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1
Baart, Pieter. „Grease lubrication mechanisms in bearing seals“. Doctoral thesis, Luleå, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26652.
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Rolling bearings contain seals to keep lubricant inside and contaminants outside the bearing system. These systems are often lubricated with grease; the grease acts as a lubricant for the bearing and seal and improves the sealing efficiency. In this thesis, the influence of lubricating grease on bearing seal performance is studied. Rheological properties of the grease, i.e. shear stress and normal stress difference, are evaluated and related to the lubricating and sealing performance of the sealing system. This includes the seal, grease and counterface. The grease velocity profile in the seal pocket in-between two sealing lips is dependent on the rheological properties of the grease. The velocity profile in a wide pocket is evaluated using a 1-dimensional model based on the Herschel-Bulkley model. The velocity profile in a narrow pocket, where the influence of the side walls on the velocity profile is significant, is measured using micro particle image velocimetry. Subsequently, the radial migration of contaminants into the seal pocket is modelled and related to the sealing function of the grease. Additionally, also migration in the axial direction is found in the vicinity of the sealing contact. Experimental results show that contaminant particles in different greases consistently migrate either away from the sealing contact or towards the sealing contact, also when the pumping rate of the seal can be neglected. Lubrication of the seal lip contact is dependent on several grease properties. A lubricant film in the sealing contact may be built up as in oil lubricated seals but normal stress differences in the grease within the vicinity of the contact may result in an additional lift force. The grease, which is being sheared in the vicinity of the contact, will also contribute to the frictional torque. It is important to maintain a lubricant film in the sealing contact to minimize friction and wear. Here the replenishment of oil separated from the grease, also referred to as oil bleed, is of crucial importance. A model is presented to predict this oil bleed based on oil flow through the porous grease thickener microstructure. The model is applied to an axial sealing contact and a prediction of the film thickness as a function of time is made. The work presented in the thesis gives a significant contribution to a better understanding of the influence of lubricating grease on the sealing system performance and seal lubrication conditions.Godkänd; 2011; 20110824 (andbra); DISPUTATION Ämnesområde: Maskinelement/Machine Elements Opponent: Georgia Power Distinguished Professor Richard F Salant, Georgia Institute of Technology, Atlanta, USA Ordförande: Professor Braham Prakash, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet, Luleå Tid: Torsdag den 22 september 2011, kl 09.30 Plats: E231, Luleå tekniska universitet
2
Simmons, Gregory F. „Journal bearing design, lubrication and operation for enhanced performance“. Doctoral thesis, Luleå tekniska universitet, Maskinelement, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25801.
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The increasing introduction of intermittent power sources combined with the de-regulation of electricity markets has led to increased instability in the electrical grid. This has led to increased start-up and shutdown of regulating power sources such as hydro-electric power plants and operation at non-ideal operating states both of which increase the wear and tear on machines. Likewise, the push for a less environmentally intrusive society has raised the importance of utilizing equipment with reduced impact on the natural surroundings.These challenges lead to a need to improve the robustness of existing and new equipment to guarantee their usefulness in a future with increased instability. While many components in hydropower systems require thorough investigation to improve their robustness, this work is focused on the guide/journal bearings which support the rotating portion of power generating machines.This work addresses the journal bearing problem through a multi scaled approach covering small and large scale laboratory experiments as well as investigations of a full scale machine.A journal bearing test machine was constructed to investigate a number of new synthetic lubricants and polymer bearing materials. These tests found that a significant reduction in power loss could be accomplished without significantly affecting the bearing's minimum film thickness by changing from a traditional mineral oil to a high viscosity index oil of much lower base viscosity grade. The high viscosity index lubricants were then improved to reduce start-up friction as well. Further studies were conducted in small scale to determine the optimum lubricant characteristics for the startup problem. This knowledge