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Letteratura scientifica selezionata sul tema "Friction"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 23 novembre 2024

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Articoli di riviste sul tema "Friction"

Evans, Philip. "Friction on Frictions". Physiotherapy 78, n. 12 (dicembre 1992): 930. http://dx.doi.org/10.1016/s0031-9406(10)60511-1.

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Zhu, Zongxiao, Hui Wang, Zixuan Qiang, Shi Jiao, Linjun Wang, Min Zheng, Shengyu Zhu, Jun Cheng e Jun Yang. "Molecular Dynamics Study on Nano-Friction and Wear Mechanism of Nickel-Based Polycrystalline Superalloy Coating". Coatings 11, n. 8 (26 luglio 2021): 896. http://dx.doi.org/10.3390/coatings11080896.

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In this work, molecular dynamics simulations are employed to study the nanotribological process of nickel-based polycrystalline superalloy coating. A series of simulations were carried out using the method of repeated friction to explore the influence of frictional force, friction coefficient, grinding groove morphology, wear scar depth, debris flow direction, subsurface damage degree and evolution of defects during the nano-friction process. In addition, the change mechanism of different grain sizes on wear scar depth, frictional force, friction coefficient, and internal damage in the repeated friction process is also explored. The results show that the frictional force is related to the direction of the dislocation slip, and that the friction coefficient change is related to the number of repeated frictions. Moreover, it is observed that the grinding ball has a shunting effect on the formed wear debris atoms, and the shunt point is located at the maximum horizontal radius. We reveal that the grain boundary structure has a strengthening effect. When the grinding ball rubs to the grain boundary, the nucleation of dislocation defects inside the workpiece is obviously hindered by it. Simultaneously, we also find that the closer the subsurface is to the bottom of the grinding ball, the greater the degree of damage to the workpiece by friction. Furthermore, with the grain size decreases that the material begins to soften, resulting in a decrease of frictional force, friction coefficient, and smaller defects are formed inside the workpiece. The research of this work can better clarify the microscopic mechanism of the polycrystalline friction process.

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Li, Jing-Ming, Hai-Jun Wei, Li-Dui Wei, Da-Ping Zhou e Ye Qiu. "Extraction of Frictional Vibration Features with Multifractal Detrended Fluctuation Analysis and Friction State Recognition". Symmetry 12, n. 2 (11 febbraio 2020): 272. http://dx.doi.org/10.3390/sym12020272.

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For the purpose of extracting the frictional vibration characteristics of the friction pair during friction and wear in different friction states, the friction and wear tests of friction pair in different friction states were conducted on a testing machine. Higher-dimensional fractal and multifractal characteristics hidden in time series can be examined by multifractal detrended fluctuation analysis (MFDFA) method. The frictional vibration time-domain signals, the friction coefficient signals and the frictional vibration frequency-domain signals were analyzed and multifractal spectra were acquired by using the MFDFA algorithm. According to the spectra, the multifractal spectrum parameters of these signals were calculated to realize the quantitative characterization of frictional vibration characteristics in different friction states. The analysis shows that it is symmetric in the variation trends of the multifractal spectrum parameters of the frictional vibration signals and the friction coefficient data. Based on the multifractal spectrum parameters of frictional vibration, the principal component analysis (PCA) algorithm was applied to establish the friction state recognition method. The results show that the multifractal spectra and their parameters can characterize the frictional vibrations, and the friction state recognition can be realized based on the multifractal spectrum parameters of frictional vibrations.

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Qiao, Yu Lin, Shan Lin Yang, Yan Zang e Xin Yu Dong. "Effects of Ultrasonic Vibration on Tribological Properties of GCr15/45^# Steel Frictional Pairs in Lubricated Sliding Conditions under Various Friction Speed". Advanced Materials Research 338 (settembre 2011): 599–602. http://dx.doi.org/10.4028/www.scientific.net/amr.338.599.

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The effects of friction speed and ultrasonic vibration on friction reduction and anti-wear properties of GCr15/45# steel frictional pairs under oil lubrication were investigated by a modified MFT-R4000 reciprocating friction and wear tester. The mechanism of friction reduction and anti-wear under ultrasonic vibration was discussed. The results showed that, the ultrasonic vibration could influence the friction reduction and anti-wear properties of frictional pairs due to it could reduce the stress between the friction pairs and destroy the oil film on the surface of samples. When the friction frequency was 2Hz，ultrasonic vibration would reduce the friction coefficient and wear volume of the frictional pairs. When the load was 40N, the friction coefficient and wear volume of the frictional pairs attained under ultrasonic vibration decreased 8% and 44% respectively. However, ultrasonic vibration would increase the friction coefficient and wear volume when the friction frequency was 5Hz. When the load was 30N, friction coefficient and wear volume of frictional pairs increased 11% and 74% than that without ultrasonic vibration respectively.

