Gotowa bibliografia na temat „Lubricant conditions”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Zobacz listy aktualnych artykułów, książek, rozpraw, streszczeń i innych źródeł naukowych na temat „Lubricant conditions”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Artykuły w czasopismach na temat "Lubricant conditions"
1
A. Shalwan, Talal Alajmi i Naser Alajmi. "Study on the tribological performance of bio-lubricant conditions- Review". Global Journal of Engineering and Technology Advances 16, nr 2 (30.08.2023): 001–11. http://dx.doi.org/10.30574/gjeta.2023.16.2.0125.
Pełny tekst źródłaStreszczenie:
The products based on fossil oils are increasing with the concerns of the environmental sectors and academics as well. In this era, there are challenges to finding alternative resources replacing fossil oil for different engineering applications. One of the fossil oil products is lubricant. Fossil lubricants have many industrial applications and involve millions of dollars each year in the development of lubricants due to their huge needs. Accordingly and to satisfy the industrial needs with the environmental considerations, alternative environmentally-friendly-Lubricants are nowadays the main aim identity by the tribologists. The main objective of this work is to investigate the usage of vegetarian oils as lubricant. For that , many bio-lubricants based on vegetable oil were studied and investigated the influence of these oils on wear and frictional characteristics of adhesive wear. Also, the results are very encouraging to candy the bio-lubricant as an alternative to synthetic oils any many industrial applications.
2
Surakasi, Raviteja, Ravi Ganivada i Ramya Pakalapati. "Study Comparing the Tribological Behavior of Cottonseed and Castor Oil Biodiesel Blended Lubricant under varying Load Conditions". International Journal for Research in Applied Science and Engineering Technology 11, nr 4 (30.04.2023): 4047–55. http://dx.doi.org/10.22214/ijraset.2023.51178.
Pełny tekst źródłaStreszczenie:
Abstract: We have an increasing global need for bio lubricants that are safe for human and environmental use, easily biodegradable, and non-polluting. The friction and wear qualities of cotton seed blended lubricant as well as castor blended lubricant are compared and contrasted in this research using a Pin on disc wear testing Tribometer. In this research, we will look at the study's results and analyse their significance. Blended lubricants were created by combining cotton seed & castor based biodiesel with the basic lubricant SAE20W40 at volumetric ratios of 5, 10, 15, & 20%. Cotton seed and castor blended bio lubricants were tested for friction and wear at sliding velocities of 2.5 metres per second while subjected to weights of 50 N, 100 N, and 150 N. Wear might be slowed by as much as 15 percent by mixing in cotton seed biodiesel with the base oil, as has been shown. When this threshold is passed, wear increases at an ever-increasing pace. Castor oil blended lubricant performed best in wear tests when coupled with a base lubricant at a 5 and 10 percent castor oil blended lubricant concentration. The wear rate was accelerated when 15 percent castor oil was added to the basic lubricant. It has been discovered that at lowest and maximum load, CBL 5 and CBL 10 may serve as an alternative lubricant to increase mechanical efficiency at a sliding velocity of 2.5 metres per second. Because of their efforts, less need has been seen to lessen dependence on petroleum-based goods.
3
Djordjević, Milan, Vesna Mandić, Srbislav Aleksandrović, Vukić Lazić, Dušan Arsić, Ružica R. Nikolić i Zvonko Gulišija. "Experimental-numerical analysis of contact conditions influence on the ironing strip drawing process". Industrial Lubrication and Tribology 69, nr 4 (10.07.2017): 464–70. http://dx.doi.org/10.1108/ilt-05-2016-0113.
Pełny tekst źródłaStreszczenie:
Purpose The purpose of this paper is comparison of experimental values of the drawing forces to numerical values in different contact conditions, taking into account the appearance of galling which occurs due to of difficult drawing process conditions. Design/methodology/approach The following two research approaches are used in this paper – the physical modeling, realized by the laboratory experiment, and the numerical simulation of the ironing drawing process. By analyzing the obtained results, the technique of physical modeling, with help of the laboratory equipment and numerical simulation by application of the finite element method, can be successfully used in studying the thin sheet ironing – strip drawing process. Findings It is significant to compare values of the deformation forces obtained by physical experiment to values obtained by the numerical simulation. In that way, it is possible to compare applied contact conditions (four lubricants in that case) and estimate matching of experimentally and numerically obtained results of the deformation forces. Presented results point out very good technological characteristics of ecologically friendly lubricant (single-bath) and grease based on MoS2. Significant decrease of the deformation force was achieved by its application, as well as maintaining of the lubricant’s layer during the forming process and almost complete elimination of galling on the contact. Practical implications Numerical analysis of stresses in the working piece wall, during the thin sheet strip drawing, requires precise values of the friction coefficient. It is an important indicator because one can define the contact conditions as the input data for the numerical simulation, based on its values for each type of lubricants and each value of the compressive lateral force. Originality/value The environmentally friendly lubricant tested exhibits a more favorable distribution of the drawing force during the process, mainly in experimental case. Grease based on MoS2 has good lubricating properties but that lubricant is conventional and environmentally unacceptable. Ecologically friendly lubricant can be successfully used in real ironing strip drawing process especially for high values of holding force achieving an increased tool life.
4
Streator, J. L., B. Bhushan i D. B. Bogy. "Lubricant Performance in Magnetic Thin Film Disks With Carbon Overcoat—Part I: Dynamic and Static Friction". Journal of Tribology 113, nr 1 (1.01.1991): 22–31. http://dx.doi.org/10.1115/1.2920599.
Pełny tekst źródłaStreszczenie:
Static and dynamic friction coefficients are presented for an Al2O3·TiC slider in contact with 130 mm carbon-coated rigid thin film disks lubricated with several different perfluoropolyether lubricants. The lubricants tested include three nonpolar liquid lubricants and one polar liquid lubricant with dihydroxyl end groups. The effects of lubricant film thickness, disk surface topography, sliding speed and lubricant viscosity are investigated. In many cases, the interfaces exhibited a sharp increase in the dynamic and static friction coefficients after a certain film thickness was reached, due to strong adhesion in the interface. In most cases, the lubricant thickness for the onset of high friction forces was found to increase with increasing disk surface roughness, lubricant viscosity and sliding speed. Under certain conditions stick/slip of the slider occurred during which the static friction increased with time of contact. The various data suggest that the rate at which strong adhesion develops depends on the lubricant viscosity.
5
Glazunov, D. V. "Development of the lubricant for side-mounted rail flange lubricators for traction rolling stock". Vestnik of the Railway Research Institute 78, nr 1 (13.05.2019): 59–64. http://dx.doi.org/10.21780/2223-9731-2019-78-1-59-64.
Pełny tekst źródłaStreszczenie:
Specificity of operating conditions of the rolling stock defines a number of requirements for lubricants intended for the wheel-rail tribosystem. Lubricants are used for “wheel — rail” contact, the aggregate state of which varies from liquid to solid. When evaluating the lubrication properties of these materials, a significant number of factors must be taken into account, in particular, influence of the environment, method of application, condition of the rail surface. The paper discusses the main operational requirements for lubricants operating in a wheel-rail tribosystem. Temperature ranges of the lubricants used for the “wheel — rail” contact on the railway network of the Russian Federation are given. As a result of the research, it was determined that none of the materials used for lubrication of the wheel-rail system satisfies the operating temperature conditions of the traction rolling stock. To solve this problem a lubricant was developed and tested in an industrial environment at the Rostov State University of Railway Transport. Its lubricant composition allows to significantly expand the temperature range of the lubricant. Complex of experimental studies and method of orthogonal central composite plan of the 2nd order established the optimum values of the thickness of the working shell of the 0.846 mm lubricating rod and the 50.411 % percentage of plastic lubricant, allowing to extend the temperature range of lubricant rods and, in particular, completely eliminate the lubricant flow to achieve a temperature of 126.034 °C. Proposed composition of the lubricant was tested on a freight electric locomotive of the VL80T series, equipped with non-power lubricators, under the conditions of the Bataysk — Likhaya section of the North Caucasus Railway. Intensity of wear of the wheel flanges of the traction rolling stock lubricated by the proposed material, compared with the intensity of wear of the wheel flanges without the use of lubrication systems is reduced by 2 times.
