disk storage. In order to perform the most realistic simulation of slider flying characteristics over the textured disk surfaces, the direct numerical simulation method is used, instead of using various averaging techniques. Therefore, a deterministic description of the texture is adopted in this study. A dynamic analysis of the slider responses can be carried out, by solving the air bearing equation based on the linearized Boltzmann equation with the equations of motion of the slider under the excitation of the moving texture simultaneously. The slider’s dynamic responses to moving spaced bumps disk surfaces, including both the circumferentially and radially ridged disk surfaces, are computed systematically and basic slider dynamics over patterned disk surfaces is investigated. The effects of the texture area ratios (= texture width/texture pitch) in the circumferential and radial directions on the slider spacing dynamic modulations as well as the slider static flying characteristics are also studied. Furthermore, the effects of three kinds of texture patterns on the slider flying characteristics are investigated. Considering those simulation results, the design optimization for the texture pattern that minimizes not only the slider static flying height increase but also spacing dynamic modulations is discussed in order to achieve ultra-high density proximity magnetic recording.
3
Mao, Yang, and Zhongwei Yin. "Modeling and experiments of cavitation on a pocket-textured surface." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 1 (June 8, 2019): 94–103. http://dx.doi.org/10.1177/1350650119855903.
Анотація:
A two-dimensional computational fluid dynamics model was developed and an experiment was performed to investigate the role of pocket texture on fully lubricated motion with the cavitation effect. This paper discusses the cavitated simulation models and experiments to describe texture cavitation to solve the lubricating properties of the textured friction pair. The effects of velocity and texture scale on the support force and friction coefficient are discussed. It was found that the results of the two-dimensional computational fluid dynamics model with cavitation are nearly consistent with the experimental results; the hydrodynamic pressure decreased and the sliding speed dropped, and the effect of pressure became highly pronounced with ideal texture size. In addition, the simulation solution can show the internal flow field, and extend the solutions to large-scale textures and multiple textures. Meanwhile, appropriate texture parameters can optimize the friction coefficient and support force. The texture depth ratio plays a more important role on the value of the support force, and the width ratio has a greater influence on the friction coefficient.
4
Söderfjäll, Markus, Roland Larsson, Pär Marklund, and Andreas Almqvist. "Texture-induced effects causing reduction of friction in mixed lubrication for twin land oil control rings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, no. 2 (June 9, 2017): 166–78. http://dx.doi.org/10.1177/1350650117709152.
Анотація:
Piston rings are responsible for a major part of the frictional losses in a heavy-duty diesel engine. Such losses can be reduced by applying texture, such as dimples, on the cylinder liner surface. This paper investigates the effect of such texture on the friction between a land of the oil control ring and a textured cylinder liner via numerical simulation. A simulation model considering inertia and mixed lubrication together with a mass-conserving cavitation model is developed. The model is used to determine the dimple parameters that yield the lowest amount of friction for a specific oil control ring of a heavy-duty diesel engine.
5
Gao, Weimin, Lijing Wang, Jolanta K. Coffey, Hongren Wu, and Fugen Daver. "Finite Element Modelling and Experimental Validation of Scratches on Textured Polymer Surfaces." Polymers 13, no. 7 (March 25, 2021): 1022. http://dx.doi.org/10.3390/polym13071022.
Анотація:
Surface texturing is a common modification method for altering the surface properties of a material. Predicting the response of a textured surface to scratching is significant in surface texturing and material design. In this study, scratches on a thermoplastic material with textured surface are simulated and experimentally tested. The effect of texture on scratch resistance, surface visual appearance, surface deformation and material damage are investigated. Bruise spot scratches on textured surfaces are found at low scratch forces (<3 N) and their size at different scratch forces is approximately the same. There is a critical point between the bruise spot damage and the texture pattern damage caused by continuous scratching. Scratch resistance coefficients and an indentation depth-force pattern are revealed for two textured surfaces. A texture named “Texture CB” exhibits high effectiveness in enhancing scratch visibility resistance and can increase the scratch resistance by more than 40% at low scratch forces. The simulation method and the analysis of the power spectral density of the textured surface enable an accurate prediction of scratches.
6
Tong, Rui Ting, Geng Liu, and Lan Liu. "Studies on Nanoscale Sliding Contacts of Textured Surfaces by Multiscale Method." Applied Mechanics and Materials 155-156 (February 2012): 883–86. http://dx.doi.org/10.4028/www.scientific.net/amm.155-156.883.
Анотація:
Coupled molecular dynamics simulation and finite element method, a multiscale method is used to model nanoscale sliding contacts problems. According to an experimental sample, 4 textured surfaces with different asperity shapes are designed. Through the friction forces comparisons between smooth surface and textured surfaces, the effects of texture shapes are investigated, and 2 better textured surfaces are discovered to reduce friction forces.
7
Jia, Hekun, Zeyuan Zhou, Bifeng Yin, Huiqin Zhou, and Bo Xu. "Influence of microdimple on lubrication performance of textured plunger pump." Industrial Lubrication and Tribology 73, no. 4 (April 6, 2021): 563–71. http://dx.doi.org/10.1108/ilt-07-2020-0259.
Анотація:
Purpose The purpose of this study is to investigate the influence of dimple radius, depth and density on the lubrication performance of the plunger. Design/methodology/approach A lubrication model was adopted to consider eccentricity and deformation during the working process of the plunger, and a rig test was performed to confirm the simulation results. The texture was fabricated using laser surface texturing. Findings The simulation results suggested that when dimple radius or depth increases, oil film thickness of the plunger increases before decreasing, and asperity friction displays an opposite trend. Therefore, appropriate microdimple texture could facilitate lubrication performance improvement and reduce the wear. Microdimples were then lased on the plunger surface, and a basic tribological test was conducted to validate the simulation results. The experimental results suggested that the average friction coefficient decreased from 0.18 to 0.13, a reduction of 27.8%. Social implications The introduction of microdimple on a plunger couple to reduce friction and improve lubrication is expected to provide a new approach to developing high-performance plunger couple and improve the performance of the internal combustion engine. If applied, the surface texture could help reduce friction by around 27% and cap the cost relative to the plugger friction. Originality/value The microdimple texture was introduced into the plunger couple of a vehicle to reduce the friction and improve the performance. Findings suggested that surface texture could be used in the automotive industry to improve oil efficiency and lubrication performance. Peer review The peer review history for this article is available at: http://dx.doi.org/10.1108/ILT-07-2020-0259.
8
Yang, Xiping, Xin Kuang, Jinghu Ji, and Yonghong Fu. "Research on the influence of laser molten pool flow and evaporation on the bump texture forming of aluminum plate surface." Surface Topography: Metrology and Properties 10, no. 1 (March 1, 2022): 015050. http://dx.doi.org/10.1088/2051-672x/ac5f68.
Анотація:
Abstract At present, the research of laser texture mainly focuses on the machining quality and its properties, but the forming mechanism of laser bump texture surfaces is relatively less studied. In this paper, a long pulse laser ablation model was established based on the laser molten pool flow and evaporation phenomena by numerical simulation. And the evolution mechanism of bump texture morphology on metal surface during laser irradiation time was studied. The results show that the bump texture morphology shows edge protrusions and central depressions, and in the cooling stage, under the action of surface tension, the concave and convex height will show a rebound phenomenon. At the same time, the influence of laser parameters on the morphology of laser bump texture was studied by experiments. By comparing the numerical simulation with the experimental results, it can be found that when the laser irradiation time is equal to 0.5 ms, the morphology obtained by numerical simulation is close to the experimental results. In addition, the differences of pressure field and velocity of vaporized metal gas at different time and under different laser power are compared. Finally, the plasma on the surface of aluminum during laser machining captured by a high-speed camera indirectly indicates that the evaporated metal gas ionizes and forms a stable plasma layer floating above the target material.