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Fang, Kun. "Frictional Performance of Polyphenyl Ester Modified Polytetrafluoroethylene". Materials Science Forum 1080 (30 gennaio 2023): 33–39. http://dx.doi.org/10.4028/p-g7gf9i.

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This paper mainly studied the coefficient of friction (COF), wear performance and frictional vibration performance of polyphenyl ester modified polytetrafluoroethylene under dry friction and water lubrication friction conditions. Polyphenyl ester modified polytetrafluoroethylene composites were prepared by blending 20% polyphenyl ester with polytetrafluoroethylene, and the COF, wear performance and frictional vibration properties of such composites were tested. The results showed that: (1) Under dry friction conditions, as the specific pressure between the friction pairs increased, the volume of wear and the thickness of the wear increased, the COF decreased at first and then increased, the frictional vibration increased and stabilized after the pressure of 0.5 MPa. (2) Under water-lubricated friction conditions, as the specific pressure between the friction pairs increased, the COF increased, and the frictional vibration increased and stabilized after the pressure of 0.5 MPa; (3) The wear resistance of polyphenyl ester modified polytetrafluoroethylene composite under water-lubricated friction was better than that under dry friction, the COF was less than that under dry friction, and the total level of frictional vibration was slightly lower than that under dry friction. Therefore, in order to reduce frictional vibration and improve service life, the working pressure should be reduced, and the lubrication performance between the friction surfaces should be improved. Under water-lubricated friction, the maximum working pressure of the polyphenyl ester modified polytetrafluoroethylene composite system is recommended not to exceed 0.8 MPa.

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Wang, Tian Guo, X. Y. Liu e J. J. Hua. "Investigation on the Fabrication and Properties of the Cu Base Friction Composites". Materials Science Forum 984 (aprile 2020): 125–30. http://dx.doi.org/10.4028/www.scientific.net/msf.984.125.

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Cu-based friction materials were prepared by powder metallurgy technology. The effect of Fe content on friction and wear properties of Cu-based friction materials has been investigated. The results indicate that Fe content has great effects on the wear ability of Cu-based friction materials. Fe works as frictional component in copper-based friction materials, influening the mechanical and frictional property of materials. With increasing Fe content, the hardness and friction coefficient of Cu-based friction materials stability increase, the wear rate of the friction materials decreases. When Fe content is 6%, the materials posses stably high friction factors, as well as good wear ability.

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Zhang, Zijian, Guangwu Zhou, Peng Li, Luole Du e Min He. "Research on the Vibration Behavior of Ring–Block Friction Pair Made of Materials of Water-Lubricated Rubber Bearing under Special Operating Conditions". Applied Sciences 13, n. 13 (28 giugno 2023): 7676. http://dx.doi.org/10.3390/app13137676.

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A water-lubricated rubber bearing (WLRB) is prone to generate frictional vibration noise under special operating conditions, which seriously affects the acoustic stealth performance of warships and threatens their navigation safety. Meanwhile, the main factor affecting the frictional vibration behavior of a WLRB is the materials of the friction pair. Therefore, this work selects a friction pair composed of a copper ring and a rubber block as the research object and studies the frictional vibration behavior of the ring–block friction pair under low-speed and starting conditions. The real friction coefficient curve is used to establish a transient dynamic finite element analysis model for the ring–block friction pair. The effects of the load, friction coefficient, and Young’s modulus on the frictional vibration behavior under special operating conditions are studied. The analysis’s results show that the frequency of the medium-high frequency friction-induced vibration disappears under low-speed operating conditions when the friction coefficient is below 0.1. During the startup process, even if the friction coefficient is very low, the medium-high frequency friction-induced vibration still exists. The research results provide ideas for future theoretical research and guidance suggestions for engineering practice.

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Fang, Shanglong, Wei Xiao, Kewen Chen e Xuding Song. "Research on the Model for the Friction Coefficient of Resin-Based Friction Material and Its Experimental Verification". Materials 16, n. 13 (3 luglio 2023): 4791. http://dx.doi.org/10.3390/ma16134791.

