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Статті в журналах з теми "Interfaces à contact intermittent"
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Labardi, M., P. Tripathi, S. Capaccioli, and R. Casalini. "Intermittent-contact local dielectric spectroscopy of nanostructured interfaces." Nanotechnology 33, no. 21 (February 28, 2022): 210002. http://dx.doi.org/10.1088/1361-6528/ac52be.
Повний текст джерелаАнотація:
Abstract Local dielectric spectroscopy (LDS) is a scanning probe method, based on dynamic-mode atomic force microscopy (AFM), to discriminate dielectric properties at surfaces with nanometer-scale lateral resolution. Until now a sub-10 nm resolution for LDS has not been documented, that would give access to the length scale of fundamental physical phenomena such as the cooperativity length related to structural arrest in glass formers (2–3 nm). In this work, LDS performed by a peculiar variant of intermittent-contact mode of AFM, named constant-excitation frequency modulation, was introduced and extensively explored in order to assess its best resolution capability. Dependence of resolution and contrast of dielectric imaging and spectroscopy on operation parameters like probe oscillation amplitude and free amplitude, the resulting frequency shift, and probe/surface distance-regulation feedback gain, were explored. By using thin films of a diblock copolymer of polystyrene (PS) and polymethylmethacrylate (PMMA), exhibiting phase separation on the nanometer scale, lateral resolution of at least 3 nm was demonstrated in both dielectric imaging and localized spectroscopy, by operating with optimized parameters. The interface within lamellar PS/PMMA was mapped, with a best width in the range between 1 and 3 nm. Changes of characteristic time of the secondary (β) relaxation process of PMMA could be tracked across the interface with PS.
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Ayala, Jose R. Ruiz, Kwangjin Lee, Mujibur Rahman, and J. R. Barber. "Effect of Intermittent Contact on the Stability of Thermoelastic Sliding Contact." Journal of Tribology 118, no. 1 (January 1, 1996): 102–8. http://dx.doi.org/10.1115/1.2837063.
Повний текст джерелаАнотація:
In many sliding systems, the sliding surfaces are not coextensive, so that points on one surface experience alternating periods of contact and separation. This intermittent process can be expected to influence the sliding speed at which the system is susceptible to frictionally-induced thermoelastic instability (TEI). This question is explored in the context of a simple system consisting of a rotating thin-walled cylinder whose end face slides against a rigid surface. The results show that at low Fourier number—i.e., when the frequency of the process is high compared with the thermal transient of the system—only the time-averaged frictional heat input is important and the critical speed is an inverse linear function of the proportion of time in sliding contact. At higher Fourier number, lower critical speeds are obtained, but the dependence on Fourier number is relatively weak.
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Li, Yufeng, and Aric R. Kumaran. "The Determination of Flash Temperature in Intermittent Magnetic Head/Disk Contacts Using Magnetoresistive Heads: Part II—Experimental Investigation." Journal of Tribology 115, no. 1 (January 1, 1993): 179–84. http://dx.doi.org/10.1115/1.2920973.
Повний текст джерелаАнотація:
The flash temperature during intermittent head/disk contacts was measured using specially fabricated magnetoresistive heads. Microasperities were intentionally created on disk substrates, and ZrO2 was sputtered on disc surfaces as overcoat. It was found that with a disk spinning speed of 20 m/s, flash temperature could reach 50 to 100°C for transient contact (head was moving in disk radial direction), but less than 40°C for dwell on track contact (head was stationary). The contact times were in the range from submicroseconds to several microseconds, contact widths on the order of several micrometers, and temperature sensitivity coefficients in the range from 0.15 to 0.7 for a 2.5–μ high magnetoresistive sensor.
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Li, Yufeng, and Aric R. Kumaran. "The Determination of Flash Temperature in Intermittent Magnetic Head/Disk Contacts Using Magnetoresistive Heads: Part I—Model and Laser Simulation." Journal of Tribology 115, no. 1 (January 1, 1993): 170–78. http://dx.doi.org/10.1115/1.2920972.
Повний текст джерелаАнотація:
The feasibility of using a magnetoresistive magnetic head to determine the flash temperature of intermittent magnetic head/disk contacts is investigated. A finite difference model is developed to study the effects of the magnetoresistive sensor height, the contact power intensity and the contact duration on the temperature response characteristics of the magnetoresistive sensor. A pulsed neody-minum:yttrium-aluminum-garnet laser is used as the heat source to simulate the contact and verify the model. The simulation results agree well with the theoretical model. Based on the theoretical model and laser simulation, a temperature sensitivity coefficient ζ is proposed to determine the surface temperature rise.
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Peng, Wei, James Kiely, and Yiao-Tee Hsia. "Wear Analysis of Head-Disk Interface During Contact." Journal of Tribology 127, no. 1 (January 1, 2005): 171–79. http://dx.doi.org/10.1115/1.1843832.
Повний текст джерелаАнотація:
To achieve a higher storage density in a hard disk drive, the fly height of the air bearing slider, as part of the magnetic spacing, has to be minimized. At an ultralow fly height, the intermittent–continuous contact at the head–disk interface (HDI) is unavoidable and directly affects the mechanical and magnetic performance of the hard disk drive, and is of great interest. The HDI wear has a nonlinear and time-varying nature due to the change of contact force and roughness. To predict the HDI wear evolution, an iterative model of Coupled Head And Disk (CHAD) wear, is developed based on the contact mechanics. In this model, a composite transient wear coefficient is adopted and multiple phases of the wear evolution are established. A comprehensive contact stiffness is derived to characterize the contact at the HDI. The abrasive and adhesive wear is calculated based on the extended Archard’s wear law. The plastic and elastic contact areas are calculated with a three-dimensional (3D) sliding contact model. Based on the CHAD wear model, for the first time, the coupling between head and disk wear evolutions is thoroughly investigated. Accelerated wear tests have also been performed to verify the disk wear effect on the slider wear. A wear coefficient drop with time is observed during the tests and it is attributed to a wear mechanism shift from abrasive to adhesive wear. A shift in the type of contact from plastic to elastic accounts for the wear mechanism change.
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Maeno, Takashi, and David B. Bogy. "Effect of the Rotor/Stator Interface Condition Including Contact Type, Geometry, and Material on the Performance of Ultrasonic Motor." Journal of Tribology 116, no. 4 (October 1, 1994): 726–32. http://dx.doi.org/10.1115/1.2927326.