9
Brenner, Gunther, Ahmad Al-Zoubi, Merim Mukinovic, Hubert Schwarze, and Stefan Swoboda. "Numerical Simulation of Surface Roughness Effects in Laminar Lubrication Using the Lattice-Boltzmann Method." Journal of Tribology 129, no. 3 (March 15, 2007): 603–10. http://dx.doi.org/10.1115/1.2736452.
Анотація:
The effect of surface texture and roughness on shear and pressure forces in tribological applications in the lubrication regime is analyzed by means of lattice-Boltzmann simulations that take the geometry of real surface elements into account. Topographic data on representative surface structures are obtained with high spatial resolution with the application of an optical interference technique. The three-dimensional velocity field past these surfaces is computed for laminar flow of Newtonian fluids in the continuum regime. Subsequently, pressure and shear flow factors are obtained by evaluating the velocity field in accordance with the extended Reynolds equation of Patir and Cheng (1978, ASME J. Tribol., 100, pp. 12–17). The approach allows an efficient determination of the hydrodynamic characteristics of microstructured surfaces in lubrication. Especially, the influence of anisotropy of surface texture on the hydrodynamic load capacity and friction is determined. The numerical method used in the present work is verified for a simplified model configuration, the flow past a channel with sinusoidal walls. The results obtained indicate that full numerical simulations should be used to accurately and efficiently compute the characteristic properties of film flows past rough surfaces and may therefore contribute to a better understanding and prediction of tribological problems.
10
Zhang, G. M., and S. G. Kapoor. "Dynamic Generation of Machined Surfaces, Part 2: Construction of Surface Topography." Journal of Engineering for Industry 113, no. 2 (May 1, 1991): 145–53. http://dx.doi.org/10.1115/1.2899671.
Анотація:
In Part 1 of these two-part papers, a normal distribution model has been formulated to describe the random excitation system present during machining. Part 2 presents a methodology to dynamically generate the surface topography under the random excitation environment through computer simulation. The proposed methodology uses the tool vibratory motion along with the tool geometrical motion to construct the topography of a machined surface. Both experimental and simulation results confirm that when a small feed is used, the influence of the spiral trajectory of tool geometrical motion on the surface generation decays dramatically and the random excitation system, on the opposite, is strengthened playing a significant role in surface texture generation.
11
Chen, Ping, Xiaojie Liu, Mingji Huang, Zhe Shi, and Bin Shan. "Numerical simulation and experimental study on tribological properties of stamping die with triangular texture." Tribology International 132 (April 2019): 244–52. http://dx.doi.org/10.1016/j.triboint.2018.12.025.
12
Li, Chenchen, Xuefeng Yang, Shouren Wang, Yanjun Wang, Chongyang Lu, and Jinlong Cao. "Study on Friction and Lubrication Characteristics of Surface with Unidirectional Convergence Texture." Coatings 9, no. 12 (November 21, 2019): 780. http://dx.doi.org/10.3390/coatings9120780.
Анотація:
In order to study the influence of texture on the wear and lubrication performance of the surface of the tools, three kinds of textures with unidirectional convergence morphology were processed on the surface of the samples, and each texture was designed with different area occupancy ratios. Simulation analysis shows that, owing to the reflow and convection effect of liquid in the texture, the lubricating film flowing through the textured surface has a high hydrodynamic pressure value, and the semicircular ring texture is the most prominent. By comparing the friction coefficient, when the area occupancy ratio of texture on the surface is 10%, the surface of the samples with different morphology has the lowest coefficient of friction; the friction coefficient of the semicircular ring textured surface is especially very low. Surface textures reduce the direct contact area between the friction pairs, and generate dynamic pressure lubrication and secondary lubrication, so that the surface friction coefficient of the samples is obviously reduced. The surfaces of the non-textured samples have abrasive wear and contact fatigue wear, and the surfaces of the textured samples have adhesive wear, abrasive wear, and cavitation.
13
Li, Qian, Yanmin Zhang, Yunhua Wang, Yining Bai, Yushi Zhang, and Xin Li. "Numerical Simulation of SAR Image for Sea Surface." Remote Sensing 14, no. 3 (January 18, 2022): 439. http://dx.doi.org/10.3390/rs14030439.
Анотація:
Based on the simulated signal, a numerical simulation method of synthetic aperture radar (SAR) imaging for time-varying sea surfaces is proposed, which is helpful to study the SAR imaging mechanism of time-varying sea surfaces so as to better extract ocean wave parameters from SAR images. Not only are the modulation of ocean waves, speckle noise, and temporal decorrelation of the small-scale waves considered, but the velocity bunching (VB) effect caused by the motion of large-scale waves is also effectively added to the simulation of the SAR echo signal. To verify the reliability of the simulation method, the simulated SAR images using the parameters of the RADARSAT-2 SAR, the corresponding wind wave information measured by an in-situ buoy, and the reanalysis wave spectra have been compared with the actual RADARSAT-2 SAR images. The comparisons demonstrate that the characteristics of simulated SAR images, such as the intensity distribution and the image spectra, are consistent with those of actual RADARSAT-2 SAR images. Based on the numerical simulation method proposed by us, SAR images of ocean waves for different marine environments and radar platform parameters are simulated. The imaging results indicate that the texture feature of the wind waves would be severely damaged due to the VB effect, while the texture of swells in the simulated SAR images may not be damaged or even becomes clearer. From the simulated SAR image spectrum, it can be found that the azimuth wavenumber is cut off when the VB effect is considered in the simulation process, and the azimuth cut-off wavelength increases with the range-to-velocity ratio.
14
Huang, Yuanding, Xuezeng Zhao, Yunlu Pan, and Khurshid Ahmad. "Simulation of Effective Slip and Drag in Pressure-Driven Flow on Superhydrophobic Surfaces." Journal of Nanomaterials 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/5052602.
Анотація:
The flow on superhydrophobic surfaces was investigated using finite element modeling (FEM). Surfaces with different textures like grooves, square pillars, and cylinders immersed in liquid forming Cassie state were modeled. Nonslip boundary condition was assumed at solid-liquid interface while slip boundary condition was supposed at gas-liquid interface. It was found that the flow rate can be affected by the shape of the texture, the fraction of the gas-liquid area, the height of the channel, and the driving pressure gradient. By extracting the effective boundary slip from the flow rate based on a model, it was found that the shape of the textures and the fraction of the gas-liquid area affect the effective slip significantly while the height of the channel and the driving pressure gradient have no obvious effect on effective slip.
15
Zhang, Bo, Jing Qiu Wang, and Xiao Lei Wang. "The Effect of Elastic Deformation on the Load-Carrying Capacity of Textured Sliding Surfaces." Applied Mechanics and Materials 736 (March 2015): 7–12. http://dx.doi.org/10.4028/www.scientific.net/amm.736.7.