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Resin-based friction materials have been widely used in the friction braking of automobiles and power machinery. Based on experiments for the variation law of friction and wear morphology, a new model for the friction coefficient of resin-based friction materials was proposed, which includes the effects of both the micro convex body on the surface of the friction material and the frictional film generated during the friction process. This quantitative model of friction coefficient materials was established for the modelling of shear strength, compressive strength, shear strength of the frictional film, contact load and wear morphology. The shear strength, compressive strength and wear morphology of the friction material were adjusted by changing the content of basalt fibers and flaky potassium magnesium titanate. Finally, the accuracy of this quantitative model of friction coefficient was verified through experiments on friction samples with different formulations and by changing the frictional contact load. The results show that the predicted friction coefficient of the model is in good agreement with the experimental friction coefficient, the difference between the upper and lower limits of the forecast is only 5.03% and 2.30%, respectively. Meanwhile, the influence of the ratio of shear strength to compressive strength on the friction coefficient is greater than the proportion of wear morphology. The proposed friction model provides a reference value for the study of new resin-based friction materials.

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Jang, Siyoul. "Manipulating Frictional Performance of Wet Clutch Engagement through Material Properties and Operating Conditions". Lubricants 10, n. 9 (19 settembre 2022): 225. http://dx.doi.org/10.3390/lubricants10090225.

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Wet clutch engagement is mainly influenced by the frictional behaviors between the friction pad and steel plate as well as the lubrication behaviors. A positive μ–V friction coefficient of the wet clutch pad is the most preferable characteristic for improving antishudder behavior. In this study, a wet clutch engagement mechanism is theoretically divided into two major frictional behaviors, namely, direct asperity contact of interacting surfaces and hydrodynamic lubrication, for positive μ–V friction performance. These two behaviors are investigated with regard to both material characteristics of the friction pad–steel plate interactions and hydrodynamic lubrication mechanism. Frictional interactions of the friction pad are analyzed according to the material properties of the friction pad, such as elasticity, permeability, and roughness. Hydrodynamic lubrication, by which the initial period of the engagement is dominantly governed by the waviness of surface shape, is investigated to increase the frictional resistance in the initial stage of engagement relative to that in the final stage of engagement for realizing a positive μ–V friction coefficient. Computational simulations of wet clutch engagement behaviors are performed and compared with each other to obtain positive μ–V friction characteristics of the friction pad.

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Bates, Jo. "The politics of data friction". Journal of Documentation 74, n. 2 (12 marzo 2018): 412–29. http://dx.doi.org/10.1108/jd-05-2017-0080.

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Purpose The purpose of this paper is twofold: first, to further develop Paul Edwards’ concept of “data friction” by examining the socio-material forces that are shaping data movements in the cases of research data and online communications data, second, to articulate a politics of data friction, identifying the interrelated infrastructural, socio-cultural and regulatory dynamics of data friction, and how these are contributing to the constitution of social relations. Design/methodology/approach The paper develops a hermeneutic review of the literature on socio-material factors influencing the movement of digital data between social actors in the cases of research data sharing and online communications data. Parallels between the two cases are identified and used to further develop understanding of the politics of “data friction” beyond the concept’s current usage within the Science Studies literature. Findings A number of overarching parallels are identified relating to the ways in which new data flows and the frictions that shape them bring social actors into new forms of relation with one another, the platformisation of infrastructures for data circulation, and state action to influence the dynamics of data movement. Moments and sites of “data friction” are identified as deeply political – resulting from the collective decisions of human actors who experience significantly different levels of empowerment with regard to shaping the overall outcome. Research limitations/implications The paper further develops Paul Edwards’ concept of “data friction” beyond its current application in Science Studies. Analysis of the broader dynamics of data friction across different cases identifies a number of parallels that require further empirical examination and theorisation. Practical implications The observation that sites of data friction are deeply political has significant implications for all engaged in the practice and management of digital data production, circulation and use. Social implications It is argued that the concept of “data friction” can help social actors identify, examine and act upon some of the complex socio-material dynamics shaping emergent data movements across a variety of domains, and inform deliberation at all levels – from everyday practice to international regulation – about how such frictions can be collectively shaped towards the creation of more equitable and just societies. Originality/value The paper makes an original contribution to the literature on friction in the dynamics of digital data movement, arguing that in many cases data friction may be something to enable and foster, rather than overcome. It also brings together literature from diverse disciplinary fields to examine these frictional dynamics within two cases that have not previously been examined in relation to one another.