6
Rodríguez Leal, Bárbara, Justine Decrozant-Triquenaux, Jens Hardell i Leonardo Pelcastre. "Development of a Laboratory-Scale Test Methodology for Performance Evaluation of Lubricants for Hot Stamping of an Aluminium Alloy". Lubricants 11, nr 9 (23.08.2023): 359. http://dx.doi.org/10.3390/lubricants11090359.
Pełny tekst źródłaStreszczenie:
In hot stamping of aluminium, the need for efficient methods to evaluate, compare, and rank lubricants based on their tribological performance is critical in the early stages of selection. Pilot and simulative testing can be costly, time-consuming, and complex, making it inefficient for initial benchmarking. This work aims to develop a test methodology to assess lubricant performance for hot stamping under key operating conditions without fully simulating the forming process. The proposed method distinguishes the impact of temperature on lubricant degradation, friction, wear response, and cleanability. The tests utilised a conventional hot work tool steel and a 6010S aluminium alloy with two commercially available lubricants: a polymeric lubricant and a lubricant containing graphite. The tribological tests involved a reciprocating, sliding flat-on-flat configuration at two temperatures (100 °C and 300 °C). The methodology showed that the graphite-containing lubricant exhibited over a four times lower friction coefficient than the polymer-based lubricant at 10 wt.% concentration and 300 °C. At 100 °C, both lubricants provide lubrication and can be cleaned, but increasing temperature led to a significant decline of both aspects. The observed temperature range where the lubricants degrade was between 120 °C and 170 °C.
7
Bak, Mun-Gyu, Jong-Sung Won, Seon-Woong Koo, Arom Oh, Han-Ki Lee, Dae-Sik Kim i Seung-Goo Lee. "Migration Behavior of Lubricants in Polypropylene Composites under Accelerated Thermal Aging". Polymers 13, nr 11 (25.05.2021): 1723. http://dx.doi.org/10.3390/polym13111723.
Pełny tekst źródłaStreszczenie:
The surface migration of lubricants degrades the quality of thermoplastic polymer composites. In this study, the surface migration of lubricants in polypropylene composites were studied to improve the quality of the composites. Polypropylene (PP)/lubricant composites were manufactured using a co-rotating twin-screw extruder and injection molding, and the migration phenomena of the lubricant in the PP/lubricant composites were investigated under accelerated aging conditions with temperatures in the range of 20 to 90 °C and humidity of 100% for 72 h. The interrelation between the surface migration properties of PP/lubricant composites were investigated by considering their microstructural and morphological features, which were influenced by the thermal aging conditions. Further, the microstructural and morphological features were examined by contact angle, surface energy, attenuated total reflectance Fourier-transform infrared spectrometry, X-ray photoelectron spectroscopy, close-up digital imaging, and atomic force microscopy analyses. The polypropylene composites containing the magnesium stearate as the lubricant were found to exhibit a more stable migration behavior than the polypropylene composites containing a calcium stearate lubricant. This is attributed to multiple synergistic factors, such as interfacial tension and work of adhesion between PP and the lubricant. The findings of this study can be utilized to effectively manufacture high-quality thermoplastic composites for the fourth industrial revolution.
8
Devlin, Mark. "Common Properties of Lubricants that Affect Vehicle Fuel Efficiency: A North American Historical Perspective". Lubricants 6, nr 3 (3.08.2018): 68. http://dx.doi.org/10.3390/lubricants6030068.
Pełny tekst źródłaStreszczenie:
The development of advanced lubricants to improve vehicle fuel efficiency can appear to be as simple as lowering the viscosity and frictional properties of a fluid. However, applied research studies have shown that it is quite difficult to quantify the fuel efficiency properties of advanced lubricants in vehicles. A review of the historical research predominantly performed in North America in this area reveals that there are many factors to consider in order to demonstrate the effectiveness of advanced lubricants. First, the methodology used to measure vehicle fuel efficiency will impact the results since there are many factors not related to the lubricant which will influence vehicle fuel efficiency. Second, developing advanced fuel-efficient lubricants under well controlled conditions overlooks the issue that lubricant properties such as viscosity and friction affect the operating conditions encountered by the lubricant in the vehicle. Finally, the physical properties of lubricants that historically control fuel economy do not have the same effect on fuel efficiency in all vehicles. The proper vehicle or system level test needs to be selected to properly assess the benefits of new advanced lubricants.
9
Jung, Yeonjin, i Changdong Yeo. "Mechano-Chemical Properties and Tribological Performance of Thin Perfluoropolyether (PFPE) Lubricant Film under Environmental Contaminants". Lubricants 11, nr 7 (21.07.2023): 306. http://dx.doi.org/10.3390/lubricants11070306.
Pełny tekst źródłaStreszczenie:
Through molecular dynamics (MD) simulations with ReaxFF potential, the effects of chemical contaminants on the mechano-chemical properties and tribological performance of perfluoropolyether (PFPE) lubricants were investigated. For the two types of contaminants, i.e., silicon dioxide (SiO2) nanoparticles and water (H2O), their molecular interactions with the two different PFPE lubricants, i.e., Ztetraol and ZTMD, were evaluated at the two different temperatures, i.e., 300 K and 700 K. Contaminants were adsorbed onto the PFPE lubricants at a controlled temperature. Then, air shear simulations were conducted to examine the mechano-chemical behaviors of the contaminated lubricants. Sliding contact simulations were performed to further investigate the tribological performance of the contaminated lubricants, from which the resulting friction and surface contamination were quantified. Lastly, chemical reactions between PFPE lubricants and contaminants were studied to investigate the degradation of PFPE lubricants. It was observed that SiO2 nanoparticles stiffened the PFPE lubricant, which decreased its shear displacement and increased friction. In the case of the H2O contaminant, it weakened and decreased the PFPE lubricant’s viscosity, increasing its shear displacement and lowering friction. However, the decreased viscosity by H2O contaminants can weaken the lubricity of the PFPE lubricant, leading to a higher chance of direct solid-to-solid contact under high contact force conditions.
10
Chandran Suja, Vineeth. "Challenges in Mitigating Lubricant Foaming". Lubricants 10, nr 6 (1.06.2022): 108. http://dx.doi.org/10.3390/lubricants10060108.
Pełny tekst źródłaStreszczenie:
Lubricant foaming and its mitigation is an active area of research driven by demands from modern machinery that require foam-free lubricant operation over extended periods and under adverse conditions. Tackling lubricant foaming has proven to be challenging due to interdependent foam stabilization mechanisms and a multitude of antifoam inactivation routes. This perspective briefly outlines the key challenges faced by researchers in this field. Overcoming these challenges to create lubricants with superior foaming characteristics requires the development of new lubricant and antifoam chemistry as well as a shift from the existing trial-and-error methods to mechanistic-insight-driven lubricant formulation and antifoam design.
Rozprawy doktorskie na temat "Lubricant conditions"
1
Tracy, Ian Patrick. "Enhanced engine mechanical efficiency through tailoring of lubricant formulations to localized power cylinder wall conditions". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98583.
Pełny tekst źródłaStreszczenie:
Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2015.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 74-75).