Анотація:
In order to study the differences in load-carrying capacity of surface-textured soft materials and stiff materials, a theoretical hydrodynamic model considering elastic deformation is developed for numerical simulation analysis. Minimum oil film thickness at a certain load is computed as an index to evaluate the load-carrying capacity of textured sliding surfaces made of soft materials and stiff materials. The results show that the elastic modulus affects greatly on the load-carrying capacity. In the case of the surface texture with a dimple aspect of 0.05, textured soft materials has a higher load-carrying capacity than that of the stiff materials. In the case of the surface texture with a dimple aspect of 0.01 and only under high loads, textured stiff materials provides a better load-carrying capacity than that of the soft materials.
16
G�rding, Jonas. "Shape from texture for smooth curved surfaces in perspective projection." Journal of Mathematical Imaging and Vision 2, no. 4 (December 1992): 327–50. http://dx.doi.org/10.1007/bf00121877.
17
Jiao, Yunlong, Xiaojun Liu, and Kun Liu. "Wettability of laser textured surface: a parametric study based on numerical simulation and experimentation." Industrial Lubrication and Tribology 70, no. 6 (August 13, 2018): 977–83. http://dx.doi.org/10.1108/ilt-01-2017-0008.
Анотація:
PurposeDynamic spreading and wetting on the rough surfaces is complicated, which directly affects the fluxion and phrase transition properties of the fluid. This paper aims to enhance our knowledge of the mechanism of micro-texture lubrication from interface wettability and provide some guidance for the practical manufacturing of the surfaces with special wettability and better lubrication characteristics.Design/methodology/approachThe effect of surface topography on the wetting behavior of both smooth and rough hydrophilic surfaces was investigated using a combination of experimental and simulation approaches. Four types of patterns with different topographies were designed and fabricated through laser surface texturing. The samples were measured with a non-contact three-Dimensional (3D) optical profiler and were parameterized based on ISO 25178. Quantitative research on the relevancy between the topography characteristic and wettability was conducted with several 3D topography parameters.FindingsResults show that for the surfaces with isotropic textures, topography with a small skewness (Ssk) and a large kurtosis (Sku) exhibits better wettability and spreading behavior. For the surfaces with anisotropic textures (smaller texture aspect ratio,Str), dominant textures (such as long groove, rectangle) play a significant guiding role in promoting spreading. In addition, the moving mechanism of the triple contact line and anisotropic spreading were also studied using a computational fluid dynamics simulation. The simulation results have a good adherence with the experimental results.Originality/valueMost of the surface characterization methods at present remain at a level that is related to geometric description, and the topography parameters are limited to 2D roughness parameters. So in present study, the relevancy between wettability and 3D surface topography parameters is explored. The authors believe that the current work provides a new viewpoint to the relevancy between surface topography and wettability.
18
Zhang, Lei, Minli Zheng, Wei Zhang, and Kangning Li. "Research on friction and wear characteristics based on different texture angles of milling topography." Surface Topography: Metrology and Properties 9, no. 4 (December 1, 2021): 045054. http://dx.doi.org/10.1088/2051-672x/ac4567.
Анотація:
Abstract In the field of mold manufacturing, the wear resistance of the mold is a key factor affecting the life of the mold. In order to extend the life of the mold, most scholars have invested a lot of research on the surface texture of the mold. This article mainly analyzes the influence of the texture angle of different milling topography on the wear resistance of the mold. First, we studied the formation process of the milling topography, and distinguished the quadrilateral pit topography and the hexagonal pit topography by defining the texture angle. Secondly, we carried out a wear simulation analysis on the slider with a texture angle, and studied the influence of different topography on the wear depth and stress distribution. Finally, with the help of friction and wear experiments, the wear amount of the slider with different texture angles is tested, and the relationship between the texture angle, the wear quality and the friction coefficient is analyzed. The conclusions obtained provide an effective reference for industrial designers to prepare wear-resistant molds.
19
Li, Kangmei, Dalei Jing, Jun Hu, Xiaohong Ding, and Zhenqiang Yao. "Numerical investigation of the tribological performance of micro-dimple textured surfaces under hydrodynamic lubrication." Beilstein Journal of Nanotechnology 8 (November 6, 2017): 2324–38. http://dx.doi.org/10.3762/bjnano.8.232.
Анотація:
Surface texturing is an important approach for controlling the tribological behavior of friction pairs used in mechanical and biological engineering. In this study, by utilizing the method of three-dimensional computational fluid dynamics (CFD) simulation, the lubrication model of a friction pair with micro-dimple array was established based on the Navier–Stokes equations. The typical pressure distribution of the lubricant film was analyzed. It was found that a positive hydrodynamic pressure is generated in the convergent part of the micro-dimple, while a negative hydrodynamic pressure is generated in the divergent part. With suitable parameters, the total integration of the pressure is positive, which can increase the load-carrying capacity of a friction pair. The effects of the micro-dimple parameters as well as fluid properties on tribological performance were investigated. It was concluded that under the condition of hydrodynamic lubrication, the main mechanism for the improvement in the tribological performance is the combined effects of wedging and recirculation. Within the range of parameters investigated in this study, the optimum texture density is 13%, while the optimum aspect ratio varies with the Reynolds number. For a given Reynolds number, there exists a combination of texture density and aspect ratio at which the optimum tribological performance could be obtained. Conclusions from this study could be helpful for the design of texture parameters in mechanical friction components and even in artificial joints.
20
Chen, Shih Huang, Ching Tsung Hung, Chang Hua Yu, Hung Wen Chung, and Chia Hao Chen. "Laser Scan System to Establish 3-D Surface Texture and Predict Friction of Pavement." Applied Mechanics and Materials 145 (December 2011): 339–43. http://dx.doi.org/10.4028/www.scientific.net/amm.145.339.
Анотація:
Friction of pavement is the most popular tropic which is concerned by drivers and engineers, surface texture are also widely regarded as key factor to influence it. The brief object of this study is to establish the relationship between 3 D texture and friction. In the study, the mixtures include Dense Grade Asphalt Concrete (DGAC), Stone Mastic Asphalt (SMA), and Porous Asphalt (PA). High Definition Scan Texture Machine (HDSTM) with 2D Laser CCD was adopted to measure the 2 D texture of Asphalt concrete specimens, and British Portable Tester (BPN) was also used to evaluate friction of various mixture specimen surfaces. The study was attempted to further create initial 3 D model with data of HDSTM and Computer Simulation Program. Correlation coefficients between the ratio of Surface area in unit area (SA/A) and friction was up to 0.8. SA/A could be regards as the best feasible factor to estimate the mixture surface in the ability of skid resistance, and. Based on above results, 3D texture parameter is remarkable for evaluation of friction and is was worthy of further study.
21
Guo, Ya Li, Rachid Bennacer, Sheng Qiang Shen, and Wei Zhong Li. "Simulation of a Liquid Droplet Impinging on a Horizontal Solid Substrate Using Lattice Boltzmann Moment Model." Defect and Diffusion Forum 283-286 (March 2009): 303–8. http://dx.doi.org/10.4028/www.scientific.net/ddf.283-286.303.
Анотація:
The shape and surface texture of a liquid droplet were studied in two-dimension when a droplet impinges on a solid substrate under isothermal condition. The lattice Boltzmann moment model was applied to simulate the fluid dynamics considering the adhesive interaction between fluid particles and surfaces. The results show the influence of wetting on the process and the drop shape. For the hydrophobic surface, the process after impinging may be divided into two stages: the spreading process driven by inertial forces and the subsequent oscillation (recoiling process) driven by surface tension forces. While for the hydrophilic surface, the droplet will only deposits on the surface and there is no the recoiling stage. In addition, the effects of the impinging speed on the shape and texture of the droplet were studied. The spreading speed and the maximum diameter of the spreading droplet increase with the rise of the impinging speed.