Повний текст джерелаАнотація:
The purpose of this paper is to show the dynamic contact characteristics and the motor performance of several types of ultrasonic motors. First, we compare the performance of “intermittent” and “traveling” contact type ultrasonic motors by using the locally deforming rotor model. We show that the motor performances are the same when the shape of the stator’s amplitude, and the rotor’s interpenetration are the same. Then, we show that the performance of these two types of motors are different according to the effects of inertia and actual three dimensional displacement by using the FE (finite element) analysis. Finally, the effects of the teeth and a surface layer at the contact interface on the performance of the ultrasonic motor, including T-N (torque-speed) characteristics and friction loss, are analyzed.
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Polycarpou, A. A., and A. Soom. "A Two-Component Mixed Friction Model for a Lubricated Line Contact." Journal of Tribology 118, no. 1 (January 1, 1996): 183–89. http://dx.doi.org/10.1115/1.2837076.
Повний текст джерелаАнотація:
A two-component, two-dimensional friction model for a lubricated line contact, operating in boundary and mixed lubrication regimes, is developed. The friction is explicitly decomposed into the solid and the fluid shear components. The solid component is due to the asperity interactions and the fluid shear arises from the lubricant present at the interface. The friction model includes the sliding velocity, the instantaneous separation of the sliding bodies, normal to the sliding direction, the normal load and fluid properties. The model is based on unsteady friction experiments carried out under constant normal loads and time-varying sliding velocities. The model is applied to quasi-steady sliding, unsteady continuous and intermittent sliding, including sticking and momentary reversals of motion. In each case it becomes possible to track the instantaneous fluid shear and solid friction components.
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Lotfi, Mohammad, Saeid Amini, and Hossein Ashrafi. "Theoretical and numerical modeling of tool–chip friction in ultrasonic-assisted turning." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 4 (November 15, 2018): 824–38. http://dx.doi.org/10.1177/0954408918812271.
Повний текст джерелаАнотація:
Decrease of friction in tool–chip contact zone is a key subject in metal cutting operation. Therefore, effect of ultrasonic vibration in this area is analyzed by using experimental and simulation methods. In this study, a theoretical model is firstly developed based on the shear friction model, and then sticking–sliding contact zones plus their contact lengths are defined in order to simulate conventional and ultrasonic-assisted turning. Accordingly, shear angle, sticky length, and cutting forces were measured in experiments as input parameters for the calculation of friction coefficients. As a result, intermittent contact of vibrated tool decreases the time of thermal conduction in tool–chip interface, resulting in a significant reduction in friction coefficient and contact length, particularly, in sticky region.
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Barber, J. R., T. W. Beamond, J. R. Waring, and C. Pritchard. "Implications of Thermoelastic Instability for the Design of Brakes." Journal of Tribology 107, no. 2 (April 1, 1985): 206–10. http://dx.doi.org/10.1115/1.3261021.
Повний текст джерелаАнотація:
Thermal distortion in brakes due to frictional heating causes localized contact and high temperatures (hot spots) with consequent thermal damage to the sliding components. This paper examines the effect of brake design and operating parameters on the maximum temperature reached. Previous solutions for steady-state sliding are reviewed and the effects of hot spots being in intermittent contact due to the geometric design of the brake are discussed. Approximate solutions for transient thermoelastic contact are extended to the case of uniform deceleration to determine the duration of the stop for which thermoelastic effects will be significant. If the stop is sufficiently slow for hot spots to develop, the temperatures will generally be high. However, high temperatures are also reached in sufficiently rapid stops due to the high rate of energy dissipation. An optimum is found between these extremes.
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Li, Shiqi, and Tianyang Ma. "Dynamic performance fluctuation of solid-lubricated rotating mechanism for intermittent operation caused by launch vibration load." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, no. 4 (July 3, 2017): 401–14. http://dx.doi.org/10.1177/1350650117716371.
Повний текст джерелаАнотація:
Space mechanism is the key to success of long-term space missions. The service life of solid-lubricated space mechanisms is affected by various mechanical loads before in-orbit operation, among which the load caused by the launch vibration is the most severe one. Dynamic performance is an indication of the operating state of solid-lubricated mechanisms. The fluctuation of dynamic performances caused by the load of launch vibration is an unanswered but important question. In this paper, the fluctuation of dynamic performances of solid-lubricated rotating mechanisms for intermittent operation was studied by means of experiments and theoretical analyses. One group of rotating mechanisms for intermittent operation with solid-lubricated ball bearings were subjected to sine sweep tests and random vibration tests, followed by continuous operation test. The dynamic performance of mechanisms was obtained throughout all tests. The other group of mechanisms were studied with continuous operation test only for comparing the effects of vibration on the dynamic performance of mechanisms. At the same time, the sample moments of the dynamic performance of mechanisms were calculated and analyzed. The contact stress in the vibration tests was calculated by the Hertz theory. The fluctuation of the dynamic performances of solid-lubricated rotating mechanisms for intermittent operation caused by the load of launch vibration was then concluded with further discussion.
Дисертації з теми "Interfaces à contact intermittent"
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Cruz, Fierro Oscar Eduardo de la. "Contributions to the Study of Intermittent Contact Haptic Interfaces." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS071.
Повний текст джерелаАнотація:
Les interfaces à retour d'effort sont des systèmes robotisés permettant d'interagir gestuellement de façon naturelle avec des environnements virtuels ou distants. Ces dispositifs sont utilisés dans différents contextes tels que la téléopération (e.g. nucléaire, sous-marine, spatiale), le manufacturing, les jeux vidéo, l'éducation, la médecine ou la rééducation, pour ne citer que quelques exemples. Pour les applications en réalité virtuelle, les utilisateurs manipulent généralement ces interfaces à l'aide d'une poignée qui est reliée mécaniquement au robot. Ce lien a une influence importante puisqu'il conduit l'utilisateur à ressentir la présence du robot même en espace libre (frottements, vibrations, inertie de la structure mécanique du robot), ce qui réduit le réalisme de l'interaction. Les interfaces à contacts intermittents (CI) constituent une alternative prometteuse pour essayer de surmonter ces inconvénients. Elles proposent de suivre les mouvements de l'utilisateur à faible distance en espace libre et de ne venir à son contact que lorsque l'on veut appliquer un retour d'effort. Elles visent de cette façon à améliorer le réalisme des interactions. Cette thèse s'intéresse à l'étude et à l'amélioration des performances d'une telle interface CIForce feedback interfaces are robotic systems allowing natural motion interactions with virtual or remote environments. They are employed in several domains such as remote handling (e.g. nuclear, subsea, space), manufacturing, entertainment, education, medicine and rehabilitation, just to mention the most popular. In virtual reality (VR) applications, the user typically holds a handle that is mechanically linked to the end-effector of the robot. This link has a non-negligible influence since the presence of the robot can be felt (friction, inertia and vibrations of the mechanical structure) even in free space, decreasing the realism of the interaction. Intermittent-contact haptic interfaces (IC-HIs) represent a promising approach to cope with this issue. These interfaces track and closely follow (without contact) the user movements in free space and come to his/her contact only when force feedback is required. This way IC interfaces aim to improve the realism of the interactions. The thesis presented concerns the study and improvement of such IC-His
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Gonzalez, Franck. "Contributions au développement d'une interface haptique à contacts intermittents." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066068/document.