Numerical and experimental studies were performed on an internal combustion engine power cylinder wall's lubricating oil film in order to assess the possibility of tailoring engine lubricants to specific engine configurations and operating conditions for significantly enhanced fuel economy without an accompanying increase in engine wear. An array of different base oil viscosity modifier type combinations were developed, tested, and analyzed in order to seek trends that link lubricant mixtures to certain rheological behaviors along the cylinder wall of a fired internal combustion engine. Viscosity modifiers were applied in an unconventional manner so as to increase viscosity at high operating temperatures rather than decreasing viscosity at low temperatures for promoting reliable cold-cranking. Consequently, a novel form of multi-grade lubricant was developed and simulated for determining potential fuel economy gains through its use. Both numerical simulation and a physical, laser-induced fluorescence diagnostic apparatus for an Isuzu 4JJ1 light-duty diesel engine were implemented in parallel to aid the development and validation of a reliable engine friction and wear model. Preliminary results have been insightful and coincident with classical continuum mechanics theory. Internal consistency across the developed model and physical diagnostics was considerable. It is concluded that the tailoring of lubricant formulations can realize substantial fuel economy gains, and that oil & gas companies may realize significant competitive advantage and profit should they successfully inspire customers to consider purchasing lubricants that have been designed specifically for their automobile and driving habits. It is further proposed that the standards associated with lubricant classification be improved so as to consider the use of viscosity modifiers as mitigators of engine power cylinder wear at high cylinder temperatures near top dead center (TDC).
by Ian P. Tracy.
S.M. in Technology and Policy
S.M.
2
Sochting, Sven. "The effects of operating conditions on the hydrodynamic lubricant film thickness at the piston-ring/cylinder liner interface of a firing diesel engine". Thesis, University of Central Lancashire, 2009. http://clok.uclan.ac.uk/21027/.
Pełny tekst źródłaStreszczenie:
Conventional investigations into the performance of piston-rings in internal combustion engines are performed at relatively low speeds and consider only steady state operation conditions. Loss of power in internal combustion (IC) engines is becoming an increasing issue when they are operated at high engine speeds. This project is directed at developing technology to establish whether this phenomenon is influenced by a lubricant related effect. In a normal operating environment automotive engines typically operate under transient operating conditions. These rapid changes in operation conditions may influence the thickness of the hydrodynamic film which lubricates the interfaces between the piston-ring and liner. During this project two capacitance methods were employed in a fired compression ignition engine, an amplitude modulated (AM) system originally developed by Grice and a new "high speed" capacitance technique based on a frequency modulated principle. The first part of this thesis is concerned with the development and implementation of a new apparatus suitable for measuring the thickness and extent of the hydrodynamic oil film which lubricates the piston-rings and liner. The nature of the working principle of the high speed capacitance measurement system required the design, manufacture, assembly and commissioning of a novel dynamic calibration apparatus. The new system can also be used for static calibration (AM system) of capacitance based distance measuring systems. It uses a manufacturer calibrated closed loop controlled piezo-actuator to present a target relative to the sensor face. Some previous investigations concluded a stable oil film thickness. However, this work shows that there are cyclic variations of the oil film thickness OFT on a stroke to stroke and cycle to cycle basis. A series of measurements was conducted under various fixed speed load points. The effects of using lubricants of different viscosity on the minimum (OFT) between liner and piston ring have been little studied and this work shows that it was possible to speciate measurements of different lubricants. This thesis also describes a measurement of the oil film thickness during abrupt changes in engine operating conditions.
3
Serebriakov, Ivan. "Tribologie à haute température : analyse expérimentale et numérique du comportement interfacial tenant compte de l'influence des conditions de contact thermomécaniques". Thesis, Valenciennes, Université Polytechnique Hauts-de-France, 2021. http://www.theses.fr/2021UPHF0009.
Pełny tekst źródłaStreszczenie:
Dans la mise en forme à chaud des composants en acier, les conditions de frottement àl'interface pièce/outil sont sévères en particulier à cause des niveaux de températures (850°C-1250 ℃) et des charges appliquées dans ces opérations. Dans ces conditions de mise en forme,en plus du film lubrifiant, une couche d’oxyde se crée à l’interface pièce/outil qui va perturberles conditions de contact. Les objectifs de cette thèse sont non seulement d'analyser l’impacttribologique de la couche d’oxyde sur le procédé de forgeage à chaud, mais aussi d’observerl’interaction oxyde/lubrifiant. Dans le cadre du laboratoire commun SWITLab entre la sociétéMG-Valdunes, le LAMcube et le LAMIH UMR CNRS 8201, la mise en forme d’une roueferroviaire à grande vitesse a été choisie comme application.Les effets rhéologiques de la couche d'oxyde et du film lubrifiant sur l'acier ont étépréalablement estimés au moyen d'essais de compression à chaud à partir de cylindres degéométries standards et de cylindres de géométries Rastegaev. Des essais complémentaires decompression axisymétriques et de traction ont été réalisés afin de déterminer le comportementmécanique de l'outil à des températures relativement basses.Une analyse originale multi-échelle du contact pièce/outil à haute température a ensuiteété développée. Les principaux paramètres de contact ont été extraits, à macro-échelle, parobservation du procédé industriel et par une première modélisation numérique de la mise enforme. Des essais de compression-translation, ainsi que des tests roll-on-disc ont ensuite étéréalisés à méso et micro-échelle, basés sur les conditions de contact déterminées à macroéchelle.Les essais de compression-translation ont montré la présence à la fois d’oxydes écraséset incrustés sur la surface des échantillons testés. Au niveau micro-échelle, le phénomène deStick-Slip qui se produit en raison de l'accumulation des oxydes écrasés, transforment lesconditions de contact d'une configuration lubrifiant/oxyde en une condition oxyde/oxyde.Enfin, une simulation par éléments finis du procédé de forgeage à chaud de la roueferroviaire, prenant en compte les caractéristiques thermiques de la couche d'oxyde, lecoefficient de frottement déterminé à échelle méso et le comportement du matériau de l'outil, aété développée. Ce modèle permet de prédire correctement les efforts de forgeage et leremplissage des outilsIn hot-working of steel components, friction conditions at the tool/workpiece interfaceare severe due to the relatively high temperatures (850°C-1250℃) and loads involved in theseoperations. Under these processing conditions, the tool/workpiece interface usually involvesthe presence of an oxide layer and a lubricant film. The objective of this research is to analyzethe tribological effect of the oxide layer and its interaction with the lubricant used. As part ofthe joint SWITLab laboratory bringing together the industrial group MG Valdunes, theLAMcube of Lille and the LAMIH UMR CNRS 8201, the hot forging process of a railwaywheel for high-speed trains was chosen for the analysis.The rheological effect of the oxide layer and lubricant film on the steel were previouslyanalyzed by means of hot compression tests with standard cylinders and cylinders with aRastegaev design. Additionally, axisymmetric compression and tensile tests were carried out inorder to characterize the mechanical behavior of the tool material at relatively low temperatures.An original multi-scale analysis of the billet/tool contact conditions at high temperaturewas then developed. At macro-scale, the main contact parameters were extracted by means ofthe industrial forging process observations and its FE modeling. Then, upsetting-sliding testsas well as roll-on-disc tests were conducted based on the macro-scale contact conditions. Afterthe upsetting sliding both crushed and embedded oxides were found to be present on the crosssection of the tested samples. At the micro-scale level, the stick-slip phenomenon occurs due toaccumulation of the crushed oxides, which transform the interfacial contact conditions from alubricant/oxide configuration to an oxide/oxide condition.Finally, a FE model of the railway wheel hot forging process, taking into account thethermal characteristics of the oxide layer, the coefficient of friction determined at meso-scaleand the behavior of the tool material, has been developed. This model can correctly predict theforging forces and the filling of tools
4
Frýza, Josef. "Elastohydrodynamic Film Study under Impact Loading and Lateral Vibrations". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-371778.