22
Hu, Song, Long Zheng, Qinggang Guo, and Luquan Ren. "Influence of Cross-Grooved Texture Shape on Tribological Performance under Mixed Lubrication." Coatings 12, no. 3 (February 24, 2022): 305. http://dx.doi.org/10.3390/coatings12030305.
Анотація:
Surface texture plays an important role in improving the tribological properties of materials. In this paper, the effect of different shapes (i.e., triangle, square, hexagon, round) on the tribological performance of cross-grooved texture was investigated. First, the mixed lubrication condition was used for the pin-on-disc rotating sliding tests. Then, the stress distribution of the four textures was analyzed to better explain the experimental results. Overall, the hexagon-textured specimens exhibited lower friction coefficients than the other shape-textured specimens under the examined conditions. Simulation results indicate that the contact stress can be reduced on the surface of hexagon-textured specimens, and this leads to a better oil film for lubrication. Furthermore, the hydrodynamic lubrication stood out with the increase of speeds to 250 rpm. However, as the test loads further increased, the film thickness decreased, resulting in the increase in the asperity contact areas, which dropped the above advantage of hexagon-textured specimens. This study would be beneficial for the texturing tribological and lubrication design.
23
Liang, Xingxin, Zhenglin Liu, Huanjie Wang, Xuhui Zhou, and Xincong Zhou. "Hydrodynamic lubrication of partial textured sliding journal bearing based on three-dimensional CFD." Industrial Lubrication and Tribology 68, no. 1 (February 8, 2016): 106–15. http://dx.doi.org/10.1108/ilt-04-2015-0055.
Анотація:
Purpose – The purpose of this study is to investigate the effects of partial texture location and dimple depth on load carrying capacity (LCC), friction coefficient and circumferential flow of journal bearing. Design/methodology/approach – Based on the Navier-Stokes equation, the methodology used computational fluid dynamics (CFD). A phase change boundary condition was applied on fluid domain, and the negative pressure at divergent region of oil film was considered. Findings – It has been found that texture located at lubricant inlet area can improve the performance of the bearing, and the effect of shallow dimples is superior to the deep ones. However, the bearing performance will be reduced due to the texture located at the maximum pressure area. When texture is located at the lubricant outlet area, there will be two different situations: the part of the texture located within the oil film divergent area can improve the LCC, while the part that is beyond the divergent region will make the LCC decrease. Originality/value – The lower-half oil film model was established only in this study to analyze the hydrodynamic lubrication performance of partial textured journal bearing, and the lower-half oil film was divided into three parts. A new cavitation algorithm was introduced to deal with the negative pressure. The formula for calculating the friction of liquid film is refined, including the consideration of vapor phase. The simulation results show that the location of partial texture have a great influence on the bearing performance.
24
Tong, Rui-ting, Bin Han, Ze-fen Quan, and Geng Liu. "Molecular dynamics simulation of friction and heat properties of Nano-texture GOLD film in space environment." Surface and Coatings Technology 358 (January 2019): 775–84. http://dx.doi.org/10.1016/j.surfcoat.2018.11.084.
25
Albesa, Alberto G., Andrés A. García Blanco, Débora A. Soares Maia, Jhonny Villarroel-Rocha, José L. Vicente, and Karim Sapag. "Texture and surface sites of treated and as-prepared SWNT using experimental and simulation methods." Adsorption 27, no. 6 (April 19, 2021): 909–23. http://dx.doi.org/10.1007/s10450-021-00317-9.
26
Tong, Ruiting, Zefen Quan, Yangdong Zhao, Bin Han, and Geng Liu. "Influence of Nanoscale Textured Surfaces and Subsurface Defects on Friction Behaviors by Molecular Dynamics Simulation." Nanomaterials 9, no. 11 (November 14, 2019): 1617. http://dx.doi.org/10.3390/nano9111617.
Анотація:
In nanomaterials, the surface or the subsurface structures influence the friction behaviors greatly. In this work, nanoscale friction behaviors between a rigid cylinder tip and a single crystal copper substrate are studied by molecular dynamics simulation. Nanoscale textured surfaces are modeled on the surface of the substrate to represent the surface structures, and the spacings between textures are seen as defects on the surface. Nano-defects are prepared at the subsurface of the substrate. The effects of depth, orientation, width and shape of textured surfaces on the average friction forces are investigated, and the influence of subsurface defects in the substrate is also studied. Compared with the smooth surface, textured surfaces can improve friction behaviors effectively. The textured surfaces with a greater depth or smaller width lead to lower friction forces. The surface with 45° texture orientation produces the lowest average friction force among all the orientations. The influence of the shape is slight, and the v-shape shows a lower average friction force. Besides, the subsurface defects in the substrate make the sliding process unstable and the influence of subsurface defects on friction forces is sensitive to their positions.
27
Aggarwal, Shipra, and R. K. Pandey. "Performance investigation of micro-pocketed textured pad thrust bearing." Industrial Lubrication and Tribology 70, no. 8 (November 12, 2018): 1388–95. http://dx.doi.org/10.1108/ilt-10-2017-0302.
Анотація:
Purpose The purpose of this paper is to conceive a new surface texture incorporating a tiny shape among the micro-pockets (with circular, rectangular, trapezoidal and triangular cross-sections) and dimples (cylindrical, hemispherical and ellipsoidal) for exploring to enhance the maximum possible performance behaviors of sector shape pad thrust bearing. Design/methodology/approach Numerical simulation of hydrodynamically lubricated sector shape textured pad thrust bearing has been presented incorporating thermal and cavitation effects. The coupled solution of governing equations (Reynolds equation, film thickness expression, viscosity–temperature relation, energy equation and Laplace equation) has been achieved using finite difference method and Gauss–Seidel iterative scheme. Findings With new textured pads, higher load-carrying capacity and lower coefficient of friction are obtained in comparison to plain sector shape pad. Texture pattern comprising square cross-sectional pockets yields higher load-carrying capacity and lower coefficient of friction in comparison to other cross-sectional shapes (circular, trapezoidal and triangular) of pockets considered herein. Originality/value This study reports a new texture, which involves micro-pockets of square cross-sectional shapes to improve the performance behavior of sector shape pad thrust bearing. About 75 per cent increase in load carrying capacity and 42 per cent reduction in coefficient of friction have been achieved with pad having new texture in comparison to conventional pad.
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Adresi, Mostafa, and Giuseppe Lacidogna. "Investigating the Micro/Macro-Texture Performance of Roller-Compacted Concrete Pavement under Simulated Traffic Abrasion." Applied Sciences 11, no. 12 (June 19, 2021): 5704. http://dx.doi.org/10.3390/app11125704.