was used to develop new lubricants to test in the journal bearing test machine which showed great reductions in power loss in the bearing and pumping system as well as greatly reduced bearing operating temperature.Further experimental work led to the development of practical guidance for power plant operators contemplating a lubricant change. This technique focuses on the importance of maintaining equivalent viscosity in the minimum film thickness region after a lubricant change. Efficiency improvements can then be calculated by comparing the viscosity in the bulk of the bearing to that with the original lubricant.Experimental work with polymer bearing facing materials demonstrated the dramatic reductions in break away friction that these materials can provide. A number of polymer composite materials were investigated for their friction characteristics at the moment of the start of sliding, finding that PTFE based materials were far superior to traditional Babbitt metal. This work with polymer faced bearings was extended to testing in a tilting pad journal bearing test rig which allowed for identification of the dynamic characteristics resulting from changes in bearing pad material.Investigations in the full scale with the Porjus U9 unit provided valuable insight into the dynamics of a full scale machine as well as needed data for the improvement of multi-physics models of bearings. Insights from the Porjus U9 experiments clarify many of the design challenges for large journal bearings.The results from this work demonstrate that significant performance improvement of journal bearings is possible through the use of new lubricants, materials, and adjustments in operational methods.Godkänd; 2013; 20130531 (gresim); Tillkännagivande disputation 2013-09-06 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Gregory F Simmons Ämne: Maskinelement/Machine Elements Avhandling: Journal Bearing Design, Lubrication and Operation for Enhanced Performance Opponent: Professor Rob Dwyer-Joyce, Dept of Mechanical Engineering, University of Sheffield, UK Ordförande: Professor Braham Prakash, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Fredag den 27 september 2013, kl 13.00 Plats: D770, Luleå tekniska universitet
3
Paydas, Atil. „An investigation into fluid film lubrication in dynamically loaded bearings“. Thesis, University of Central Lancashire, 1998. http://clok.uclan.ac.uk/19223/.
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This thesis is concerned with the development of a nunerical technique for the computational analysis of ruptured liquid films in both steadily and dynamically loaded bearings. The approach is based on the principle of oil flow continuity. A cavitation algorithm, proposed by H. G. Elrod, was implemented for studies of hydrodynamic lubrication in infinitely long cylinder/plane bearings (i.e. non-conformal contacts) under combined sliding, rolling and normal motion. Difficulties involved in the implementation of this algorithm were investigated in great depth. A new 'improved' method of solution, which is well-suited to the computational analyses of steadily and dynamically loaded bearings, was developed. The improved technique involves the solution of the hydrodynamic lubrication problem for oil film pressures or degrees of lubricant filling in the full film and cavitated regions of a bearing. Detailed studies of cylinder/plane under conditions of both instantaneous and sinusoidal normal motion were performed. The improved solution was shown to facilitate the implicit implementation of the Jakobsson-Floberg-011son boundary conditions (i.e. the inclusion of 'oil film history' phencinena) in dynamically loaded bearing analyses. Detailed comparisons between the oil film history and classical solutions, and published experimental studies were made. Computer programs based on the classical Reynolds equation and the improved method of solution were developed for the analysis of circuTiferentially grooved, finite journal bearings operating under steady-state and dynamic loading conditions. The improved method of solution produced more realistic predictions of performance characteristics, particularly oil film extent, oil flow and bearing power loss. Comprehensive comparisons with published theoretical and experimental studies were made. Encouraging agrenent was obtained between the oil flow continuity analyses and experiments. Journal centre orbit analyses of dynamically loaded bearings, typically found in reciprocating engines, indicated that the oil film history solution may reveal a nunber of new features of time-varying performance characteristics not previously predicted by the classical Reynolds solution.
4
Jamaludin, Nordin. „Monitoring low speed rolling element bearing using stress waves techniques“. Thesis, Cranfield University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341044.
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5
Campbell, Craig Maurice. „Signature analysis techniques for needle bearing defect detection“. Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19539.