Pełny tekst źródłaStreszczenie:
Disertační práce se zabývá chováním a odezvou elastohydrodynamického (EHD) mazacího filmu za neustálených provozních podmínek. V úvodní části práce jsou shrnuty poznatky z oblasti EHD mazání; od jeho historie, přes základní mechanismy mazání a používané experimentální metody, až po nedávno publikované studie zaměřené na transientní podmínky. Hlavním cílem práce bylo experimentálně objasnit vliv provozních parametrů a reologických vlastností maziv na chování mazacího filmu v bodovém kontaktu při jeho nárazovém zatěžování a vystavení příčným vibracím. Za tímto účelem byla vyvinuta laboratorní zařízení umožňující měření rozložení mazacího filmu a tření za kontrolovaných nestacionárních podmínek. Experimenty odhalili zásadní roli přibližovacích a zatěžovacích rychlostí na formování stlačených mazacích filmů při nárazovém zatěžování. Výsledky byly srovnávány s nedávným teoretickým řešením. Bylo ukázáno na jeho nedostatky, jež byly následně odstraněny implementací empirických vztahů zohledňujících reologii maziv. V případě příčných vibrací byly nalezeny hranice selhání mazacího filmu a určeny vztahy popisující vliv příčných vibrací na centrální tloušťku filmu a její fluktuace jednotně pro všechny maziva. Závěrečná část práce poskytuje nový pohled na reologii maziv pomocí inovativního přístupu měření třecích reakcí maziva současně ve dvou směrech kontaktu za podmínek příčných vibrací. Tyto původní výsledky rozšiřují pochopení mechanizmů EHD mazání a mohou být použity k dokonalejším návrhům strojů, a vylepšit tak jejich účinnost, spolehlivost a životnost.
5
Booth, James Edward. "The feasibility of using electrostatic charge condition monitoring for lubricant additive screening". Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/64859/.
Pełny tekst źródłaStreszczenie:
International standards require lubricant formulators to develop additive packages that increase fuel economy, reduce environmental impact and minimise wear over ever increasing service intervals. However, additive behaviour and interactions between additives is not well understood. An absence of real-time technology has hindered understanding of additive behaviour and interaction between additives in tribo-contacts. The work presented in this thesis assessed whether electrostatic charge monitoring, which is sensitive to changes in surface chemistry, can offer insight into additive-surface behaviour and how this affects tribological performance. Electrostatic sensors were deployed on tribological test apparatus used to simulate: engine valve-train, manual transmission synchroniser and automatic transmission clutch tribo-contacts. Additive performance in these simulated contacts was assessed by electrostatic surface charge measurements and cross-correlated with friction, wear and off-line surface chemistry analysis. The first study involved electrostatic monitoring of valve-train contacts, which was a continuation of previous electrostatic monitoring work carried out to relate wear and electrostatic charge. During a simulated TU3 cam-follower wear test, charge signals underwent a sign inversion; this was due to a transition between tribocharging of the lubricant under running-in and mild wear, and contact potential difference generated at the onset and progression of adhesive wear. It was found that charge signals differed between different oils, which could not be explained by the wear performance alone; this indicated that lubricant chemistry significantly affected charge generation. Dynamic charge peaks produced by simulated valve-train contacts lubricated with zinc dialkyldithiophosphate (ZnDTP) additive were related to the stripping of the tribofilm. The source of this charge peak was an increase in negative charge, which correlated with a dominance of phosphate and sulphate (anions) compared to zinc (cations), as the film was worn away. When friction modifier (FM) and dispersant additives were combined to lubricate a simulated wet clutch contact, x-ray photo-electron spectroscopy (XPS) analysis and friction data indicated that the dispersant dominated the tribofilm composition; evidenced by nitrogen levels and friction levels similar to the dispersant alone. Electrostatic charge data showed that competition for surface sites is an extremely dynamic process; as indicated by charge levels which alternated between the levels of the FM and dispersant alone. When a potassium borate additive was added to a polysulphide additive containing oil during testing (seeding), the charge data showed a transition from being predominantly positive to predominantly negative. This correlated with the formation of a borate rich (anions) layer on top of the sulphur film. Further novel tribological discoveries were found through investigation into these additive-surface charge behaviours. An underdeveloped ZnDTP tribofilm, which predominantly contained sulphur, was formed at room temperature; the sulphur promoted tribochemical wear and resulted in a pro-wear affect for primary ZnDTP. The combination of FM and dispersant showed a clear antagonism resulting in increased wear compared to the individual additives. XPS of brass and steel simulated synchroniser contacts lubricated with potassium borate and polysulphide identified the affect of surface chemistry on film formation. For the potassium borate additive: potassium (cation) preferentially adsorbed to brass, and borate (anion) preferentially adsorbed to steel. Seeding the borate additive into the oil, and therefore the contact, produced the same film composition and structure as the combination from the start. This inferred that the polysulphide additive drove initial film formation. Seeding is an extremely powerful technique, but its use is almost absent in the literature. It has been shown that lubricant chemistry dominates charge levels even in a wearing contact. Electrostatic monitoring is sensitive to the type of additive-surface adsorption and interaction between additive and additive or contaminant. Also, cross-correlation of surface charge and tribofilm chemical composition demonstrated that electrostatic sensors have the ability to detect tribofilm kinematics. This is a significant finding; no current real-time technique used to monitor tribofilm kinematics derives its measurements from the tribofilm composition. Although interpretation of electrostatic charge data is currently an intensive process, in the long term, lubricant development could see a move towards charge informed formulation.
6
Doig, Michael. "Molecular dynamics simulations of surface-active molecules under dynamic conditions found in engines". Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/17968.
Pełny tekst źródłaStreszczenie:
Lubricants oils play an important role in a wide range of industrial and mechanical processes, where they are used to reduce both the friction and wear between interacting moving surfaces. The current understanding of lubrication is mainly based on empirical evidence, obtained from experiment. In this work, computer simulations are used to gain insight into the microscopic processes that lead to the modification of friction and wear by additive molecules adsorbed on sheared surfaces lubricated by thin liquid films. The specific area of application under consideration is the lubrication of automotive engine parts. The interactions between additive molecules are first determined using density-functional theory calculations. The interactions are then validated against available experimental data, and incorporated in to large-scale molecular-dynamics (MD) simulations, which are used to explore the structure and frictional properties of lubricated surfaces. The surfaces considered are alumina and iron oxide. The lubricating oils are squalane and hexadecane, which are representative of automotive lubricants, and the additive molecules are stearic acid, oleic acid and various oleamides. MD simulations are performed over wide ranges of the relevant physical conditions, namely pressure, temperature, and shear rate. The additives adsorb on to the surfaces and provide a physical connection between the surfaces and the lubricating liquid. The structures of adsorbed films are analysed in microscopic detail using functions of atomic positions and molecular geometry. Several important trends are identified, linking molecular isomerism and architecture with the structure and stability of the adsorbed film. In addition, the simulation results are used to gain insight on recent experimental measurements of film structure. The friction coefficients in various situations are computed and analysed with reference to the structures of the adsorbed films. The synthesis of these data and observed trends yields new insights on the intimate link between the molecular properties of lubricants, and the macroscopic frictional properties of macroscopic lubricated engine parts.
7
Starbuck, J. M. "Tribological evaluation of dual lubricant condition-bearing materials for use in low pressure aerospace fuel pump systems". Thesis, University of Portsmouth, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271449.
Pełny tekst źródła
8
Meziane, Bilel. "Film thickness build-up in highly loaded lubricated contacts under Zero Entrainment Velocity condition". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI005.