Повний текст джерелаАнотація:
Les interfaces haptiques permettent à un opérateur d'interagir avec un environnement virtuel ou distant via le sens du toucher.La majorité des interfaces de l'état de l'art restent au contact de l’utilisateur pendant toute la durée de la manipulation. La liaison permanente entre le robot et l’opérateur nuit à la qualité de l’interaction, notamment en réduisant la transparence en espace libre. Ce problème est d’autant plus prégnant dans le cadre des interfaces haptiques dextres.Cette thèse a pour objectif d'étudier la possibilité d'augmenter la transparence et le réalisme de l'interaction à travers le développement d’interfaces à contacts intermittents. Il s’agit de déconnecter le robot de l'utilisateur lorsqu’aucun contact avec l’environnement n’est nécessaire. Un état de l’art des performances de la manipulation humaine, des interfaces haptiques dextres ainsi que des travaux relatifs au contact intermittent, est d’abord présenté. Un effecteur plan pour le contact intermittent est ensuite conçu. Il est installé à l’extrémité distale d'une interface haptique et plusieurs solutions sont envisagées pour sa loi de commande. Les performances de dix utilisateurs sont comparées dans le cadre d'une tâche de détection de contact en utilisant d'une part l'effecteur adapté au contact intermittent, d'autre part une interface haptique classique. L'élaboration d'une interface permettant une interaction plus naturelle avec l'environnement est ensuite initiée par l'élaboration d'une méthodologie de choix des zones de contact de la main à prendre en compte dans la conception d'une interface haptique. Des perspectives sont finalement données quant à l'extension de ces résultats à une interface haptique dextre à contacts intermittentsHaptic interfaces allow an operator to interact with a virtual environment through the sense of touch. Nowadays, most existing interfaces are mechanically connected to the user's hand throughout the simulation. Therefore he or she interacts with the virtual environment by means of a handle. Thus the interaction is neither natural nor intuitive, and the permanent connection between the robot and the operator is the source of perturbations which prevent the interaction from being perfectly transparent and realistic. The goal of this study is to increase transparency as much as possible by disconnecting the robot from the user when s/he is not in contact with the virtual environment, through the design of a dexterous haptic interface allowing for a more natural interaction than with a classical interface taking into account only one contact point. A state-of-the-art of dexterous haptic interfaces and another for intermittent contact devices are first gathered, and the human performances that should be taken into account for the design of a dexterous haptic interface are analysed. A bidirectional end-effector for intermittent contact is then devised. It is set up at the tip of a haptic interface and several solutions are tested for its control. The performances of six users are compared on the context of a contact detection task, first using the intermittent contact end-effector, then using a classical haptic device. A methodology for the choice of the hand contact areas that should be taken into account in the design of a dexterous haptic interface to enhance the naturalness of the interaction is proposed. Finally, some perspectives are given as for the extension of this study for the design of a dexterous encounter-type haptic interface
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Mercado, Garcia Victor Rodrigo. "Contribution to the Study of Usability and Haptic Feedback of Encountered-Type Haptic Displays." Thesis, Rennes, INSA, 2021. https://tel.archives-ouvertes.fr/tel-03789676.
Повний текст джерелаАнотація:
Les interfaces à contact intermittent (ICIs) sont des dispositifs robotisés qui suivent la main de l'utilisateur et se placent en position de rencontre lorsque l'utilisateur souhaite toucher des objets dans une réalité virtuelle (RV) immersive. Malgré ces avantages, plusieurs défis doivent encore être résolus en matière d'utilisabilité et de retour haptique. Cette thèse présente une série de contributions pour tirer profit des ICIs à travers des axes de recherche l'utilisabilité et le retour haptique.La première contribution dans l'axe de l'utilisabilité a étudié la conception de techniques de sécurité pour les ICIs basés sur le retour visuel. Ensuite, une série de techniques d'interaction pour l'exploration de surface avec les ICIs est présentée. Ces techniques ont exploré plusieurs combinaisons de facteurs liés au contrôle des ICIs afin de donner aux utilisateurs la sensation de toucher une grande surface dans la RV.Concernant l'axe du retour haptique, nous présentons une approche pour le rendu de grandes surfaces multi-texturées. Cette approche est basée sur un accessoire cylindrique rotatif, multi-texturé, attaché à l'effecteur d'un ICIs. Finalement, la thèse présente une contribution à la manipulation d'objets dans la RV en utilisant un objet tangible détachable et un ICIs. Cette contribution permet de créer, détruire et reconfigurer des objets tangibles dans des environnements virtuels immersifsEncountered-Type Haptic Displays (ETHDs) are robotic devices that follow the users' hand and locate themselves in an encountered position when users want to touch objects in immersive virtual reality (VR). Despite these advantages, several challenges are yet to be solved in matters of usability and haptic feedback. This thesis presents a series of contributions to leverage ETHDs through research axes for both usability and haptic feedback.The first contribution in the usability axis studied the design of safety techniques for ETHDs based on visual feedback. Then, a series of interaction techniques for surface exploration with ETHDs is presented. These techniques explored several combinations of factors related to ETHD control to give users the sensation of touching a large surface in VR.Concerning the haptic feedback axis, we introduce an approach for large, multi-textured surface rendering. This approach is based on a rotating, multi-textured, cylindrical prop attached to an ETHD's end-effector. Finally, the thesis presents a contribution to object manipulation in VR using a detachable tangible object and an ETHD. This contribution permits creating, destroying and reconfiguring tangible objects in immersive virtual environments
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Gibbins, Josh. "Thermal Contact Resistance of Polymer Interfaces." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2856.