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Più fonti

Tesi sul tema "Friction"

Ledezma, Rodríguez Javier Andre. "Technology progress, credit market frictions and labor market friction". Tesis, Universidad de Chile, 2014. http://www.repositorio.uchile.cl/handle/2250/117059.

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Magíster en Economía Aplicada
Este trabajo modela la interacción entre progreso tecnológico (PT), fricciones en el mercado laboral y fricciones en el mercado del crédito, con el objetivo de estudiar cómo la respuesta del mercado laboral frente al aumento del PT se encuentra mediada por el grado de desarrollo del mercado del crédito. La hipótesis principal apunta al hecho que economías con fricciones en el mercado del crédito responden de manera diferente al PT que aquellas economías sin fricciones en dicho mercado, lo que determinaría finalmente el efecto sobre el mercado laboral. Acemoglu (2001) plantea que un mecanismo de este estilo podría servir como explicación alternativa al milagro del empleo en EEUU respecto a Europa durante la década del 80. Con este propósito se desarrolla un modelo teórico de búsqueda para modelar las imperfecciones en ambos mercados, siguiendo el esquema propuesto por Pissarides (1998), aplicado en etapas sucesivas como en Wasmer y Weil (2004). En el modelo, un empresario sigue tres etapas antes de iniciar la producción de su idea de negocio: i) Recauda los fondos necesarios desde el mercado del crédito que le permita iniciar su empresa; ii) Busca un trabajador en el mercado laboral para iniciar la producción de la firma y iii) Produce el bien, el que luego se transa en un mercado de bienes competitivos. Debido a las fricciones, las dos primeras etapas toman tiempo y necesitan recursos. Cuando se inicia la producción, la firma adquiere la tecnología más avanzada disponible cuya productividad es la más alta de la economía. Esta productividad se mantiene constante hasta que el empresario decide adoptar una nueva tecnología con mayor productividad, lo que implica la destrucción de la relación laboral, y también en este modelo, la destrucción de la relación de préstamo. Los principales hallazgos muestran que a medida que crece el PT el valor del trabajo para un empresario disminuye al igual que su vida útil, no obstante, existen dos posibles efectos sobre la congestión de equilibrio del mercado laboral y sobre el desempleo. El sentido de estos efectos depende del costo total involucrado en el proceso de abrir una vacante, el que a su vez se relaciona con las fricciones del mercado del crédito. Un aumento del PT en economías donde el costo total asociado a abrir vacantes es menor que la pérdida del valor del trabajo asociado al PT, incentiva al empresario a destruir las actuales relaciones de trabajo y préstamo, disminuyendo la congestión del mercado laboral. De esta manera, en equilibrio, un aumento del PT induciría mayor reasignación laboral y mayor desempleo. No obstante, economías donde abrir una vacante es un proceso costoso mayor a la pérdida del valor de un trabajo asociada al aumento en el PT, los empresarios prefieren mantener la firma en producción hasta que sea rentable y evitan la transición al mercado del crédito. En equilibrio, la congestión del mercado laboral aumenta y existe una mayor reasignación laboral, sin embargo, el efecto sobre el desempleo depende si el efecto positivo del PT en la congestión de mercado laboral supera, o no, a una fracción del efecto negativo que el PT tiene sobre la vida óptima del trabajo. Respecto a la eficiencia del mercado del crédito, entendida como la habilidad de unir a prestamistas con prestatarios, una economía con una alta probabilidad de encuentro entre estos agentes, presenta menores tiempos de vida de las relaciones de trabajo y una mayor congestión de equilibrio del mercado laboral. Lo primero, dado que encontrar financiamiento se hace más probable, mientras que lo segundo ocurre ya que en equilibrio se ofrecerán más vacantes en busca de trabajadores. No obstante, el efecto sobre el desempleo depende de cómo se balancean estas fuerzas.

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Stratton, Daryl A. "Characterizing the Frictional Interface in Friction Stir Welding". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1757.pdf.

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Omam, Alan Frederic. "Internal friction". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

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Abstract (sommario):

The phenomenon of internal friction most generally defined as the dissipation of mechanical energy inside a gaseous, liquid or solid medium. It is basically different from “friction” in the tribological sense, i.e., the resistance against the motion of two solid surfaces relative to each other (“external friction”).

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Roa, Julio Alberto. "Evaluation of International Friction Index and High-Friction Surfaces". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/36277.