Pełny tekst źródłaStreszczenie:
Les contacts lubrifiés sous forte charge sont souvent étudiés dans des conditions de roulement/glissement. Dans ces cas, l’entrainement du lubrifiant dans un coin d’huile explique la présence d’un film séparateur. Cependant, il existe un certain nombre d’applications dans lesquelles les surfaces en contact ont des vitesses égales et opposées. Cela correspond à une vitesse d’entrainement (définie comme la moyenne des vitesses des deux surfaces) nulle. Dans ce cas, les modèles prédictifs de la littérature ne peuvent plus s’appliquer. Dans ce mémoire de thèse, les phénomènes physiques conduisant à une génération de film séparateur à vitesse d’entrainement nulle sont étudiés. Un modèle éléments finis prenant en compte les aspects thermiques et transitoires est mis en œuvre pour mesurer les quantités locales. En régime stationnaire, les résultats numériques sont comparés avec un très bon accord à un jeu de données issu d’une campagne d’expérimentations dédiée. Cette approche duale permet de quantifier l’influence de la charge, de la vitesse des surfaces et de la température externe sur l’épaisseur de film à vitesse d’entrainement nulle. Les contacts sont ensuite étudiés sous une charge variable, ce qui montre l’influence relative des phénomènes thermiques et transitoires pouvant générer une épaisseur de film. En fonction du ratio entre le temps caractéristique de chargement et le temps caractéristique d’échauffement, ces effets peuvent montrer une synergie bénéfique pour le contactHighly loaded lubricated contacts are often studied in rolling/sliding conditions. In those cases, the entrainment of lubricant in a so-called “oil wedge” explains the existence of a separating film thickness. However, in a number of industrial applications, the contact is subjected to opposite surface velocities. In such cases, there is a Zero Entrainment Velocity (defined as the average velocity of the two surfaces) of the fluid. The film thickness prediction formulae developed in the literature for rolling contacts are unusable. In this thesis, the physical phenomena leading to a film build-up under Zero Entrainment Velocity condition are elucidated. A finite element model is used in order to facilitate in-situ measurements. It aims to describe the behaviour of the contact in thermal and transient conditions. In the stationary regime, the numerical values are compared with a very good agreement to a set of results obtained via a tailored experimental campaign. This dual approach enables a quantitative description of the influence of the contact load, surface velocities and external temperature on the film thickness under ZEV condition. Then, the relative influence of the thermal and squeeze effects is studied. Depending on the ratio between the characteristic loading time and the characteristic thermal time, these two effects can show a beneficial synergy for the contact
9
Sgotti, Carlos Eduardo. "Investigação do comportamento de defeitos em engrenagens cilíndricas de dentes retos utilizando monitoramento da condição". Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153802.
Pełny tekst źródłaStreszczenie:
Submitted by CARLOS EDUARDO SGOTTI (carlos.sgotti@hotmail.com) on 2018-04-27T18:42:48Z
No. of bitstreams: 1
2018_Sgotti_Dissertação_Mestrado.pdf: 10994360 bytes, checksum: 90aa52990d9db0b33dd9950ddfb58289 (MD5)Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-04-27T19:11:29Z (GMT) No. of bitstreams: 1 sgotti_ce_me_ilha.pdf: 10994360 bytes, checksum: 90aa52990d9db0b33dd9950ddfb58289 (MD5)
Made available in DSpace on 2018-04-27T19:11:29Z (GMT). No. of bitstreams: 1 sgotti_ce_me_ilha.pdf: 10994360 bytes, checksum: 90aa52990d9db0b33dd9950ddfb58289 (MD5) Previous issue date: 2018-02-28
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A falha catastrófica de caixas de engrenagens acarreta em perdas de produção e custos de manutenção. O elemento mecânico que mais falha em uma caixa de engrenagens é o próprio par engrenado. Estas falhas geralmente ocorrem devido a defeitos pontuais nos dentes como desgaste severo e presença de trincas, contrariando os fatores de segurança previamente definidos por normas referentes aos critérios de falhas em engrenagens. O monitoramento da condição do par engrenado busca avaliar parâmetros representativos dos mecanismos de falha do par engrenado. As técnicas de monitoramento da condição mais utilizadas são a análise de vibrações e análise de lubrificantes. Este trabalho realiza uma revisão bibliográfica de técnicas de monitoramento da condição. A parte experimental consiste na avaliação de uma bancada sob três condições: desgaste severo ao longo da vida útil da engrenagem; engrenagem entalhada para simulação de trinca; engrenagem com variação do entalhe para simulação de uma propagação de trinca. A condição da bancada foi avaliada utilizando técnicas de tratamento de sinais de vibração como TSA, sinal residual, demodulação temporal e análise estatística via PDF beta e; técnicas de análise de lubrificantes como contagem de partículas e espectrometrias de raios-x e infravermelho. Todas as técnicas se mostraram adequadas na avaliação da evolução do desgaste excetuando a espectrometria de infravermelho. Apenas as técnicas de vibração se mostraram adequadas para identificar a presença do entalhe. A análise estatística via PDF beta se mostrou útil para identificar a degradação de um dente conforme evolui o tamanho do entalhe.
The catastrophic failure of gearboxes results in production losses and maintenance costs. The mechanical component that most fails in gearboxes are the gears. These failures usually occur before the end of useful life projected by criteria of failure standards due teeth defects as severe wear and cracking. The condition monitoring of gearboxes evaluates parameters which can indicate the mechanism of failure in process in the gear. The most commonly used monitoring techniques of gearboxes are vibration analysis and lubricant analysis. Firstly, this work performs a bibliographic review of condition monitoring techniques. The experimental analysis consists of the evaluation of an experimental workbench under three conditions: severe wear throughout the life of the gear; notched gear for crack simulation and; gear with variation of notch for simulation of a crack propagation. The workbench condition was evaluated using vibration signal treatment techniques such as TSA, Residual Signal, Demodulation, Statistical Moments, Crest Factor and Statistical Analysis using PDF beta and; techniques for analyzing lubricants such as particle counting and x-ray and infrared spectrometry. All the techniques were adequate to evaluate the evolution of wear except infrared spectrometry. Only the vibration techniques were adequate to identify the presence an evolution of the notch. Statistical analysis using PDF beta was useful to identify the degradation of a tooth as the notch size evolved.
10
Brito, F. P. "Thermohydrodynamic performance of twin groove journal bearings considering realistic lubricant supply conditions : a theoretical and experimental study". Doctoral thesis, 2009. http://hdl.handle.net/1822/9884.
Pełny tekst źródłaStreszczenie:
Tese de doutoramento em Engenharia Mecânica (ramo do conhecimento em Tribologia)The smooth operation of the power transmission systems found in many transport vehicles and energy production systems is often limited by the reliability of the bearings which support their rotating shafts. Under high shaft speeds and applied loads, hydrodynamic journal bearings may constitute the only acceptable option for the designer. When predicting the performance of journal bearings submitted to severe operating conditions it is crucial to account for the local variation of the temperature and the viscosity field. Furthermore, the lubricant supply conditions such as lubricant feeding pressure and temperature and the actual groove geometry should be treated realistically in the theoretical analysis. The present report describes the work carried out by the author, focused on the theoretical and experimental study of the performance of twin groove journal bearings operating under steady state. A particular emphasis was put on the analysis of the influence of lubricant supply conditions. The work included the development of a Thermohydrodynamic (THD) model for the analysis of the performance of twin groove journal bearings. The model has been based on the simultaneous numerical solution of the generalized Reynolds and Energy equations within the lubricant film and the heat transfer within the bush body. Special care was taken in the treatment of the phenomena taking place in the vicinity of feeding grooves and the modeling of the ruptured film region. Test programs were carried out at the Laboratory of Tribology and Machine Elements of the University of Minho (LOMT) and at the Laboratory of Solid Mechanics of the University of Poitiers (LMS). The scope of these tests was, on one hand, to provide the scientific community with a wealth of experimental results spanning a wide range of supply conditions and providing an extensive discussion of the phenomena involved. On the other hand, the test programs would allow the validation and refinement of the theoretical model.