Повний текст джерелаАнотація:
In this study an experimental program was carried out to determine the thermal contact resistance at polymer interfaces. Specifically, a polycarbonate to stainless steel interface along with a polycarbonate to polycarbonate interface were investigated. The thermal contact resistance at a stainless steel to stainless steel interface was also investigated for comparison purposes. Experimental data was obtained over a pressure range of approximately 600 - 7000 kPa, in a vacuum environment. The experimental data was compared to the CMY plastic contact model, the Mikic elastic contact model and the SY elasto-plastic contact model to investigate the ability of such established thermal contact models to predict the thermal contact resistance at polymer interfaces. Based upon predictions made in regards to the mode of deformation of the asperities on the contacting surfaces the appropriate contact model showed good agreement with the experimental data for the stainless steel-stainless steel data set and the polycarbonate-stainless steel data sets. There was poor agreement between the all three contact models and the experimental data for the polycarbonate-polycarbonate data sets. It was determined that uncertainties in the proposed experimental method prevented an accurate measurement of the thermal contact resistance values for the polycarbonate-polycarbonate data sets.
The purpose of this investigation was to extend the use of established thermal contact models to polymer interfaces and to provide a comparison between the thermal contact resistance values of metal and polymer interfaces.
Thermal contact resistance for the polymer to metal interface was shown to be predicted by the Mikic elastic contact model in comparison to the metal to metal interface which was shown to be predicted by the CMY plastic contact model. The thermal contact resistance for a polymer interface was found to be on the same order as a metal interface.
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Reshamwala, Chetak M. (Chetak Mahesh) 1979. "Contact resistance in RFID chip-antenna interfaces." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8193.
Повний текст джерелаАнотація:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (p. 21).
The purpose of this study was to determine a force-deflection relationship and a force-contact area relationship between a flat planar solid and a spherical solid in terms of material and surface properties of the two bodies. This relationship was determined and it was discovered that the force was directly proportional to both the deflection and contact area. This information is useful in the design and performance of RFID chips. The RFID chip-antenna interface is the area of greatest power loss in the system, and by determining a relationship to increase the contact area in that region, the power loss to the antenna can be reduced. Moreover, an analysis including asperities on the micro scale geometry of the solids was conducted. In the final approach to the problem, a random distribution of asperity types was analyzed. An expression was derived for the total force applied in terms of a given deflection and a range of asperity radii of curvature. A three-dimensional graph was created to show how each of these variables depends on the each other when asperities exist. This relationship is very significant, because it can be used to improve current RFID chip technology to achieve better performance. This expression can also be used to determine specifications in the manufacturing process to achieve a certain deflection or area of contact between the contacting bodies, thereby improving the current manufacturing process.
by Chetak M. Reshamwala.
S.B.
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Dang, Viet-Hung. "Dynamique des interfaces multicontact." Thesis, Ecully, Ecole centrale de Lyon, 2013. http://www.theses.fr/2013ECDL0016/document.
Повний текст джерелаАнотація:
Le bruit de frottement de deux surfaces rugueuses est dû à la vibration verticale engendrée par les impacts inter-aspérités de deux solides glissants. Il relève de la physique des interfaces multicontact dont les propriétés sont encore largement méconnues. L'objet de cette thèse est de comprendre les mécanismes de transfert d'énergie et de génération des vibrations à l'œuvre à l'interface entre deux surfaces rugueuses en glissement relatif. Ces interfaces présentent des spots de contact qui se renouvellent très rapidement mais dont la physique statistique reste à découvrir. Un outil numérique est spécialement développé pour étudier efficacement ce phénomène aux échelles microscopique et macroscopique. Les simulations sont effectuées à l'aide de centres de calcul haute performance à Lyon. Elles ont mené aux conclusions suivantes. Le niveau de la vibration Lv (dB) est une fonction croissante du logarithme de la rugosité de surface Ra et de la vitesse de glissement V, ce qui est en accord avec les résultats expérimentaux issus de la littérature. De plus, grâce à cet outil numérique, on a pu analyser précisément les chocs entre surfaces définis à partir de l'évolution temporelle de la force de contact. Leur durée est de l'ordre de 0.1 ms, la force maximale de contact peut atteindre 100 fois le poids propre du solide glissant, et le nombre de chocs est de l'ordre de 10000 par seconde pour une surface de l'ordre de 4 cm2. Les chocs sont donc des excitations transitoires brèves mais nombreuses et intenses. Ces chocs se comportent comme les sources d'énergie vibratoire qui sont responsables d'un transfert d'énergie à l'interface. C'est en effet la transformation de l'énergie cinétique du mouvement solide glissant en énergie vibratoire qui est responsable du bruit de frottementThe friction noise between two rough surfaces is caused by the vertical vibration generated by inter-asperity impacts of sliding solids. This phenomenon involves the physics of multicontact interfaces, a field which is largely unknown. The purpose of this thesis is to understand the mechanisms of noise generation and the energy transfer process between two rough surfaces in sliding contact. The contact spots in the interface are rapidly renewed during the movement in a random fashion but their statistical properties remain to be discovered. A numerical tool is developed in order to efficiently study this phenomenon at both macroscopic and microscopie scales. The simulations are carried out thanks to the high performance computing centre in Lyon. This study leads to the following conclusions. The vibration level Lv (dB) is an increasing logarithm function of surface roughness Ra and sliding velocity V. This statement is consistent with experimental results available in the literature. Moreover, we can analyze precisely the asperity shocks which are defined from the time evolution of the contact force. The shock duration is of the order of 0.1 ms, the maximal contact force can reach to 100 times the weight of sliding solid, and the shock rate is of the order of 10000 for a surface of 4 cm2 . The asperity shocks are transient excitations, brief but abundant and intensive. These shocks behave like vibrational energy sources and are responsible of the energy transfer in the interface. This is the transformation process of kinetic energy to vibrational energy which is responsible of friction noises
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Chabrier, Anthony. "Etude théorique et expérimentale d'une interface à retour d'effort augmenté." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066383/document.