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6
Westsson, David. „Simulation of torque caused by the lubrication fluid in a ball bearing“. Thesis, Umeå universitet, Institutionen för matematik och matematisk statistik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-126563.
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7
De, La Presilla Román. „Fretting in Wind Power Pitch Bearings: Micro-Slip Experiments and Bearing Test Rig Design“. Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279489.
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Wind power is the fastest-growing form of green energy production in Europe, today accounting for 15% of the total power demand with 100.000 turbines installed. This tremendous development relied on a massive technological undertaking that must be continued, and even accelerated in order to meet the European Commission’s environmental goals for 2050. Currently, more active individual control of the rotor blades, turning the blade into and out of the wind, has proven its ability to reduce structural loads on the blades and other components significantly, therefore paving the road towards strong cost reductions. To allow for such adjustment, the rotor blades are connected to the rotor hub via pitch bearings. However, these new structural load reduction control strategies force the pitch bearings into a much more demanding operation condition. More frequent positioning activity and often in the form of smaller oscillating motions, when compared to traditional pitch control. This leading to an increased risk of wear damage of the pitch bearing that could fully incapacitate the blade control. At which point the safe regulation of the turbine can no longer be guaranteed and catastrophic failure, such as the loss of a rotor blade, is possible. This project pertains to the design a bearing test rig that can be used to test rolling element bearings with contact conditions that emulate those found in pitch bearings. A novel frameless motor-driven concept is proposed. The concept is aimed towards preventing unnecessary damage of non-test bearings and improving the dynamic performance of the test rig for a given motor capacity. One further objective of the project involved using an existing KTH single contact test rig to study the friction behavior of different lubricants when minute reciprocal tangential displacements are imposed.Vindkraft är idag det snabbast växande området för grön elproduktion i Europa och står med 100 000 installerade turbiner för 15% av den totala elförsörjningen. Denna otroliga utvecklingen har berott på en massiv teknologisk insats som måste fortsätta. För att nå Europakommissionens miljömål för 2050 måste expansionen av grön elproduktion och vindkraft till och med trappas upp. Nyligen har en mer aktiv individuell reglering av rotorbladen, vilket möjliggör att bladen kan styras in- och ut ur vinden, visat sig kunna reducera lasterna på blad och andra komponenter avsevärt, vilket därmed möjliggör stora kostnadsreduceringar. Dessa justeringar möjliggörs genom att rotorbladen ansluter hubben via ett rotorbladslager. Dessa nya lastreducerande reglerstrategier tvingar dock lagren att arbeta under högre belastning jämfört med traditionell reglering av rotorbladens lutningsvinkel. Det här sker genom mer frekvent positionering och ofta som små oscillerande rörelser, vilket leder till en högre risk för slitage på rotorbladslagren, som i sin tur kan leda till förlust av rotorbladsregleringen. När så sker kan inte längre en säker reglering av turbinen garanteras och katastrofala fel är möjliga, så som förlust av rotorblad. Det här projektet avser att utarbeta en design för en lagerprovningsrigg som kan användas för att testa rullager med kontaktvillkor som efterliknar de som återfinns i rotorbladslagren. Ett nytt koncept,m som är baserat på en ramlös motor, presenteras. Konceptet avser att förhindra onödigt slitage hos testriggens motorlager och förbättra de dynamiska egenskaperna för en given motorkapacitet. Projektet innefattar även en studie av friktionsbeteendet hos olika smörjmedel under små upprepande tangentiella rörelser, som utförts med en befintlig testrigg på KTH.
8
Scholes, Susan Claire. „The tribology of hard bearing surfaces for use in hip prostheses“. Thesis, Durham University, 1999. http://etheses.dur.ac.uk/1475/.
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9
Elliott, Tony William. „Highly loaded hybrid journal bearings“. Thesis, Liverpool John Moores University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238639.
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10
Leung, P. S. „An investigation of the dynamic behaviour of floating ring bearing systems and their application to turbogenerators“. Thesis, University of Newcastle Upon Tyne, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384577.