Анотація:
Since the roller-compacted concrete pavement (RCCP) is almost smooth due to roller vibrations in the construction process, the lack of macro-texture prevents it from being used as a final surface. This study has made efforts to improve the RCCP by proposing different scenarios to create new micro-/macro-texture surfaces and investigate their durability and skid resistance under traffic abrasion conditions. To prepare the micro-texture, eight RCCP specimens were cast using various 50–50% mixing proportions, and each of them alone in the form of siliceous and calcareous fine aggregates (natural and manufactured). For the macro-texture, each specimen was textured using such methods as seeding (three cases), stamping (two cases), and brooming (two cases). Since the durable texture should withstand the abrasive traffic flow, the RCCP-surface abrasion resistance was measured by the simulation method proposed in ASTM C944, and their skid resistance was evaluated by measuring the British pendulum test according to ASTM E303 before and after abrasion. The results showed that abrasion resistance of RCCP samples to changes in mixing design and skid resistance to changes in macro-texture have significant changes. In addition, different siliceous-calcareous sand combinations not only made the concrete mix more economical but also improved its performance in case of abrasion and skid resistance. The more was the manufactured sand proportion, the higher the fracture rate was and, hence, the abrasion resistance. Different macro-textures created on RCCP specimens generally showed acceptable skid resistance. In this regard, stamping had the highest mean texture depth (MTD) as well as BPN, and seeding had the lowest.
29
Fan, Lin, Zi-long Deng, Yan He, Xu-long Zhu, Xing-jun Gao, and Zhe Jin. "The effects of micro-texture shape on serrated chip geometry in the hardened steel AISI D2 cutting process." Surface Topography: Metrology and Properties 10, no. 1 (March 1, 2022): 015031. http://dx.doi.org/10.1088/2051-672x/ac58ad.
Анотація:
Abstract Five micro-textures were processed on the rake face of PCBN tools: circular pits, elliptical grooves, transverse grooves, composite grooves, and wavy grooves. The effect of different micro-textures on cutting force, the cutting temperature, the micro-morphology of serrated chips, tool wear and surface roughness were investigated utilizing three-dimensional finite element simulation and cutting tests. The results indicates that micro-textured tools can lower cutting force when compared to non-textured tools, while cutting force varies significantly during the cutting process. Micro-texture can decrease the temperature in the adiabatic shear band, changes the temperature distribution of the rake face, reduce the serrated degree, and increase segmentation frequency. However, it is more prone to cracking. The wear resistance and the surface quality of machined surface of the elliptical grooves and wavy grooves micro-texture are better.
30
Kaneko, Seitaro, and Hiroyuki Kajimoto. "Measurement System for Finger Skin Displacement on a Textured Surface Using Index Matching." Applied Sciences 10, no. 12 (June 18, 2020): 4184. http://dx.doi.org/10.3390/app10124184.
Анотація:
Understanding the relationship between the displacement of the skin when tracing a textured object and the resulting subjective sensations is essential in designing tactile displays. Previous studies observed skin displacement using flat glass plates or uneven surfaces that do not optically interfere with finger surface observations. In contrast, no direct method for observing skin surface displacement on a texture exists. We propose a system that enables observation of the interaction between a textured surface and the skin of the finger using an index-matching technique. In the proposed system, a texture plate is immersed in oil having the same refractive index as the plate, and measurements are made when the interface is nearly optically transparent. Further, printed markers are attached to the skin of the finger, and their movements analyzed using an image-processing algorithm. The system enables spatial measurement of the skin shear and the vibration of the contact area. Evaluation experiments conducted on a 1D textured surface having a pitch of 0.6 mm verify the feasibility of the proposed system. Optical misalignment simulation results indicate that the system is slightly less accurate than type-I mechanoreceptors but can measure skin deformation on a texture and also observe it spatially and temporally.
31
Zhang, Na, Fazhan Yang, Fulin Jiang, and Guohua Liu. "Study of the effect of surface laser texture on tribological properties of cemented carbide materials." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 234, no. 6-7 (January 30, 2020): 993–1006. http://dx.doi.org/10.1177/0954405419896116.
Анотація:
Surface texturing has become a potential method to obtain a low friction coefficient under dry/lubricated conditions for different mechanical product surfaces. The mechanism of friction and wear reduction from a micro-texture on the surface of cemented carbide cutting tools was investigated by dry cutting a titanium alloy. Three kinds of micro-textures, namely, line, sinusoidal and rhombic grooves, with different area occupancy rates were produced by a laser on the cemented carbide surface. Experiments and finite element simulation of ABAQUS were used to investigate the tribological characteristics of micro-textured cemented carbide. The results indicated that the line-textured cemented carbide with an area occupancy rate of 10% showed a low friction coefficient of 0.076, which is approximately 34% of the non-textured sample. Few adhesives appeared on the textured surface, while a large number of adhesives were attached to the smooth surface after 30 min of dry friction between the cemented carbide and the titanium alloy balls. Moreover, among the three textures, the line-groove texture has the smallest friction coefficient and a good anti-wear effect. The results show that the existence of a groove texture can effectively reserve the wear debris, reduce the bond wear and weaken the furrow effect.
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GENTIL, C., E. TOSAN, and M. NEVEU. "MIXED-ASPECT FRACTAL CURVES." Fractals 17, no. 04 (December 2009): 395–406. http://dx.doi.org/10.1142/s0218348x09004582.
Анотація:
The aim of our work is to elaborate a method to build parametric shapes (curves, surfaces, …) with a non uniform local aspect: every point is assigned a "geometric texture" that evolves continuously from a smooth aspect to a rough aspect. We rely on previous work that enables us to represent both smooth and fractal free form curves to propose a formalism based on finite families of iterated function systems that generalizes this previous approach. The principle is to blend shapes with uniform aspects to define a shape with a variable aspect.
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Xiao, Li Xian, Yong Tai He, Jin Hao Liu, and Yue Hong Peng. "Research on Efficiency of Solar Cell Integrated with Energy Management Circuitry on Chip." Applied Mechanics and Materials 667 (October 2014): 396–400. http://dx.doi.org/10.4028/www.scientific.net/amm.667.396.
Анотація:
In photoelectric micro-power supply integrated on chip, the conversion efficiency of solar cell was lower compared with canonical solar cell. In order to improve the conversion efficiency of the solar cell, three technologies (fabricating back surface field, fabricating surfaces texture and reflector) were adopted in integrated process of photoelectric micro-power supply on chip. The relevant theory of the three technologies was introduced. The optimum schedule of the photoelectric micro-power supply integrated on SOI wafer was proposed. The conversion efficiency of solar cells was analyzed by simulation tools (PC1D). The results prove the conversion efficiency of solar cells was improved from 9. 34% to 13.3%.
34
Salisbury, E. J., K. S. Moon, and J. W. Sutherland. "Development of a Microscopic Laser Interferometry System for Precision Surface Measurement." Journal of Engineering for Industry 117, no. 4 (November 1, 1995): 619–24. http://dx.doi.org/10.1115/1.2803541.
Анотація:
A new technique for the evaluation of precision surfaces using laser interferometry is presented. Laser interferometry creates a fringe pattern which contains information about the surface texture of the specimen. The technique presented compares the ideal fringe pattern to the actual fringe pattern to determine the height deviation on the specimen. In this paper, a simulation model is used to predict the fringe pattern for a given surface. The surface topography of a groove on a computer hard disk is then reconstructed from an experimentally obtained fringe pattern. The reconstruction process is verified by comparing the reconstructed surface to a photograph of the actual surface.
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Kim, SungSoo, Sang Yup Lim та Gyeong-Geun Lee. "Effect of β Phase Decomposition on Recrystallization in α-Zr Region in Zr-2.5%Nb Pressure Tube Material". Korean Journal of Metals and Materials 58, № 10 (5 жовтня 2020): 672–79. http://dx.doi.org/10.3365/kjmm.2020.58.10.672.