Повний текст джерелаАнотація:
Les interactions physiques comportent divers gestes dextres et sont sources d’échanges d’informations très variées. Différentes interfaces haptiques ont été développées pour reproduire ces mouvements dextres et ces interactions. Cependant il est impossible actuellement de concevoir une interface simulant tous les types d’interactions avec un retour haptique réaliste. Je propose d’identifier les interactions les plus importantes et les zones de la main les plus intéressantes à stimuler, et ensuite d’étudier comment associer certains dispositifs pour améliorer le ressenti de l’utilisateur. Il semble intéressant de développer une interface se concentrant sur : la transition entre les mouvements de l’utilisateur en espace libre et au contact d’un objet, le retour d’effort, et enfin la déformation locale et globale de la pulpe, et ce sur 4 zones : les phalanges distales du pouce, de l’index et de l’annulaire, et le côté extérieur de l’index. Afin de rendre cela réalisable dans le cadre d’une thèse, j’ai entrepris de développer une interface à retour d’effort à contacts intermittents sur le pouce et l’index, tout en prenant en compte l’ajout futur d’un retour plus complet. Pour cela, j’ai tout d’abord élaboré un effecteur instrumenté permettant d’acquérir, sans contact, la position de la dernière phalange d’un doigt en 6D. Puis j’ai dimensionné une interface de type gant à deux doigts, capable de déplacer, en 6D, ces effecteurs dans l’ensemble de l’espace de travail des doigts et de générer un retour d’effort quand cela est nécessaire. Enfin j’ai étudié la commande de ce système lors de ses différentes phases de fonctionnement et ses performances ont été évaluéesPhysical interactions involve highly dexterous movements and exchanges of diverse information. Numerous haptic interfaces were developed with the aim to reproduce these dexterous gestures and each of these interactions. However, it is technically impossible to date to design an interface simulating all of them with a realistic haptic feedback.I propose to identify the most important interactions and the hand areas the most interesting to stimulate, and then to study how associate different devices to improve the feeling of an operator. I decided to focus on: the transition between user’s movements in free space and in contact with an object, force feedback, and finally local and global deformation of the fingers’ pulp, with an emphasis on the four following areas: distal phalanges of the thumb, index and middle finger, plus the external side of the index finger. To make this possible during a PhD, I finally decided to focus on an intermittent contact force feedback interface for the thumb and index fingers, by taking into account the future integration of more complete feedback. Therefore, I first developed instrumented end-effectors able to remotely measure the 6D configuration of the distal phalanx of the fingers without any contact with them. Then I dimensioned and designed a glove-type haptic interface with two fingers. This device allows controlling the position and orientation of the intermittent contact end-effectors in 6D throughout the whole fingers workspace. It is also able to generated force feedback when necessary. Finally, I studied the control laws of this interface in all its operating phases and its performances were evaluated
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Taphouse, John Harold. "Thermal contact resistance in carbon nanotube forest interfaces." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54853.
Повний текст джерелаАнотація:
The continued miniaturization and proliferation of electronics is met with significant thermal management challenges. Decreased size, increased power densities, and diverse operating environments challenge the limitations of conventional thermal management schemes and materials. To enable the continuation of these trends thermal interface materials (TIMs) that are used to enhance heat conduction and provide stress relief between adjacent layers in a electronic package must be improved. Forests comprised of nominally vertically aligned carbon nanotubes (CNTs), having outstanding thermal and mechanical properties, are excellent candidates for next-generation thermal interface materials (TIMs). However, despite nearly a decade of research, TIMs based on vertically aligned CNT forests have yet to harness effectively the high thermal conductivity of individual CNTs. One of the key obstacles that has limited the performance of CNT TIMs is the presence of high thermal contact resistances between the CNT free ends and the surfaces comprising the interface. The aim of this research is to better understand the mechanisms by which the thermal contact resistance of CNT forest thermal interfaces can be reduced and to use this understanding towards the design of effective and to scalable processing methods. Contact area and weak bonding between the CNT tips and opposing surface are identified as factors that contribute significantly to the thermal contact resistance. Three strategies are explored that utilize these mechanisms as instruments for reducing the contact resistance; i) liquid softening, ii) bonding with surface modifiers, and iii) bonding with nanoscale polymer coatings. All three strategies are found to reduce the thermal contact resistance at the CNT forest tips to below 1 mm2-K/W, a value to where it is no longer the factor limiting heat conduction in CNT forest TIMs. These strategies are also relatively low-cost and amenable to scaling for production when compared to existing metal-based bonding strategies.
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Dubourg, Fabien. "Nanomécanique et dynamique des polymères par microscopie de force en contact intermittent." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2002. http://tel.archives-ouvertes.fr/tel-00007198.
Повний текст джерелаАнотація:
Ce mémoire présente une étude des propriétés de polymères à petite (nano) échelle, par les modes de modulation d'amplitude (« Tapping ») et de modulation de fréquence (« Non-contact » résonant) de la Microscopie à Force Atomique. Il débute par la détermination des origines physiques du contraste d'images obtenues sur une surface de copolymère tri- séquencé : la reconstruction d'une section d'image grâce aux courbes d'approche- retrait permet d'en attribuer le contraste aux seules variations de la réponse viscoélastique du copolymère (i.e. de montrer l'absence de contribution topographique au contraste). L'étape suivante est une évaluation des constantes physiques des deux nanophases du même copolymère tri- séquencé par l'analyse de courbes d'approche- retrait en mode modulation d'amplitude. Pour cela nous modélisons analytiquement et numériquement l'interaction non-linéaire et dissipative entre nano-pointe oscillante et polymère. Puis un résultat expérimental charnière montre qu'en mode modulation d'amplitude avec un facteur de qualité Q suffisamment élevé un matériau de raideur locale très faible peut apparaître dur et sa topographie être mesurée sans déformation. Cela signifie que, sur un échantillon suffisamment mou, la variation contrôlée du facteur de qualité Q permet d'accéder sélectivement aux propriétés mécaniques ou topographiques. La dernière partie concerne la dépendance d'échelle de la viscoélasticité d'un polymère fondu enchevêtré. On utilise le mode modulation de fréquence avec un facteur Q très élevé : lorsque l'indentation de la pointe dans le polymère et leur temps d'interaction atteignent des valeurs seuils, la puissance nécessaire pour maintenir une amplitude d'oscillation constante présente une augmentation abrupte. On montre que cette augmentation de la dissipation est due au passage d'une relaxation moléculaire rapide (<10-8 s, mouvement de type Rouse à faible indentation) à une relaxation beaucoup plus lente (>10-5s, désenchevêtrement lorsque la taille de l'objet indenté dépasse celle de la maille du réseau de chaînes). Cette transition correspond à une variation de profondeur d'indentation de quelques angströms.
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Dubourg, Fabien. "Nanomécanique et dynamique des polymères par microscopie de force en contact intermittent." Phd thesis, Bordeaux 1, 2002. http://www.theses.fr/2002BOR12630.