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11
Siripuram, Ravinder Babu. „ANALYSIS OF HYDRODYNAMIC EFFECTS OF MICROASPERITY SHAPES ON THRUST BEARING SURFACES“. UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/309.
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The present thesis is a comparative study of the hydrodynamic effects of a few deterministic microasperity shapes in a thrust slider application. Numerical study based on finite difference methods is used to find the trend of important tribological properties such as friction and leakage. Also, this work utilizes a distinctive and practical approach for comparison by considering constant load conditions, instead of constant film thickness, as is expected in an operating thrust bearing. The results are encouraging and clearly reveal the existence of a transition point for asperity area fraction where a reversal in trends for both the coefficient of friction and leakage is observed. The shapes of asperities affect leakage but, have a negligible effect on coefficient of friction; however, the size and the type of asperity (positive or negative) do influence it. The effects of orientation, on the other hand, are found both on the coefficient of friction and leakage. Triangular asperities exhibit an advantage over the other shapes in terms of leakage. In general, the impact of shapes is distinguishable, more at higher asperity area fractions in accordance with the geometrical differences.
12
Kasolang, Salmiah. „An ultrasonic investigation of various aspects of Hydrodynamic lubrication in a journal bearing“. Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500198.
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13
Al-Makhlafy, A. N. „The influence of compliant material and lubrication properties on squeeze film bearing performance“. Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.635694.
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The current study represents a full investigation into the behaviour of a fluid film squeezed between two circular parallel plates by normal velocity which is produced by three types of loading condition: steadily-applied, impact-loaded, or oscillatory motion, in which the fluid in between the two plates is considered to be Newtonian or non-Newtonian and the solid boundary materials used are either both rigid or one of them is flexible. A mathematical model has been developed to include the effect of the fluid inertia, non-Newtonian fluid film, and flexibility of the solid material in determining the behaviour of a squeeze film bearing. The non-Newtonian power law model has been adopted in the current theoretical analysis, and the compliant surface bearing has been simulated in terms of the deflection of a mild steel diaphragm. The theoretical analysis was also developed to demonstrate the generation of the steady-state force generated in the oil film when it was subjected to an oscillatory squeeze motion and to show the distinction between a fixed and a free bearing system. The theoretical results are presented in graphical form to demonstrate the behaviour of the squeeze film bearing for different lubrication properties and solid material condition in which a comparison of conventional bearing behaviour with compliant surface, non-Newtonian fluid behaviour has been carried out. An experimental test rig was modified to permit a wide range of experiments to be performed utilising up-to-date, computerised data collection and manipulation procedures. A series of tests were carried out and a comparison of the results was made with predicted theoretical solutions and published work. The results of the investigation show that the new theoretical development can be utilised for a wide range of operating conditions and that it has been validated by comparing results with published literature of other workers and also with the results of experiments conducted in the laboratory.
14
Hirst, Derek John. „Failure of the elastohydrodynamic lubrication of ball bearing components at very high speeds“. Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676730.
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15
Maršálek, Ondřej. „Advanced Methods for the Solution of Journal Bearing Dynamics“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234268.
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Náplní této disertační práce je popis komplexní a obecně použitelné strategie výpočetního modelování chování kluzných ložisek, pracujících v režimu smíšeného mazání a uvažujících reálné struktury drsných povrchů obou členů kluzných ložisek – ložiskových pánví a ložiskových čepů. V práci jsou uvedeny a detailně popsány způsoby získání charakteristických popisných dat těchto drsných povrchů a její nedílnou součástí je i popis numerických algoritmů, sloužících k následnému zpracování těchto dat. Dále jsou zde rozebrány implementované výpočetní přístupy k modelování kontaktního tlaku. Ovlivnění hydrodynamické mazací vrstvy kluzných ložisek je dáno velikostí a průběhem faktorů toku, jejichž numerické stanovování je zde detailně popsáno. Alternativní stanovení faktorů toku pomocí analytických funkcí je zde pro úplnost rovněž obsaženo. V závěru práce je uveden popis numerického řešiče modelování chování kluzných ložisek spolu s uvedenými výsledky provedených simulací a jejich diskuzí. Ověření jednotlivých výpočetních modelů, popřípadě porovnání výsledků s výsledky získanými alternativním způsobem, je uvedeno v příslušných kapitolách.