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State highway agencies have an obligation to provide users with optimal surface conditions under various weather conditions throughout the year. A satisfactory pavement surface should exhibit good friction and texture depth to reduce roadway highway accidents. This is why friction is starting to receive increased attention in the pavement management process. There have been numerous research efforts by different countries and agencies to better understand the behavior of different friction testing devices and the influence of texture, speed, and other external conditions on their measurements. The first part of this thesis presents a research effort to compare and harmonize texture and skid resistance measurements taken with various devices on 24 pavement sections with a wide range of textures. Measurements were compared and the International Friction Index (IFI) calculated following PIARC and ASTM steps. The results revealed discrepancies in the IFI values calculated for the different devices, suggesting that the coefficients A, B, and C proposed by PIARC may need to be adjusted for each device considered before the IFI can be implemented by the surface properties consortium participating agencies. In this research the A, B, and C coefficients were then recalculated, and the predicted values of friction using these revised coefficients are presented. The coefficients developed were also used to obtain IFI values for high-friction surfaces (HFS). It has been found that under different conditions, different parameters and coefficients will result. It is strongly recommended equipment comparison experiments (like the NASA and Smart Road programs) continue to better determine the coefficients necessary for harmonization. HFS have emerged as viable high-friction pavement alternatives that mitigate the consequences of driver error, poor geometric alignment of the roadway, and insufficient friction at the tire-pavement interaction, especially during wet weather. This thesis presents a study of the HFS available in the U.S. market and their performance (friction and texture) in different applications, under different weather conditions, and in various locations. This thesis also presents the results of the benefit-cost analysis for the studied HFS.
Master of Science

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Hu, Yuan. "Friction-Stir Riveting: Mechanical Testing of Friction-Stir Riveting". University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430393133.

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REDDA, BOYNA ROHITH. "IMPACT OF FRICTION TEST SCALE ON BRAKE FRICTION PERFORMANCE". OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2051.

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It is well known that the friction performance is a system property. The coefficient of friction and its stability, wear rate and the propensity to vibration and noise are always characteristics of a system and it is not easy to predict their performance based on smaller scale friction tests. This paper discusses the relation between performances of different-scale testers and possibility to model the friction performance of real systems in small simpler testers. It addressed the application of “scaling laws,” the application of typically adopted scaling strategies in friction industry and the testing strategies based on understanding of phenomena on the friction surface and in the friction systems. Full scale AKM standard dyno test and small tester (Bruker UMT) are related and the testing strategy is suggested. It is concluded that in spite of the fact that the scaling and simulations do not allow for a perfect prediction of performance (friction is a system property), it is still possible to make educated decisions on the research and development stage, when proper testing strategy on a smaller scale is adopted.

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Kietzig, Anne-Marie. "Microscopic ice friction". Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23322.

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Microscopic ice friction was studied systematically across all to ice friction relevant friction regimes using several metallic interfaces. A rheometer with a newly designed fixture for friction measurements was used in these studies. The investigations focus on the influence of material properties, such as surface wettability, roughness, surface structure, surface nanopatterning, and thermal conductivity. Using a femtosecond laser process certain dual scale roughness structures were created to mimic the lotus leaf on the surface of inherently hydrophilic metal alloys. After laser irradiation the samples show initially superhydrophilic behavior with complete wetting of the structured surface. However, over time these surfaces become hydrophobic to superhydrophobic. The change in wetting behavior correlates with the amount of carbon found on the structured surface. The explanation for the time dependency of the surface wettability lies in the combined effect of surface morphology and surface chemistry. With regard to ice friction this controlled lotus-like roughness significantly increases the coefficient of friction at low sliding speeds and temperatures well below the ice melting point. However, at temperatures close to the melting point and relatively higher speeds, roughness and hydrophobicity significantly decrease ice friction. This decrease in friction is mainly due to the suppression of capillary bridges. The influence of surface structure on ice friction was also investigated isolated from the effect of surface roughness. It is shown that grooves oriented in the sliding direction also significantly decrease friction in the low velocity range compared to scratches and grooves randomly distributed over a surface. The isolated effect of thermal conductivity on ice friction is investigated by thermally insulating the slider and the friction fixture with fiberglass. A decrease of the friction coefficient in the boundary friction regime and an earlier onset of the mixed friction regime in terms of sliding velocity are reported. Furthermore, the dependence of the ice friction coefficient on sliding velocity is compared for different sliding materials. It was concluded that the influence of thermal conductivity decreases with increasing sliding velocity.