Повний текст джерелаАнотація:
Ce travail est une étude des propriétés de matériaux polymères à l'échelle du nanomètre par les modes dynamiques de modulation d'amplitude dit " Tapping " et de modulation de fréquence dit " Non-Contact Résonant" de la microscopie à force atomique. Il débute par la détermination des origines physiques du contraste d'images obtenues sur des surfaces de coplymères triséquencés. Ce contraste se révèle être dû aux variations nanométriques des propriétés viscoélastiques. L'étape suivante est une évaluation des constantes physiques des deux nanophases du copolymère triséquencé par l'analyse des courbes d'approche-retrait en modulation d'amplitude. Pour cela nous décrivons les effets sur l'oscillateur des interactions conservatives et non-conservatives entre la pointe et le polymère. Puis un résultat expérimental charnière montre qu'en mode modulation d'amplitude avec un facteur de qualité Q suffisamment élevé un matériau de raideur locale très faible peut apparaître dur pour l'oscillateur, si bien que sa structure non-déformée peut être déterminée. Ce durcissement apparent implique une réduction de l'aire de contact pointe-surface et par conséquent un Q élevé peut conduire à une amélioration de la résolution sur les matériaux mous en mode modulation d'amplitude. De plus ces résultats montrent que la variation du facteur de qualité Q permet d'accéder sélectivement aux propriétés mécaniques ou topographiques. La troisième et dernière partie est une étude de la dynamique dépendante d'échelle d'un polymère fondu enchevêtré, le polyisoprène ou caoutchouc d'Hévéa. Cette étude utilise le mode modulation de fréquence avec un facteur de qualité Q très élevé. Une transition entre deux types de mouvements moléculaires de temps de relaxation très différents est créée et détectée par l'oscillateur. La transition entre une relaxation moléculaire locale de type Rouse et une relaxation par reptation forcée amène un changement radical de l'énergie à fournir pour maintenir une amplitude d'oscillation constante de la nanopointe.
Книги з теми "Interfaces à contact intermittent"
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Portuguese-Spanish interfaces: Diachrony, synchrony, and contact. Amsterdam: John Benjamins Publishing Company, 2014.
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Rosemary, Goydan, and Risk Reduction Engineering Laboratory (U.S.), eds. A Method to measure protective clothing permeation under intermittent chemical contact conditions. Cincinnati, OH: U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, 1989.
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Rosemary, Goydan, and Risk Reduction Engineering Laboratory (U.S.), eds. A Method to measure protective clothing permeation under intermittent chemical contact conditions. Cincinnati, OH: U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, 1989.
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4
Fearn, David. Contact. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198746379.003.0003.
Повний текст джерелаАнотація:
This chapter offers a new reading of Pindar’s Nemean 8. It investigates the ways in which Pindar frames consciousness about art, cult, and the material world with the language and imagery of desire, vision, and physical contact. Discussion is built around the encounter with the Aeginetan cult hero Aiakos, and the potential for interfaces with contemporary art and ritual through contextual allusion to his Aeginetan shrine. This forms the basis for a broader treatment of the poem’s visual and haptic metaphors, and a wider-ranging musing on epinician poetry’s potential to grant special access: to the mythical; to ritual; to heroes; to the deceased and to the past; to context. These findings are then built upon to offer a fresh interpretation of the encounter with the hero Alcmaeon in Pindar’s Pythian 8.
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Drops and Bubbles in Contact with Solid Surfaces. CRC Press, 2011.
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Dynamic contact angle of a liquid spreading on a heated plate. Gaithersburg, MD: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1999.
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7
Alaric, Hall, and Kilpiö Matti, eds. Interfaces between language and culture in medieval England: A festschrift for Matti Kilpiö. Leiden [The Netherlands]: Brill, 2010.
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Alaric, Hall, and Kilpiö Matti, eds. Interfaces between language and culture in medieval England: A festschrift for Matti Kilpio. Boston: Brill, 2010.
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Extended Load/Unload/Reload Hyperbolic Model for Interfaces: Parameter Values and Model Performance for the Contact Between Concrete and Coarse Sand. Storming Media, 2000.
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10
Mate, C. Mathew, and Robert W. Carpick. Tribology on the Small Scale. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780199609802.001.0001.
Повний текст джерелаАнотація:
Friction, lubrication, adhesion, and wear are prevalent physical phenomena in everyday life and in many key technologies. The goal of this book is to incorporate a bottom up approach to friction, lubrication, and wear into a versatile textbook on tribology. This is done by focusing on how these tribological phenomena occur on the small scale—the atomic to the micrometer scale—a field often called nanotribology. The book covers the microscopic origins of the common tribological concepts: roughness, elasticity, plasticity, friction coefficients, and wear coefficients. Some macroscale concepts (like elasticity) scale down well to the micro- and atomic scale, while other macroscale concepts (like hydrodynamic lubrication) do not. In addition, this book also has chapters on topics not typically found in tribology texts: surface energy, surface forces, lubrication in confined spaces, and the atomistic origins of friction and wear. These chapters covered tribological concepts that become increasingly important at the small scale: capillary condensation, disjoining pressure, contact electrification, molecular slippage at interfaces, atomic scale stick-slip, and bond breaking. Numerous examples are provided throughout the book on how a nanoscale understanding of tribological phenomena is essential to the proper engineering of important new technologies such as MEMS, disk drives, and nanoimprinting. For the second edition, all the chapters have been revised and updated, with many new sections added to incorporate the most recent advancements in nanoscale tribology. Another important enhancement to the second edition is the addition of problem sets at the end of each chapter.
Частини книг з теми "Interfaces à contact intermittent"
1
Voigtländer, Bert. "Intermittent Contact Mode/Tapping Mode." In Atomic Force Microscopy, 231–53. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-13654-3_14.
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Voigtländer, Bert. "Intermittent Contact Mode/Tapping Mode." In Scanning Probe Microscopy, 205–21. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-45240-0_15.
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Scrosatti, B., and R. Mammone. "Interfaces and Contact Problems." In Conducting Polymers, 207–8. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3907-3_20.
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Clements, J. Clancy. "Form selection in contact languages." In Portuguese-Spanish Interfaces, 377–401. Amsterdam: John Benjamins Publishing Company, 2014. http://dx.doi.org/10.1075/ihll.1.20cle.
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Wriggers, Peter. "Constitutive Equations for Contact Interfaces." In Computational Contact Mechanics, 69–108. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/978-3-540-32609-0_5.