Анотація:
The effects of β phase decomposition on recrystallization and texture variation in Zr-2.5% Nb alloy pressure tube material were investigated. Isothermal annealing was conducted at 350 to 550 <sup>o</sup>C for 240 hours, and isothermal annealing was performed at 500 <sup>o</sup>C for 240 to 3,000 hours. The recrystallization and texture variation were analyzed by inverse pole figure variation using the XRD and EBSD methods. Annealing in α-Zr region at below 610 <sup>o</sup>C induced recrystallization and texture variation in the α-Zr. These results differ from those from a previous annealing study of the α+β region at 750-830 <sup>o</sup>C. Annealing above 400 <sup>o</sup>C for 240 hours caused β-Zr decomposition into β-Nb. The decomposition of the β-phase by annealing above 475 <sup>o</sup>C caused a contraction of 7.5% in the d(110) spacing in the β-phase, and a reduction in the volume fraction of the β phase by about 80%. It seems that the stress internally formed by the lattice contraction of the β-phase provides the driving force for recrystallization. In addition, it suggests that the newly formed α-Zr produced by β phase decomposition provides new nucleation sites for recrystallization and causes texture variation in the α-Zr. The reason why the recrystallization and the texture variation occurs only in the α-Zr stable region at below 610 <sup>o</sup>C is discussed.
36
Zhao, Yuanfang, and Yang Jianxi. "Influence of interface slip on the surface frictional force of texturing sliding bearing." Industrial Lubrication and Tribology 72, no. 6 (August 23, 2019): 735–42. http://dx.doi.org/10.1108/ilt-01-2018-0032.
Анотація:
Purpose The purpose of this paper is to explore the sensitive parameters affecting the friction resistance of sliding bearings under different interface slip conditions and the influence of the texture position of circular pits on the friction force of sliding bearings. Design/methodology/approach Based on the mechanical equilibrium equation and Newton's viscous fluid mechanics formula and wedge oil film model, the calculation model of sliding bearing friction resistance under interface slip state is established, and the influence of interface slip on friction resistance under different slip conditions is analyzed by means of ANSYS. Friction simulation model of circular pit textured journal bearing under different interface slip conditions. Findings The friction resistance of bearings is mainly determined by journal linear velocity, oil film slip ratio, pressure of inlet and outlet of bearings, oil film thickness and bearing capacity. When both the upper and lower surfaces of the oil film slip, the friction resistance decreases significantly, which is only 4-17 per cent of that without slip. And the friction force of the texture model of circular pit at the exit is better than that at the entrance and the middle of the pit. Originality/value Relevant research results will lay a new theoretical foundation for friction reduction and optimization design of sliding bearings.
37
Li, Yuyu, Bowen Yang, Tingzhuang Han, Zhibing Chu, Chun Xue, Qianhua Yang, Xiaodong Zhao, and Hong Gao. "Numerical study on the plastic deformation behavior of AZ31 magnesium alloy under different loading conditions." Materials Research Express 8, no. 12 (December 1, 2021): 126505. http://dx.doi.org/10.1088/2053-1591/ac3dac.
Анотація:
Abstract Based on the stress characteristics of the instantaneous cross-section deformation of the wall reducing section during the cold rolling of two-roll Pilger pipes, the rectangular samples with 0° and 90° to the extrusion direction (ED) were cut from the extruded AZ31 magnesium alloy bar for 3% pre-deformation test to simulate its stress state equivalently. The sample was then cut from the pre-deformed sample by wire cutting for secondary compression, and the sample that is not pre-deformed is selected. The mechanical behavior and texture evolution of AZ31 magnesium alloy under different loading conditions were respectively studied by EBSD experiment and VPSC simulation. Results show that the true stress–strain curve and texture evolution characteristics of AZ31 magnesium alloy during the secondary compression process are in good agreement with the prediction of the VPSC model. The secondary compression behavior can be effectively explained by the relative activity of the deformation modes. The pre-deformation in the ∥ED (⊥ED) direction is conducive to the shift of the pole density of the {0001} basal surface texture to the positive and negative directions of the ED (TD). The pre-deformed sample exhibits a higher yield strength than the non-pre-deformed sample in the same loading direction. The high ductility of magnesium alloys can be achieved by activating pyramidal 〈c + a〉 slippage.
38
Wen, Chengwei, Xianghui Meng, and Wenxiang Li. "Numerical analysis of textured piston compression ring conjunction using two-dimensional-computational fluid dynamics and Reynolds methods." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, no. 11 (January 31, 2018): 1467–85. http://dx.doi.org/10.1177/1350650118755248.
Анотація:
The Reynolds equation, in which some items have been omitted, is a simplified form of the Navier–Stokes equations. When surface texturing exists, it may unreasonably reveal the tribological effects in some cases. In this paper, both the two-dimensional computational fluid dynamics method, which is based on the Navier–Stokes equations, and the corresponding one-dimensional Reynolds method are adopted to analyze the performance of the textured piston compression ring conjunction. To conduct a comparison between these two methods, the modified Elrod algorithm for Jakobsson–Floberg–Olsson cavitation model is chosen to solve the Reynolds equation. The results show that the Reynolds method is somewhat different from the computational fluid dynamics method in the minimum oil film thickness, pressure distribution, and cavitation at given operating conditions. Moreover, for a low ratio of texture depth to length, the Reynolds equation is still suitable to predict the overall effects of the designed groove textures. The simulation results also reveal that it is not always beneficial for the tribological performance and sometimes may increase the total friction force when the ring is textured.
39
Hu, Langhua, Siyang Yang, and Guo-Wei Wei. "Simulation of Inviscid Compressible Flows Using PDE Transform." Communications in Computational Physics 16, no. 5 (November 2014): 1201–38. http://dx.doi.org/10.4208/cicp.031113.160514a.
Анотація:
AbstractThe solution of systems of hyperbolic conservation laws remains an interesting and challenging task due to the diversity of physical origins and complexity of the physical situations. The present work introduces the use of the partial differential equation (PDE) transform, paired with the Fourier pseudospectral method (FPM), as a new approach for hyperbolic conservation law problems. The PDE transform, based on the scheme of adaptive high order evolution PDEs, has recently been applied to decompose signals, images, surfaces and data to various target functional mode functions such as trend, edge, texture, feature, trait, noise, etc. Like wavelet transform, the PDE transform has controllable time-frequency localization and perfect reconstruction. A fast PDE transform implemented by the fast Fourier Transform (FFT) is introduced to avoid stability constraint of integrating high order PDEs. The parameters of the PDE transform are adaptively computed to optimize the weighted total variation during the time integration of conservation law equations. A variety of standard benchmark problems of hyperbolic conservation laws is employed to systematically validate the performance of the present PDE transform based FPM. The impact of two PDE transform parameters, i.e., the highest order and the propagation time, is carefully studied to deliver the best effect of suppressing Gibbs’ oscillations. The PDE orders of 2-6 are used for hyperbolic conservation laws of low oscillatory solutions, while the PDE orders of 8-12 are often required for problems involving highly oscillatory solutions, such as shock-entropy wave interactions. The present results are compared with those in the literature. It is found that the present approach not only works well for problems that favor low order shock capturing schemes, but also exhibits superb behavior for problems that require the use of high order shock capturing methods.