O bom funcionamento de muitos sistemas de transmissão de potência em veículos de transporte e em sistemas de produção de energia está frequentemente condicionado pela fiabilidade das chumaceiras que suportam os seus veios rotativos. Em situações onde estão envolvidas velocidades de rotação e cargas elevadas, as chumaceiras radiais hidrodinâmicas podem constituir a única alternativa aceitável para o projectista. Na previsão do desempenho de chumaceiras submetidas a condições de funcionamento severas, torna-se necessário entrar em linha de conta com a variação local dos campos de temperatura e viscosidade. As condições de alimentação (pressão e temperatura de alimentação, geometria dos sulcos) devem também ser tidas em consideração na formulação do modelo teórico. A presente dissertação descreve o programa de trabalhos levado a cabo pelo autor no âmbito de um projecto FCT que se dirigiu ao estudo teórico-experimental do desempenho de chumaceiras com dois sulcos de alimentação axiais funcionando em regime estacionário, tendo sido posto um ênfase particular no estudo da influência das condições de alimentação. Os trabalhos incluíram o desenvolvimento de um modelo termohidrodinâmico (THD) para a previsão do desempenho deste tipo de chumaceiras. Este modelo foi baseado na solução numérica simultânea da equação de Reynolds generalizada, da equação da energia no filme lubrificante e da equação de transmissão de calor através do casquilho. Foi posto um particular cuidado na modelação dos fenómenos que ocorrem na região dos sulcos de alimentação e do fenómeno de ruptura de película. Foi levado a cabo um programa de testes laboratoriais realizado no Laboratório de Órgãos de Máquinas e Tribologia da Universidade do Minho (LOMT) e no Laboratório de Mecânica dos Sólidos da Universidade de Poitiers (LMS). A realização deste programa de testes teve como objectivo, por um lado, a disponibilização de um conjunto de resultados experimentais com uma ampla gama de variação das condições de alimentação e o respectivo estudo dos fenómenos envolvidos. Por outro lado, a realização do programa de testes teve também em vista a validação e o refinamento modelo teórico desenvolvido.
Fundação para a Ciência e a Tecnologia (FCT) - Pojecto POCTI/39202/EME/2001 (in conjunction with the European Union fund FEDER) and later the PhD grant SFRH / BD / 22278 / 2005.
European Union. FEDER - bolsa de doutoramento
Fundação Luso-Americana para o Desenvolvimento (FLAD)
Książki na temat "Lubricant conditions"
1
Cupples, Simon David. Lubricant condition in the upper piston ring zone of single cylinder diesel engines under operating conditions. Leicester: De Montfort University, 1992.
Znajdź pełny tekst źródła
2
Talivaldis, Spalvins, Lewis Research Center i United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., red. Influence of the deposition conditions on radiofrequency magnetron sputtered MoS2 films. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1990.
Znajdź pełny tekst źródła
3
Starbuck, J. M. Tribological evaluation of dual lubricant condition bearing materials for use in low pressure aerospace fuel pump systems. Portsmouth: University of Portsmouth, 2002.
Znajdź pełny tekst źródła
4
Condition Monitoring and Preventative Maintenance Conference (1989 Atlanta, Ga.). Condition Monitoring and Preventative Maintenance proceedings: Presented at the 44th Annual Meeting of the Society of Tribologists and Lubrication Engineers, May 1 - May 4, 1989, Atlanta, Georgia. Park Ridge, IL: Society of Tribologists and Lubrication Engineers, 1989.
Znajdź pełny tekst źródła
5
Evaluation of PS 212 coatings under boundary lubrication conditions with an ester-based oil to 300⁰C. [Washington, DC]: National Aeronautics and Space Administration, 1995.
Znajdź pełny tekst źródła
6
Davis, J. R., red. Gear Materials, Properties, and Manufacture. ASM International, 2005. http://dx.doi.org/10.31399/asm.tb.gmpm.9781627083454.
Pełny tekst źródłaStreszczenie:
Gear Materials, Properties, and Manufacture explains how material-related properties and operating conditions affect the lifetime and performance of gears and the ways in which they fail. It begins with a review of the basic design and configuration of gears and related engineering considerations. It then examines the effect of friction and wear and the role of lubrication in gear failures. It explains how to calculate lubricant film thickness, defines lubrication regimes, and presents guidelines for selecting and applying lubricants for specific applications. The chapters that follow cover gear materials and manufacturing methods, providing details on metals and plastics and processes such as casting and forging, powder metallurgy, injection molding, machining, grinding, finishing, and carburizing and nitriding treatments. The final chapters discuss the types and causes of gear failures and the steps involved in failure analysis. They also explain how to assess fatigue damage and estimate remaining service life and describe the tests that are used to evaluate the durability of gears under load. For information on the print version, ISBN 978-0-87170-815-1, follow this link.
7
Lubricant Analysis and Condition Monitoring. Taylor & Francis Group, 2022.
Znajdź pełny tekst źródła
8
Whitby, R. David. Lubricant Analysis and Condition Monitoring. CRC Press LLC, 2022.
Znajdź pełny tekst źródła
9
Whitby, R. David. Lubricant Analysis and Condition Monitoring. Taylor & Francis Group, 2021.
Znajdź pełny tekst źródła
10
Whitby, R. David. Lubricant Analysis and Condition Monitoring. Taylor & Francis Group, 2022.
Znajdź pełny tekst źródłaCzęści książek na temat "Lubricant conditions"
1
Malaguti, Roney, Nuno Lourenço i Cristovão Silva. "A Well Lubricated Machine: A Data Driven Model for Lubricant Oil Conditions". W Progress in Artificial Intelligence, 549–60. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-86230-5_43.
Pełny tekst źródła
2
Park, Noh A., Daniel A. O'Lear i Kay Lee Kim. "The Use of the Portable Field Falling Needle Viscometer to Determine Engine Oil Contamination by Diesel Fuel under In-Service or Field Conditions". W Standard Guides and Practices that Support the Lubricant Condition Monitoring Industry, 266–78. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2022. http://dx.doi.org/10.1520/stp163420210025.
Pełny tekst źródła
3
Pesthy, Márk, Richárd Takács, Jan Rohde-Brandenburger i Csaba Tóth-Nagy. "Vibroacoustic Investigation of Automotive Turbochargers Focusing on the Effect of Lubricant Temperature and Bearing Conditions". W Vehicle and Automotive Engineering 4, 861–70. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-15211-5_71.
Pełny tekst źródła
4
Whitby, R. David. "Sampling Lubricants". W Lubricant Analysis and Condition Monitoring, 31–49. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003245254-3.
Pełny tekst źródła
5
Whitby, R. David. "Testing New Lubricants". W Lubricant Analysis and Condition Monitoring, 51–67. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003245254-4.
Pełny tekst źródła
6
Whitby, R. David. "Testing Lubricants in Use". W Lubricant Analysis and Condition Monitoring, 69–87. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003245254-5.
Pełny tekst źródła
7
Whitby, R. David. "Physical Tests for Lubricants". W Lubricant Analysis and Condition Monitoring, 125–62. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003245254-7.
Pełny tekst źródła
8
Whitby, R. David. "Chemical Tests for Lubricants". W Lubricant Analysis and Condition Monitoring, 89–123. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003245254-6.