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Quintana, Aldina. "Judeo-Spanish in contact with Portuguese." In Portuguese-Spanish Interfaces, 65–94. Amsterdam: John Benjamins Publishing Company, 2014. http://dx.doi.org/10.1075/ihll.1.05qui.
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Carvalho, Ana Maria. "Sociolinguistic continuities in language contact situations:." In Portuguese-Spanish Interfaces, 263–94. Amsterdam: John Benjamins Publishing Company, 2014. http://dx.doi.org/10.1075/ihll.1.14car.
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Martins, Cristina. "Mirandese in contact with Portuguese and Spanish." In Portuguese-Spanish Interfaces, 295–315. Amsterdam: John Benjamins Publishing Company, 2014. http://dx.doi.org/10.1075/ihll.1.15mar.
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Storz, Matthias, and Peter Vielsack. "Numerical Sensitivity of a Dynamical System with Dry Friction and Unilateral and Intermittent Constraints." In Contact Mechanics, 427–30. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1983-6_58.
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Miyayama, Masaru, Yoshinobu Nakamura, Hiroaki Yanagida, and Kunihito Koumoto. "Chemical Sensors Using Hetero-Contact of Ceramics." In Interfaces in New Materials, 76–83. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3680-8_8.
Повний текст джерелаТези доповідей конференцій з теми "Interfaces à contact intermittent"
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Mugisha, Stanley, Matteo Zoppi, Rezia Molfino, Vamsi Guda, Christine Chevallereau, and Damien Chablat. "Safe Collaboration Between Human and Robot in a Context of Intermittent Haptique Interface." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-71518.
Повний текст джерелаАнотація:
Abstract In the list of interfaces used to make virtual reality, haptic interfaces allow users to touch a virtual world with their hands. Traditionally, the user’s hand touches the end effector of a robotic arm. When there is no contact, the robotic arm is passive; when there is contact, the arm suppresses mobility to the user’s hand in certain directions. Unfortunately, the passive mode is never completely seamless to the user. Haptic interfaces with intermittent contacts are interfaces using industrial robots that move towards the user when contact needs to be made. As the user is immersed via a virtual reality Head Mounted Display (HMD), he cannot perceive the danger of a collision when he changes his area of interest in the virtual environment. The objective of this article is to describe movement strategies for the robot to be as fast as possible on the contact zone while guaranteeing safety. This work uses the concept of predicting the position of the user through his gaze direction and the position of his dominant hand (the one touching the object). A motion generation algorithm is proposed and then applied to a UR5 robot with an HTC vive tracker system for an industrial application involving the analysis of materials in the interior of a car.
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Chuprakov, Dimitry, and Romain Prioul. "Hydraulic Fracture Height Containment by Weak Horizontal Interfaces." In SPE Hydraulic Fracturing Technology Conference. SPE, 2015. http://dx.doi.org/10.2118/spe-173337-ms.
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Abstract Weak formation bedding planes create a unique mechanism for hydraulic fracture height containment. They arrest the vertical growth of hydraulic fracture. The propagation across them may or may not occur. To quantify this fracture behavior, first we developed an analytical model of the elastic T-shaped fracture contact with frictional and cohesional interfaces. The model evaluates the fracture blunting and the shear activation of the interfaces. It predicts the buildup of the net pressure necessary for the fracture to cross the given interface. Next we conduct numerical simulations of the 3D fracture propagation in a formation with closely spaced horizontal interfaces. These simulations manifest intermittent and decelerated fracture growth in height, especially with low-viscosity fracturing fluids. This mechanism of fracture height containment is independent of the multilayer stress-contrast mechanism used conventionally. Combined with the stress mechanism, the fracture height containment model could alleviate the problem of height growth overestimation in some fracturing simulation cases.
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De La Cruz, Oscar, Florian Gosselin, Wael Bachta, and Guillaume Morel. "Contributions to the Design of a 6 DoF Contactless Sensor Intended for Intermittent Contact Haptic Interfaces." In 2018 3rd International Conference on Advanced Robotics and Mechatronics (ICARM). IEEE, 2018. http://dx.doi.org/10.1109/icarm.2018.8610825.
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Perry, Scott S., Ian Laboriante, and Xiaoping Yan. "Vapor Phase Lubrication of Gold/Gold Interfaces." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63773.
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The extension of current micro-satellite development efforts calls for a reduction in size by up to two orders of magnitude. Such a reduction in size necessitates the development of novel actuators, switches, and sensors operating on the micron length scale. The leading technology for creating such devices involves microfabrication processes currently used in the production of integrated circuits. Devices generated by these means are referred to as Micro-Electro-Mechanical Systems (MEMS). While many challenges remain in the design and production of MEMS, a critical aspect of their successful deployment involves lubrication of the devices to prevent wear and permanent, undesired adhesion (seizure) of the miniature moving parts. Results from research addressing the vapor phase lubrication of gold-gold contacts, modeling interfaces expected to be encountered in future RF MEMS devices, will be presented. Such interfaces will require high frequency intermittent contact, the absence of irreversible interfacial adhesion, the general absence of sliding within the contact, and the requirement of electrical conductivity upon contact. Work in this area has focused on the use of alklythiols as a means of controlling interfacial adhesion. Experiments have been carried out using atomic force microscopy to characterize adhesion as a function of alkylthiol chain length. In addition, these experiments have incorporated the simultaneous measurement of interfacial currents to explore load versus conductivity relationships. These measurements have been supported through measurements of surface composition through correlated quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) measurements.
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Kiely, James, and Yiao-Tee Hsia. "A Novel Method of Characterizing Slider Dynamic Motion During Intermittent Head-Disk Contact." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63195.
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Characterization of slider motion induced by contact is becoming a critical aspect of developing advanced head-disc interfaces. While vertical motion induced by contact has been studied, very little is known about down-track motion. We have introduced a new technique where the down-track motion is captured and the dynamics in three dimensions are analyzed. We have applied this technique to measure the position of a slider as it transitions from flying to making full contact with the media surface. We find that slider motion varies considerably with varying levels of interference and that motion in all three directions is considerable. Spectral decomposition is used to identify the vibration modes that are excited in each direction, and we find that for most of the test velocities, vertical modes give rise to motion in the two orthogonal directions. In addition, we present a depiction of the vertical, down-track, and off-track position changes by plotting the position of the slider in real space coordinates to help visualize more completely the slider trajectory. Analysis of motion identifies that at some levels of interference, a majority of motion is repeatable, but that non-repeatable components increase with the amount of interference. Additionally, down-track motion is the only component whose magnitude increases monotonically with increasing interference.