40
Ramos, A. M., C. Relvas, and J. A. Simões. "The influence of finishing milling strategies on texture, roughness and dimensional deviations on the machining of complex surfaces." Journal of Materials Processing Technology 136, no. 1-3 (May 2003): 209–16. http://dx.doi.org/10.1016/s0924-0136(03)00160-2.
41
de Kraker, Alex, Ron A. J. van Ostayen, A. van Beek, and Daniel J. Rixen. "A Multiscale Method Modeling Surface Texture Effects." Journal of Tribology 129, no. 2 (December 22, 2006): 221–30. http://dx.doi.org/10.1115/1.2540156.
Анотація:
In this paper a multiscale method is presented that includes surface texture in a mixed lubrication journal bearing model. Recent publications have shown that the pressure generating effect of surface texture in bearings that operate in full film conditions may be the result of micro-cavitation and/or convective inertia. To include inertia effects, the Navier–Stokes equations have to be used instead of the Reynolds equation. It has been shown in earlier work (de Kraker et al., 2006, Tribol. Trans., in press) that the coupled two-dimensional (2D) Reynolds and 3D structure deformation problem with partial contact resulting from the soft EHL journal bearing model is not easy to solve due to the strong nonlinear coupling, especially for soft surfaces. Therefore, replacing the 2D Reynolds equation by the 3D Navier–Stokes equations in this coupled problem will need an enormous amount of computing power that is not readily available nowadays. In this paper, the development of a micro–macro multiscale method is described. The local (micro) flow effects for a single surface pocket are analyzed using the Navier–Stokes equations and compared to the Reynolds solution for a similar smooth piece of surface. It is shown how flow factors can be derived and added to the macroscopic smooth flow problem, that is modeled by the 2D Reynolds equation. The flow factors are a function of the operating conditions such as the ratio between the film height and the pocket dimensions, the surface velocity, and the pressure gradient over a surface texture unit cell. To account for an additional pressure buildup in the texture cell due to inertia effects, a pressure gain is introduced at macroscopic level. The method also allows for microcavitation. Microcavitation occurs when the pressure variation due to surface texture is larger than the average pressure level at that particular bearing location. In contrast with the work of Patir and Cheng (1978, J. Lubrication Technol., 78, pp. 1–10), where the microlevel is solved by the Reynolds equation, and the Navier–Stokes equations are used at the microlevel. Depending on the texture geometry and film height, the Reynolds equation may become invalid. A second pocket effect occurs when the pocket is located in the moving surface. In mixed lubrication, fluid can become trapped inside a pocket and squeezed out when the pocket is running into an area with higher contact load. To include this effect, an additional source term that represents the average fluid inflow due to the deformation of the surface around the pocket is added to the Reynolds equation at macrolevel. The additional inflow is computed at microlevel by numerical solution of the surface deformation for a single pocket that is subject to a contact load. The pocket volume is a function of the contact pressure. It must be emphasized that before ready-to-use results can be presented, a large number of simulations to determine the flow factors and pressure gain as a function of the texture parameters and operating conditions have yet to be done. Before conclusions can be drawn, regarding the dominanant mechanism(s), the flow factors and pressure gain have to be added to the macrobearing model. In this paper, only a limited number of preliminary illustrative simulation results, calculating the flow factors for a single 2D texture geometry, are shown to give insight into the method.
42
Wang, Xigui, Jian Zhang, Yongmei Wang, Chen Li, Jiafu Ruan, and Siyuan An. "Research on Meshing Gears CIMT Design and Anti-Thermoelastic Scuffing Load-Bearing Characteristics." Materials 15, no. 6 (March 11, 2022): 2075. http://dx.doi.org/10.3390/ma15062075.
Анотація:
In the process of gear meshing, it is an inevitable trend to encounter failure cases such as contact friction thermal behavior and interface thermoelastic scuffing wear. As one of the cores influencing factors, the gear meshing contact interface micro-texture (CIMT) significantly restricts the gear transmission system (GTS) dynamic characteristics. This subject suggests the contact characteristic model and interface friction dynamics coupling model of meshing gear pair with different CIMT. Considering the influence of gear meshing CIMT on distribution type of hydrodynamic lubricating oil film, contact viscous damping and frictional thermal load, the aforementioned models have involved transient meshing stiffness (TMS) and static transmission accumulated error (STAE). Based on the proposed models, an example verification of meshed gear pair (MGP) is analyzed to reveal the influence of CIMT on the dynamic characteristics of GTS under a variety of micro-texture configurations and input branch power and rated speed/shaft torque conditions. Numerical simulation results indicate that the influence of CIMT on gear dynamic response is extremely restricted by the transient contact regularity of the meshing gear surface. Meshing gears’ dynamic characteristics (especially vibration and noise) can be obviously and effectively adjusted by setting a regular MGP with CIMT instead of random gear surfaces.
43
Chae, Wonkee, Bong-Kyu Kim, Jongbeom Lee, and Jun Hyun Han. "Effects of Initial Precipitate on Shear Deformation during Asymmetric Rolling of Al-Mg-Si Alloy: Texture and Formability." Korean Journal of Metals and Materials 58, no. 10 (October 5, 2020): 703–14. http://dx.doi.org/10.3365/kjmm.2020.58.10.703.
Анотація:
Al-Mg-Si alloy was rolled asymmetrically at several temperatures to apply shear deformation, and the effects of the initial precipitate on shear deformation, texture evolution, formability, and plastic anisotropy were studied. Texture was analyzed using a EBSD, and the formability and plastic anisotropy of the specimen were evaluated using the value and value calculated from the plastic strain ratio (r-value) which was determined from the change in the length of the specimen during tensile deformation. Asymmetric rolling induces a larger equivalent strain than symmetric rolling, and the equivalent strain increases as the asymmetric rolling temperature increases. When a specimen with peak-aged initial precipitates was asymmetrically rolled, less shear deformation occurred at room temperature than in a solution-treated specimen without initial precipitates. In contrast, a larger shear deformation occurred at high temperatures (500°C). With asymmetric rolling at room temperature, the specimens without initial precipitates had higher formability and lower plasticity, while for asymmetric rolling at high temperature, the specimens with initial precipitates had higher formability and lower plastic anisotropy. This is due to the <111>//ND texture, such as {111}<110> and {111}<112> orientation that has similar and high r-values at 0°, 45°, and 90° to the rolling direction, developed by the shear deformation that occurred during asymmetric rolling.
44
Liu, Shuangbiao, Qian Wang, and Stephen J. Harris. "Surface Normal Thermoelastic Displacement in Moving Rough Contacts." Journal of Tribology 125, no. 4 (September 25, 2003): 862–68. http://dx.doi.org/10.1115/1.1574517.
Анотація:
Computing the thermoelastic displacement of three-dimensional stationary or moving bodies subject to frictional heating is an essential numerical procedure for the complex modeling of the contact of tribological components. Surface Roughness inevitably causes the irregularity of the frictional heat distribution, and thus complicates the process of the numerical simulation of contact problems. The surface normal thermoelastic displacement has been studied in previous papers for either stationary bodies with irregularly distributed heat or moving bodies with regularly distributed heat. In this work, irregularly distributed frictional heat is applied on the surface of a moving body. Temperature and surface normal thermoelastic displacement are solved by using an efficient numerical procedure involving the discrete convolution and fast Fourier transform algorithm and frequency response functions. The thermoelastic displacement due to frictional heat that is proportional to the contact pressure is comparable to the elastic displacement caused by the contact pressure and is not sensitive to the roughness texture. The transient performance of multiple heat sources with different shapes, as well as the mutual influence, is also studied.