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Chou, Danielle 1981. "Dahl friction modeling". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32826.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (p. 22).
The drive behind improved friction models has been better prediction and control of dynamic systems. The earliest model was of classical Coulomb friction; however, the discontinuity during force reversal of the Coulomb friction model has long been a point of contention since such a discontinuity does not accurately portray the behavior of real systems. Other models have been suggested, but variations of the Dahl solid friction model remain some of the simplest yet most useful. Dahl's original theory proposed that friction behaved as a stress acting upon the quantum mechanical bonds at the interface. Thus, the relationship between frictional force and position would be analogous to a stress-strain curve, complete with hysteresis should there be permanent displacement akin to plastic deformation in materials. This project reviews the variations of Dahl friction models popular in the literature and then demonstrates it both analytically via Matlab and Simulink simulations and experimentally by observing the behavior of a limited angle torque motor.
by Danielle Chou.
S.B.

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Gerde, Eric Stendahl. "Fracture and friction /". Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008334.

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Quignon, Benoit. "Investigations of the frictional behaviour of nanotextured surfaces by friction force microscopy". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685551.

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Friction is omnipresent in our daily life, and although this phenomenon has been studied for centuries, the fundamental understanding on tribological processes as a whole is still lacking. Reducing friction is beneficial in many applications, from mediating wear to improving the life span of devices, hence improving our knowledge of the parameters affecting frictional forces is of paramount importance. In particular, the miniaturisation of modern devices implies that their reliability and durability become friction limited. Recent advances in the fabrication of nanostructured surfaces with tuneable topographic properties, along with advances in metrological tools such as the atomic force microscope (AFM), now provide the means to systematically study friction on well-defined nanostructured surfaces. This research project is focused on the lubricated and un lubricated frictional behaviour of nanotextured surfaces using the AFM with conventional and colloidal probes. The frictional properties of nanotextured surfaces bearing aluminium oxide nanodomes and zinc oxide nanorods of varying topographic properties in air, as well as the frictional properties in aqueous solutions of ionic and nonionic surfactants on flat and textured surfaces of titanium oxide, are reported. The results show that for the nanodomed-textured surfaces, the ancient Amontons laws of dry friction are obeyed; however, the friction coefficient was insufficient to fully characterise the frictional behaviour of such nanotextured surfaces. Pronounced stick-slip frictional characteristics were observed, with the amplitude of the stick-slip varying linearly with the applied load. On nanorod-textured surfaces, the friction-applied load linear relationship was however lost, due to the bending contributions of the rods to the lateral force experienced by the probe. Finally, the results obtained on flat and pillar-textured titanium oxide surfaces showed that ionic surfactants could mediate effective boundary lubrication with the existence of two frictional regimes, due to load- and shear-induced structural changes in the nanofilms of the adsorbed surfactant molecules.

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Più fonti

Libri sul tema "Friction"

Hunter, Samantha. Friction. Toronto, Ontario: Harlequin, 2010.

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Frank, E. R. Friction. New York: Atheneum Books for Young Readers, 2003.

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Mullins, Matt. Friction. New York: Children's Press, 2012.

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Bateman, Claire. Friction. Portland, Or: Eighth Mountain Press, 1998.

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Hewitt, Sally. Friction. North Mankato, MN: Stargazer Books, 2007.

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E, Fitz Ezra, a cura di. Friction. Champaign, Ill: Dalkey Archive Press, 2010.

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Spilsbury, Louise. Friction. London: Evans, 2007.

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Persson, Bo N. J. Sliding Friction. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-04283-0.

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Besdo, Dieter, Bodo Heimann, Manfred Klüppel, Matthias Kröger, Peter Wriggers e Udo Nackenhorst, a cura di. Elastomere Friction. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10657-6.

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Yilbas, Bekir Sami, e Ahmet Z. Sahin. Friction Welding. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-54607-5.

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Capitoli di libri sul tema "Friction"

Ghiotti, Andrea. "Friction". In CIRP Encyclopedia of Production Engineering, 1–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-642-35950-7_16825-1.

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Arnell, R. D., P. B. Davies, J. Halling e T. L. Whomes. "Friction". In Tribology, 27–65. London: Macmillan Education UK, 1991. http://dx.doi.org/10.1007/978-1-349-21387-0_2.

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Muvdi, Bichara B., Amir W. Al-Khafaji e J. W. McNabb. "Friction". In Statics for Engineers, 537–628. New York, NY: Springer New York, 1997. http://dx.doi.org/10.1007/978-1-4612-1922-4_9.