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Lee, Sung-Chang, and Andreas A. Polycarpou. "Predicting Fly-Height Modulation and Contact Forces in Ultra-Low Flying Head-Disk Interfaces Using a Tri-State Switching Dynamic Contact Model." In STLE/ASME 2001 International Joint Tribology Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/trib-nano2001-104.
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Abstract In order to achieve higher recording densities up to 1 Tbit/In2 using conventional recording technologies, the recording slider will need to “fly” within 5 nm or less from the rotating disk. In such ultra-low flying height regimes, intermittent head/disk contact is unavoidable. Head/disk contact can cause large vibrations of the recording slider in the normal and lateral (off-track) directions as well as damage the disk due to large dynamic contact forces. This paper describes a simple continuum mechanics-based model that includes the dynamics of a flying head/disk interface (HDI) as well as the contact dynamics. Specifically, a lumped parameter one degree-of-freedom, three state nonlinear dynamic model representing the normal dynamics of the HDI and an asperity-based contact model are developed. The effects of realistic (dynamic microwaviness) and harmonic input excitations, contact stiffness (surface roughness) and air-bearing force during contact on fly-height modulation (FHM) and contact force are investigated. Based on the tri-state model predictions, design guidelines for reduced FHM and dynamic contact force are suggested.
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Frammelsberger, Werner, Guenther Benstetter, Thomas Schweinboeck, Richard Stamp, and Janice Kiely. "Advanced Analysis of Thin and Ultrathin SiO2 Films and SiO2/Si Interfaces with Combined Atomic Force Microscopy Methods." In ISTFA 2003. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.istfa2003p0406.
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Abstract In this work a procedure is presented to look beneath the surface of a SiO2 film and to study the impact of the SiO2/Si interface morphology on the tunneling current, with high lateral resolution, by use of combined Conductive Atomic Force Microscopy (C-AFM) and Intermittent-Contact AFM (IC-AFM) measurements. Evidence is given that interface structures do have direct influence on the distribution of high current spots in MOS capacitors.
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Li, Dongwu, and Chao Xu. "Modelling of Mechanical Systems With Friction Interfaces Considering Variable Normal Contact Load and Tangential Micro/Macro Slip." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65995.
Повний текст джерелаАнотація:
Mechanical structures with frictionally constrained interfaces often involve complex contact kinematics induced by tangential and normal relative motions. The tangential motion induces stick-micro/macro slip friction and causes energy dissipation. The normal motion induces normal load variation and possible separation of the joint interfaces. For effective analysis of dynamics of jointed structures, a reduced friction contact model is needed to characterize the nonlinear, coupled normal and tangential contact behaviors precisely. However, most developed microslip friction contact models considers only constant normal load. In this paper, an improved microslip friction model with normal load variation induced by normal motion is proposed. The tangential stick-micro/macro slip friction is modeled by continuous Iwan hysteretic model. This model is characterized by a slippage uniform distribution density function and a linear stiffness at stick state. The coupling relationship between tangential nonlinear restoring force and normal load variation is built. This leads to generalization of the original Iwan hysteretic friction model to consider the effect of variable normal load. The proposed model is applied to model a 7-dofs frictional damping experimental system. The results show that normal load variation and tangential microslip motion exert an important effect on prediction of friction contact behaviors. The proposed model is capable of generating asymmetric hysteresis loops and intermittent normal separation. The numerical simulation fit well with the experimental results for the 7-dofs frictional damping system, which validates the effectiveness and accuracy of the proposed model.
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Petrov, E. P. "Multiharmonic Analysis of Nonlinear Whole Engine Dynamics With Bladed Disc-Casing Rubbing Contacts." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68474.
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A method has been developed for frequency domain analysis of steady state forced response in gas turbine engines in the presence of rubbing and snubbing contacts between bladed discs and casing and between other rotor and stator engine components. The multiharmonic contact interface elements have been derived for modelling the nonlinear contact interactions: (i) at bearings and (ii) bladed disc-casing rubbing contacts with using flexible models for rotor and stator structures. The elements allow for the asymmetry of the casing, the discrete blade contacts with casing, individual blade-casing gap values, nonlinear dependency of the contact forces on rotor-stator incursion and friction forces, intermittent contacts between blades and the casing. High accuracy and computational efficiency of the methods and models developed has been demonstrated on a set of test cases and on an example of analysis of a realistic gas turbine structure.
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Peng, Wei, James Kiely, and Yiao-Tee Hsia. "Wear Analysis of Head-Disk Interface During Contact." In ASME/STLE 2004 International Joint Tribology Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/trib2004-64050.
Повний текст джерелаАнотація:
To achieve a higher storage density in a hard disk drive, the fly height of the air bearing slider, as part of the magnetic spacing, has to be minimized. At an ultra-low fly height, the intermittent / continuous contact at the head–disk interface (HDI) is unavoidable and directly affects the mechanical and magnetic performance of the hard disk drive, and is of great interest. The HDI wear has a non-linear and time-varying nature due to the change of contact force and roughness. To predict the HDI wear evolution, an iterative model of Coupled Head And Disk (CHAD) wear, is developed based on the contact mechanics. In this model, a composite transient wear coefficient is adopted and multiple phases of the wear evolution are established. A comprehensive contact stiffness is derived to characterize the contact at the HDI. The abrasive and adhesive wear is calculated based on the extended Archard’s wear law. The plastic and elastic contact areas are calculated with a 3-D sliding contact model. Based on the CHAD wear model, for the first time, the coupling between head and disk wear evolutions is thoroughly investigated. Accelerated wear tests have also been performed to verify the disk wear effect on the slider wear. A wear coefficient drop with time is observed during the tests and it is attributed to a wear mechanism shift from abrasive to adhesive wear. A shift in the type of contact from plastic to elastic accounts for the wear mechanism change.
Звіти організацій з теми "Interfaces à contact intermittent"
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Blum, L. Contact Theorems for Rough Interfaces. Fort Belvoir, VA: Defense Technical Information Center, April 1994. http://dx.doi.org/10.21236/ada282988.
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Gomez, Jesus E., George M. Filz, and Robert M. Ebeling. Extended Load/Unload/Reload Hyperbolic Model for Interfaces: Parameter Values and Model Performance for the Contact Between Concrete and Coarse Sand. Fort Belvoir, VA: Defense Technical Information Center, December 2000. http://dx.doi.org/10.21236/ada392683.
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