45
Birster, K., R. Schweitzer, C. Schopphoven, and A. Tschöpe. "Field-induced deformation of ferromagnetic soft nanocomposites." Journal of Physics D: Applied Physics 55, no. 7 (November 12, 2021): 075003. http://dx.doi.org/10.1088/1361-6463/ac33db.
Анотація:
Abstract Uniaxial ferromagnetic Ni nanorods were prepared by the anodic aluminum oxide (AAO) template method. Reversible magnetization changes, measured perpendicular to the texture axis, were analyzed in terms of the Stoner–Wohlfarth model (SW). Using empirical model parameters, a quantitative and consistent description of the orientation- and field-dependent magnetic torque per particle was achieved. The model was extended (eSW) to take into account the local rotation of the magnetic nanorods in a soft-elastic matrix. The nanorods were characterized regarding their size, using transmission electron microscopy (TEM), their magnetic moment and colloidal volume fraction, determined from static field-dependent optical transmission (SFOT) measurements, and their rotational shape factor, obtained from oscillating field-dependent optical transmission (OFOT). The eSW-model was used in the simulation of simple bending and torsion of thin composite filaments. These simulations were compared with experimental results with the focus on the effect of finite magnetic anisotropy and local elastic rotation on the field-induced deformation of soft nanocomposites. The high sensitivity of thin filaments enabled the investigation of torque-induced deformation at nanorod volume density as low as 10−4 at which particle-particle interactions were negligible. In addition, reprogramming of the magnetic texture by magnetization reversal and the resulting modification in the deformation pattern was investigated.
46
Jin, Da, Ke Xiao, Guo Xiang, Yijia Wang, Cheng Wang, and Hang Jia. "A simulation model to comparative analysis the effect of texture bottom shape on wear and lubrication performances for micro-groove water lubricated bearings." Surface Topography: Metrology and Properties 9, no. 2 (April 8, 2021): 025009. http://dx.doi.org/10.1088/2051-672x/abf325.
47
Malavasi, Caroline Veiga, Elisa Maria Macedo, Karoline da Costa Souza, Guilherme Ferreira Rego, Luis Felipe Jochims Schneider, and Larissa Maria Cavalcante. "Surface Texture and Optical Properties of Self-Adhering Composite Materials after Toothbrush Abrasion." Journal of Contemporary Dental Practice 16, no. 10 (2015): 775–82. http://dx.doi.org/10.5005/jp-journals-10024-1756.
Анотація:
ABSTRACT This study evaluated the surface texture and optical properties of two self-adhering composites and a nanofilled composite before and after toothbrush abrasion. Vertise Flow (Kerr), Fusio Liquid (Pentron Clinical) and Filtek Z350 XT (3M ESPE) composites were divided into 3 groups (n = 6). Disks of 12 mm diameter and 2 mm thick were made. All materials were light-cured with a LED light source for 40 seconds. Analyses of surface roughness, gloss retention and color stability were performed 24 hours after light curing and after 20,000 brushing cycles. Data were analyzed with analysis of variance (ANOVA) and Tukey's test (α = 5%). Results Tukey's test ascertained that toothbrush abrasion resulted in rougher and matte surfaces for all composites tested. Filtek Z350 presented better gloss retention after abrasion. On surface roughness evaluation, there was no statistical difference between Fusio Liquid Dentin and Filtek Z350 resins (p > 0.05). Vertise Flow resin showed better color stability (ΔE), than the other two materials. Conclusion Nanofilled material presented better gloss retention but it did not produce the best results in aspects related to surface roughness and color stability compared to self-adhering composites. Clinical significance A simulation of degradation process by using toothbrush abrasion produced a rougher and matte surface in all composites tested. The surface texture was not only related to filler's amount present in materials, but also with the organic matrix composition of them. The results suggested that the constant development of new materials, seeking for a technical simplification, seems an innovative attraction for dentist's clinical routine, even though larger studies are necessary to promote to everyone a better understanding and improvement of action and effectiveness of this new class of materials. How to cite this article Malavasi CV, Macedo EM, da Costa Souza K, Rego GF, Schneider LFJ, Cavalcante LM. Surface Texture and Optical Properties of Self-Adhering Composite Materials after Toothbrush Abrasion. J Contemp Dent Pract 2015;16(10):775-782.
48
Alateyah, A. I., Mohamed M. Z. Ahmed, Majed O. Alawad, Sally Elkatatny, Yasser Zedan, Ahmed Nassef, and W. H. El-Garaihy. "Effect of ECAP die angle on the strain homogeneity, microstructural evolution, crystallographic texture and mechanical properties of pure magnesium: numerical simulation and experimental approach." Journal of Materials Research and Technology 17 (March 2022): 1491–511. http://dx.doi.org/10.1016/j.jmrt.2022.01.088.
49
Wang, Shun, Yuan-zhong Hu, Wen-zhong Wang, and Hui Wang. "Effects of Surface Roughness on Sliding Friction in Lubricated-Point Contacts: Experimental and Numerical Studies." Journal of Tribology 129, no. 4 (March 30, 2007): 809–17. http://dx.doi.org/10.1115/1.2768081.
Анотація:
The objective of the present work is to investigate experimentally and numerically the influences of surface roughness, produced by typical machining processes, on friction performances in lubricated-point contacts. Prior to the full experimental investigation, a series of tests had been conducted to examine the experimental errors, resulting from repeated tests on the same specimen but at different tracks, with different amounts of lubricant supply, or after the sample reinstallation. Then, the effects of amplitude and texture of surface roughness on friction behavior are investigated in rotational and reciprocal-mode tests, respectively. The measured friction, averaged over the repeated tests and plotted as a function of sliding speed, shows Stribeck-type curves, which manifest the transition from full-film, mixed, to boundary lubrication. Results show that the roughness amplitude imposes a strong influence on the magnificence of friction and the route of lubrication transition. It is also observed that transverse roughness would give rise to a smaller friction coefficient than the longitudinal one under the same operating conditions. Moreover, the deterministic numerical solution of mixed lubrication has been extended to evaluate friction between rough surfaces over a wide range of lubrication regimes. The numerical simulation results are compared and agree very well with experiments.
50
McKenna Neuman, Cheryl. "A review of aeolian transport processes in cold environments." Progress in Physical Geography: Earth and Environment 17, no. 2 (June 1993): 137–55. http://dx.doi.org/10.1177/030913339301700203.
Анотація:
Aeolian environments in Canada experience seasonally cold temperatures. The portion of the annual wind transport occurring between late autumn and early spring usually is perceived as trivial because low temperature transport is difficult to measure reliably, particularly in remote northern areas, and because warm climate based semi-empirical wind erosion models are intractable for temperatures below 0°C. Very little is known about the processes contributing to the phenomenal aeolian transport associated with the Pleistocene Epoch, but supply limiting factors were likely as important then as they are in contemporary high latitude environments, although the wind and solar radiation regimes of this glacial period are not exactly replicated. Field and simulation work on the boundary layer and surface controls, which include wind shear velocity, air density, sediment texture, pore water, snow, ice, and vegetation, suggests a complex system of interactions. Frozen and wet surfaces, traditionally viewed as stable, become very active under certain circumstances.