Pełny tekst źródła
9
Whitby, R. David. "Engine Tests for Lubricants". W Lubricant Analysis and Condition Monitoring, 181–87. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003245254-9.
Pełny tekst źródła
10
Riley, N. H. "Lubricant analysis as a condition monitoring technique". W Handbook of Condition Monitoring, 435–49. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-4924-2_17.
Pełny tekst źródłaStreszczenia konferencji na temat "Lubricant conditions"
1
Buck, W. H., i J. R. Lohuis. "Lubricant Effects on Low-Temperature Diesel Engine Cold Starting". W 1994 Subzero Engineering Conditions Conference and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1994. http://dx.doi.org/10.4271/940097.
Pełny tekst źródła
2
Sarabi, Soroush, i David B. Bogy. "Viscoelastic Effects on Lubricant Depletion and Recovery Under Heat-Assisted Magnetic Recording (HAMR) Conditions". W ASME 2016 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/isps2016-9578.
Pełny tekst źródłaStreszczenie:
Heat Assisted Magnetic Recording (HAMR) is a developing data-storage technology in which a laser delivery system is integrated to the conventional HDD air bearing slider that carries the read and write transducers. The laser beam heats a small spot of around 20nm size on the storage media up to few hundred degrees Celsius [1]. This heating causes several effects on the lubricant such as temperature gradient, thermocapillary shear stress, viscosity drop, and evaporation followed by its depletion. Conventionally [2–8], the disk lubricant is considered as a Newtonian viscous fluid that can be fully described by a viscosity parameter μ. However, in rapid heating and forcing conditions like HAMR, the time dependent nature of the lubricant becomes very important. Measurements [9] show that under some conditions the lubricant behaves like a Maxwell viscoelastic fluid that can be described by two parameters: viscosity μ and Maxwell relaxation time λ. Itoh et al. [10] show that the viscoelastic behavior becomes even more considerable in the case of sub-10nm material confinement. Both the Maxwell relaxation time and viscosity can be functions of temperature and lubricant thickness in case of ultra-thin film lubrication. Karis [9] measured Maxwell relaxation time as a function of temperature for a variety of lubricants, such as Z-dol and Z-tetraol. Fig. 1 shows the results of these measurements for both Z-dol and Z-tetraol. Maxwell relaxation time plays a vital role in determining the behavior of the material under thermal and mechanical loads. In order to have a proper understanding of the effect of Maxwell relaxation time, we non-dimensionalize this parameter by the timescale of the problem to introduce a non-dimensional Deborah number De = λU/L. So, De is a function of HAMR temperature T, disk speed U, laser spot size L, and lubricant type. For purely-viscous materials both the Maxwell relaxation time and De are zero and for purely-elastic materials, both are infinity. So in the case of viscoelasticity, if De ≪ 1 the viscosity mode is dominant, if De ≫ 1 the elasticity is dominant, and if De ≈ 1 the material behaves viscoelastically. Therefore, De is good measure for the viscoelastic behavior of the material. Some attempts have been made to fit the lubrication theory for viscoelastic materials using perturbation methods. However these methods require that the Deborah Number be small enough [11]. Fig. 2 shows the Deborah Number as a function of laser spot size for different lubricant temperatures. Accordingly, at the target of a HAMR laser spot size of L = 20nm, the Deborah number is very large and therefore, the material behaves less viscous and more elastic. Therefore, the traditional methods of lubrication theory cannot describe the lubricant’s behavior in this limit. Consequently, we developed anew direct Finite Element Method (FEM) approach to simulate the behavior of the linear viscoelastic Maxwell fluid lubricants under HAMR conditions.
3
May, C. J., i J. J. Habeeb. "Lubricant Low Temperature Pumpability Studies — Oil Formulation and Engine Hardware Effects". W 1989 Subzero Engineering Conditions Conference and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1989. http://dx.doi.org/10.4271/890037.
Pełny tekst źródła
4
Chien, Ssu-Ying, Mark Cramer, Gen Fu i Alexandrina Untaroiu. "Performance of Adaptive Lubricants in a Hybrid Journal Bearing Operating Under Fully Saturated Conditions". W ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-64530.
Pełny tekst źródłaStreszczenie:
Adaptive lubricants involve binary mixture of synthetic oil and dissolved carbon dioxide (CO2). Unlike conventional lubricant oils, the lubricant viscosity not only varies with the temperature within the bearing, but also can be directly adjusted through the CO2 concentration in the system. In this study, we investigated the performance of adaptive lubricants in a hybrid journal bearing considering the synthetic oil to be fully saturated by CO2. The adaptive lubricant analyzed for this study was the polyalkylene glycol (PAG) oils with low concentration of CO2 (< 30%). A three-dimensional computational fluid dynamic (CFD) model of the bearing was developed and validated against the experimental data. The mixture composition and the resultant mixture viscosity were calculated as a function of pressure and temperature using empirical equations. The simulation results revealed that the viscosity distribution within the PAG/CO2-lubricated bearing is determined primarily by the pressure at the low operating speed. When the speed becomes higher, it is the temperature effect that dominates the viscosity distribution within the bearing. Moreover, the PAG/CO2-lubricated bearing can reduce up to 12.8% power loss than the PAG-lubricated bearing due to the low viscosity of PAG/CO2 mixture. Most importantly, we have found the PAG/CO2 can enhance the load capacity up to 19.6% when the bearing is operating at the high speed conditions.
5
May, C. J., i C. R. Smith. "The Importance of Lubricant Low Temperature Performance to Vehicle Operation or “Will it Still Go When it's 30 Below?”". W Subzero Engineering Conditions Conference. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1992. http://dx.doi.org/10.4271/920024.
Pełny tekst źródła
6
Paturi, UmaMaheshwera Reddy, i Narala Suresh Kumar Reddy. "Investigation on Wear Behavior of Electrostatic Micro-Solid Lubricant Coatings Under Dry Sliding Conditions". W ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87201.
Pełny tekst źródłaStreszczenie:
Dry sliding experiences high friction and wear thus influencing the life and quality of the parts under sliding. To provide low friction and improve wear resistance, solid lubricants have an edge over conventional choice. This article features a specific study of the application of solid lubricant in dry sliding operations and presents its influence on wear resistance. Using a pin-on-disc tribometer designed according to ASTM G99 standard, dry sliding wear tests on aluminum alloy AA6351-T6 specimens were performed against uncoated EN31 steel and molybdenum disulphide (MoS2) coated EN31 steel discs. In this study, counter surfaces (discs) were coated with micron sized MoS2 solid lubricant powder particles using electrostatic spray coating (ESC) method. The best results for wear volume and friction coefficient (minimum values) were registered when aluminum specimen slid against MoS2 coated EN31 steel. Outcome of this study shows that the presence of solid lubricant film on disc specimen will greatly influence the sliding performance of pin material in lubricating and preventing wear through reduction in the frictional force due to presence of lamellar structure as a transfer film and favorable change in sliding interaction.
7
Adhvaryu, Atanu, Brajendra K. Sharma i Sevim Z. Erhan. "Process Development and Tribochemical Evaluation of Seed Oil Based Antiwear/Antifriction Additive". W World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63380.
Pełny tekst źródłaStreszczenie:
Antiwear / antifriction additives enhance the ability of lubricant to withstand mechanical stresses of interacting surfaces under boundary lubrication conditions. Majority of the lubricants and additives currently used are petroleum based that are toxic to environment, making it increasingly difficult for safe and easy disposal. There has been an increasing demand for “green” lubricants and lubricant additives in recent years due to concerns about lubricants lost to the environment and increasingly strict government regulations controlling their use.