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Arnell, R. D., P. B. Davies, J. Halling e T. L. Whomes. "Friction". In Tribology, 27–65. New York, NY: Springer New York, 1991. http://dx.doi.org/10.1007/978-1-4684-8974-3_2.

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Matsuo, Yoshihiro, Daryl D. Clarke e Shinichi Ozeki. "Friction". In Phenolic Resins: A Century of Progress, 345–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-04714-5_14.

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Straffelini, Giovanni. "Friction". In Springer Tracts in Mechanical Engineering, 21–60. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-05894-8_2.

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Dickson, Peter. "Friction". In Non-Shock Initiation of Explosives, 537–54. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-87953-4_9.

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Emri, Igor, e Arkady Voloshin. "Friction". In Statics, 489–562. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-2101-0_12.

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"Front Matter". In Friction, i—vi. Princeton University Press, 2011. http://dx.doi.org/10.2307/j.ctt7s1xk.1.

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"Natural Universals and the Global Scale". In Friction, 88–112. Princeton University Press, 2011. http://dx.doi.org/10.2307/j.ctt7s1xk.10.

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Atti di convegni sul tema "Friction"

Xu, Y., e K. L. Yung. "Forms of Static Friction, Sliding Friction and Rolling Friction". In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-64050.

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Although, it seems that the concepts of static friction, sliding friction and rolling friction are common knowledges, their real sources are ironically not so clear. Inappropriate descriptions of them may have hampered the theoretical analyses and calculations of the frictions and deterred their applications in real world. In this paper, we are proposing a new method to model the static friction, sliding friction and rolling friction by three mechanical elements: spring, translatory damper and rotary damper respectively. It is shown that proper descriptions of the frictions, e.g. rolling friction, can help in correcting discrepancies in previous research works.

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Vaccaro, R. J. "Friction compensation without a friction model". In 2012 American Control Conference - ACC 2012. IEEE, 2012. http://dx.doi.org/10.1109/acc.2012.6315497.

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Li, J., F. Lu, P. Zhao, R. Chen e Y. Lin. "Impact friction test for friction materials". In DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading. Les Ulis, France: EDP Sciences, 2009. http://dx.doi.org/10.1051/dymat/2009033.

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KAZACHKOV, A., YU POPKOV, E. SAVCHENKO, L. DIMITROVA e I. ANIKEEVA. "SCIENCE FRICTION". In Proceedings of the International Conference on Physics Education in Cultural Contexts. WORLD SCIENTIFIC, 2004. http://dx.doi.org/10.1142/9789812702890_0045.

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Goguey, Alix, Deepak Ranjan Sahoo, Simon Robinson, Jennifer Pearson e Matt Jones. "Pulp Friction". In CHI '19: CHI Conference on Human Factors in Computing Systems. New York, NY, USA: ACM, 2019. http://dx.doi.org/10.1145/3290605.3300871.

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Mejtoft, Thomas, Sarah Hale e Ulrik Söderström. "Design Friction". In ECCE 2019: 31st European Conference on Cognitive Ergonomics. New York, NY, USA: ACM, 2019. http://dx.doi.org/10.1145/3335082.3335106.

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Papadopoulos, Despina, Otto von Busch, Erik Sandelin e Magnus Torstensson. "Science friction". In the 2004 conference. New York, New York, USA: ACM Press, 2004. http://dx.doi.org/10.1145/1013115.1013183.

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MELIKIDZE, AKAKII. "QUANTUM FRICTION". In Proceedings of the XVIII Lisbon Autumn School. WORLD SCIENTIFIC, 2001. http://dx.doi.org/10.1142/9789812811455_0019.

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Tucker, Kristen M., e Paul M. McElfresh. "Could Emulsified Friction Reducers Prevent Robust Friction Reduction?" In SPE International Symposium and Exhibition on Formation Damage Control. Society of Petroleum Engineers, 2014. http://dx.doi.org/10.2118/168115-ms.

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Zhu, Y. Elaine, e Steve Granick. "What Causes Low Friction? — What Causes High Friction?" In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-64173.

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The design of tribological interfaces is often motivated by a quest to minimize friction and wear. Among the many strategic design principles that have been developed to this end, the simple idea of decoupling frictional force from normal load is especially attractive. Recent work from this laboratory demonstrates that under certain conditions, it is possible to reduce this coupling significantly with the result that the friction coefficient appears to be very low. However, the materials design requirements to achieve this end are rather stringent. Furthermore, modern methods enable one under some conditions to measure directly the structure and motions of lubricants during tribological sliding.