8
Ito, Shigekazu, Hiroaki Yoshida, Sachihiro Isogawa, Yoshihisa Doi i Kuniaki Dohda. "New Evaluation Method for Lubricant in Forging Process". W ASME 2006 International Manufacturing Science and Engineering Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/msec2006-21024.
Pełny tekst źródłaStreszczenie:
A lubricant plays a very important role in forging. It can reduce the forging load and make for smooth knockout. The tribo-simulator tests that have often been used as standard evaluation methods for metal forming lubricants includes the ring compression test and spike forging test. However, the forging of components such as flange bolt and constant velocity joint is more severe than a spike forging test or ring compression test. Thus, the development of an evaluation method for lubricants for use in more severe conditions is much awaited. We have developed a new evaluation tribometer using backward extrusion with a taper punch. The new device is called a “Taper Cup Tribometer.” The taper cup test can evaluate lubricity under large deformation conditions. In this test, the surface expansion ratio can be controlled by changing the punch stroke. The surface expansion ratio of the new taper cup tribometer is around 15 to 50, as calculated by fine element analysis. The results of lubricant evaluation in cold forging of carbon steel are as follows. Zinc phosphate has a lower forging load than other lubricants, making it clear that it is a superior lubricant. Oil, on the other hand, has a high forging load and poor lubrication characteristics. The taper cup Tribometer can evaluate the friction characteristics of lubricants. Furthermore, MoS2 shows a higher forging load than zinc phosphate in the region of higher surface area expansion ratio around 12. The forging load of oil is higher than zinc phosphate in the region of higher surface area expansion ratio around 4. In this way, the new taper cup tribometer can recognize the forging limit for the lubricant under the forging load.
9
Cann, P. M., i H. A. Spikes. "A Micro-IRRAS Study of Lubricant Degradation Under Thin Film Conditions". W World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-64135.
Pełny tekst źródłaStreszczenie:
This paper studies lubricant degradation in a rubbing contact under thin film conditions. Friction tests have been carried out in an MTM test device using a steel ball/steel disc configuration. The tests were run with a small amount of lubricant present. At the end of the test the disc was retained for analysis. Micro-reflection FTIR spectroscopy was used to analyse the lubricant chemistry within and close to the rubbed track. The technique offers a more direct method for studying lubricant degradation products during rubbing. The results are compared to those from more conventional experimental methods.
10
Michaelis, Klaus, Bernd-Robert Ho¨hn i Andreas Doleschel. "Lubricant Influence on Gear Efficiency". W ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/detc2009-86663.
Pełny tekst źródłaStreszczenie:
Power loss in a transmission is strongly related to the properties of the gear lubricant. Viscosity of the lubricant determines the no-load splash and churning losses. The losses in the EHD regime depend on the base oil type. In the boundary and mixed lubrication regime losses are mainly related to the chemical composition of the additive system. A test method was developed to evaluate the frictional properties of candidate transmission lubricants in relation to a mineral reference oil ISO VG 100 with a typical sulphur-phosphorus additive package. The test results can be expressed in simple correlation factors for no-load, EHD and boundary lubrication conditions, in comparative steady-state temperature development for given mean values of operating conditions, and in a ranking scale of different candidates. For a more detailed analysis of the expected power loss in a transmission in practice the results of the efficiency test can be introduced into an equation for the mean coefficient of gear friction for the respective oil. Thus the test results can be applied to any gear in practice at any operating conditions for any gear geometry. Examples of the influence of viscosity, base oil and additive type on the frictional behavior of gear lubricants and their effect on power loss reduction and energy savings in a gearbox are discussed.
Raporty organizacyjne na temat "Lubricant conditions"
1
Frame, Edwin A., i Douglas M. Yost. Evaluation of High-Temperature Lubricant Under Cyclic Operating Conditions. Fort Belvoir, VA: Defense Technical Information Center, maj 1995. http://dx.doi.org/10.21236/ada294444.
Pełny tekst źródła
2
Doerr, R. G., i T. D. Waite. Compatibility of refrigerants and lubricants with motor materials under retrofit conditions. Office of Scientific and Technical Information (OSTI), grudzień 1995. http://dx.doi.org/10.2172/155420.
Pełny tekst źródła
3
Montemayor, A. F., i E. C. Owens. Comparison of Single Grade and Multiviscosity Lubricants in M60 Tanks under Hot Ambient Conditions. Fort Belvoir, VA: Defense Technical Information Center, sierpień 1988. http://dx.doi.org/10.21236/ada202989.
Pełny tekst źródła
4
Gellman, Andrew J. High Resolution XPS Analysis of New Lubricants and Materials for Tribology Under Extreme Conditions. Fort Belvoir, VA: Defense Technical Information Center, marzec 2001. http://dx.doi.org/10.21236/ada387893.
Pełny tekst źródła
5
Doerr, R. G., i T. D. Waite. Compatibility of refrigerants and lubricants with motor materials under retrofit conditions. Final report, Volume 1. Office of Scientific and Technical Information (OSTI), październik 1996. http://dx.doi.org/10.2172/414627.
Pełny tekst źródła
6
Cao Romero, Julio A., Jorge Reyes-Avendaño, Julio Soriano, Leonardo Farfan-Cabrera i Ali Erdemir. A Pin-on-Disc Study on the Electrified Sliding Wear of EVs Powertrain Gears. SAE International, marzec 2022. http://dx.doi.org/10.4271/2022-01-0320.
Pełny tekst źródłaStreszczenie:
In contrast to conventional powertrains from internal combustion engine vehicles (ICEV), the tribological performance of powertrains of electric vehicles (EVs) must be further evaluated by considering new critical operating conditions such as electrical environments. The operation of any type of electric motor produces shaft voltages and currents due to various hardware configurations and factors. Furthermore, the common application of inverters intensifies this problem. It has been reported that the induced shaft voltages and currents can cause premature failure problems in tribological components such as bearings and gears due to accelerated wear and/or fatigue. It is ascribed to effects of electric discharge machining (EDM), also named, sparking wear caused by shaft currents and poor or increasingly diminishing dielectric strength of lubricants. A great effort has been done to study this problem in bearings, but it has not yet been the case for gears. Considering that EVs powertrains can be configurated with an electric motor coupled to a single-speed or multi-speed transmission, it is expected that shaft currents can also affect gears to some extent. The pin-on-disc test has been widely used to study sliding wear of gear materials under comparable or realistic operating conditions. This accelerated test is effective for screening materials, lubricants and operating conditions allowing evaluations of their friction and wear properties. However, it has not been implemented for studying gear materials under electrified environments. Thus, this paper aims to explore the friction coefficient and wear of gear materials under non-electrified and electrified sliding in a pin-on-disc tester applying typical of EVs powertrain shaft currents during sliding. The tests were carried out at two different DC currents under comparable gear dry and lubricated sliding contact conditions. Friction coefficient, wear volumes and morphologies were evaluated and reported in this work.
7
Doerr, R. G., i T. D. Waite. Compatibility of refrigerants and lubricants with motor materials under retrofit conditions. Final report, Volume IV - pictures. Office of Scientific and Technical Information (OSTI), październik 1996. http://dx.doi.org/10.2172/416982.
Pełny tekst źródła
8
Doerr, R. G., i T. D. Waite. Compatibility of refrigerants and lubricants with motor materials under retrofit conditions. Final report, Volume II - data tables, high pressure refrigerants. Office of Scientific and Technical Information (OSTI), październik 1996. http://dx.doi.org/10.2172/416980.
Pełny tekst źródła
9
Doerr, R. G., i T. D. Waite. Compatibility of refrigerants and lubricants with motor materials under retrofit conditions. Final report, Volume III - data tables, low pressure refrigerants. Office of Scientific and Technical Information (OSTI), październik 1996. http://dx.doi.org/10.2172/416983.
Pełny tekst źródła