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Rapporti di organizzazioni sul tema "Friction"

Henein, N. A. Instantaneous engine frictional torque, its components and piston assembly friction. A cura di F. A. Nichols. Office of Scientific and Technical Information (OSTI), maggio 1992. http://dx.doi.org/10.2172/6857779.

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Blau, P. J. Friction microprobe investigation of particle layer effects on sliding friction. Office of Scientific and Technical Information (OSTI), gennaio 1993. http://dx.doi.org/10.2172/7188137.

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Lever, James, Susan Taylor, Garrett Hoch e Charles Daghlian. Evidence that abrasion can govern snow kinetic friction. Engineer Research and Development Center (U.S.), dicembre 2021. http://dx.doi.org/10.21079/11681/42646.

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The long-accepted theory to explain why snow is slippery postulates self-lubrication: frictional heat from sliding melts and thereby lubricates the contacting snow grains. We recently published micro-scale interface observations that contradicted this explanation: contacting snow grains abraded and did not melt under a polyethylene slider, despite low friction values. Here we provide additional observational and theoretical evidence that abrasion can govern snow kinetic friction. We obtained coordinated infrared, visible-light and scanning-electron micrographs that confirm that the evolving shapes observed during our tribometer tests are contacting snow grains polished by abrasion, and that the wear particles can sinter together and fill the adjacent pore spaces. Furthermore, dry-contact abrasive wear reasonably predicts the evolution of snow-slider contact area and sliding-heat-source theory confirms that contact temperatures would not reach 0°C during our tribometer tests. Importantly, published measurements of interface temperatures also indicate that melting did not occur during field tests on sleds and skis. Although prevailing theory anticipates a transition from dry to lubricated contact along a slider, we suggest that dry-contact abrasion and heat flow can prevent this transition from occurring for snow-friction scenarios of practical interest.

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Armstrong, Steven E. Fratricide: Fact or Friction? Fort Belvoir, VA: Defense Technical Information Center, maggio 1999. http://dx.doi.org/10.21236/ada370683.

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Marks, Laurence D. Friction in Full View. Fort Belvoir, VA: Defense Technical Information Center, maggio 2010. http://dx.doi.org/10.21236/ada523369.

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Kalinina, Elena, e Lucas Lujan. Friction Experiment Data Analysis. Office of Scientific and Technical Information (OSTI), gennaio 2023. http://dx.doi.org/10.2172/2432067.

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Jewsbury, P. The WAFTER (Wear and Friction Tester): A Versatile Wear and Friction Tester. Fort Belvoir, VA: Defense Technical Information Center, giugno 1987. http://dx.doi.org/10.21236/ada187596.

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Nichols, F. A., e N. A. Henein. Instantaneous engine frictional torque, its components and piston assembly friction. Final report. Office of Scientific and Technical Information (OSTI), maggio 1992. http://dx.doi.org/10.2172/10146148.

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Fabio Morales, Leonardo, Eleonora Dávalos e Raquel Zapata. Estimating Vacancy Stocks from Aggregated Data on Hires: A Methodology to Study Frictions in the Labor Market. Banco de la República de Colombia, aprile 2023. http://dx.doi.org/10.32468/be.1228.

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We develop a methodology that recovers an estimate of the average stock of vacancies using the information on aggregated hires. We show that our prediction of the vacancy stock is unbiased, and it captures well the level and the dynamics of the United States job opening positions reported in the Job Openings and Labor Turnover Survey. We use the methodology to predict vacancies in Colombia for formal and informal salaried workers; together with unemployment, we estimate Beveridge curves and matching functions by occupations, which allows us to study the nature of the efficiency, frictions, and mismatches for different occupations. We find that the formal labor market of technicians is the most inefficient of them all; this inefficiency comes from the mismatch between the abilities of the workers and the requirement of the vacancies. Reducing friction in this occupation will require education and job-oriented training policies. In contrast, the frictions in the market for unskilled workers come from informational lacks. The reductions of friction, in this case, will come from better intermediation and active search policies.

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Manley, Paul R. Chaos, Clausewwitz, Friction and Command. Fort Belvoir, VA: Defense Technical Information Center, novembre 1998. http://dx.doi.org/10.21236/ada442708.

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