16
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.
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17
Mertz, David Hunter. „Lift-off performance in flexure pivot pad and hybrid bearings“. [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3197.
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18
Mohamed, Mohamed Yousri Abdelmeguid. „Spiral Groove Bearing Multiphysics Modeling“. Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-75650.
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Cone crushers are widely used in the mining, mineral processing and quarrying segments of the industry to crush ores and large rocks. In such machinery, the load to be carried is rather heavy and the motion is gyratory which creates a need for a bearing set that can withstand such severe conditions. Sandvik AB is a high-technology Swedish engineering group specialized in tools and tooling systems for metal cutting, equipment, as well as tools and services for the mining and construction industries. One of their products relevant to the mining industry is the cone crusher which utilizes a 3-piece bearing set to carry thrust load. This bearing can be classified as a Spiral Groove Bearing \footnote{The abbreviation S.G.B will be used interchangeably throughout the thesis.}, and it has been incurred that it wears out rather quickly and is believed to be running under mixed-lubrication conditions where the interfaces in the bearing-set are not fully lubricated. The aim behind this thesis is to create a multiphysics model of this bearing in order to understand deeply how it works and the reasons why it does not perform as expected as well as to predict design improvements which can improve the performance of the bearing-set, thus increasing its operating life. It has been concluded that the bearing operates under severe mixed-lubrication conditions and that the generation of a squeeze film is the only method by which lubrication takes place due to the excessive depth of the grooves which is needed to allow for an adequate amount of cold oil to flow into the grooves and cool the interface as well as to accommodate for a considerable amount of wear particles. In light of the results and insight gathered from the simulations, possible design variations of the bearing which can be advantageous in terms of mitigating asperity friction in the interfaces of the bearing are discussed and tested.
19
Suzuki, Hiroyuki. „Bearing surface optimisation on hydrodynamic lubrication film with vibration-assisted machining and ultrasound reflectometry“. Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/12303/.
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The collapse of full-film hydrodynamic lubrication in a journal bearing often leads to a significant failure of the whole machine. In order to delay such full-film lubrication collapse, surface optimisation by implementing bespoke surface texture has spurred industrial interest. This thesis aims to optimise the journal bearing surface for an automotive transmission, addressing the deficiency of understanding of the effects of bespoke surface texture on hydrodynamic lubricant film formation under real operation by developing an accurate, inexpensive and fast texturing technique to create bespoke surface textures and a non-invasive technique to measure the film thickness. A novel variant of non-resonant vibration-assisted machining was developed using an off-the-shelf piezoelectric actuator to create bespoke surface textures. Surface textures consisting of a repeating radial striation pattern of sine waves were reproducibly generated on the face of the disc work piece (an aluminium alloy AlSi1MgMn and a low-alloyed steel 16MnCr5) in a conventional milling machine when the frequency of the superposed vibration was in phase with the rotational speed of the work piece. The developed device was successfully implemented on shaft work pieces (alloyed steels C40 and SCM420H) in a conventional turning machine also. A journal bearing test platform, which represents operational conditions of an automotive transmission, was developed incorporating a non-invasive ultrasound reflection technique. On the test platform, film thickness measurement was examined under operational conditions in steady-state. The measured film thickness and the attitude angle on the plain journal bearing (98 mm of the diameter with 0.255 of L/D) agreed well with theoretical curves deduced by a classical Reynolds equation with the short-bearing approximation. Film thickness measurements on two textured journal bearings (a rough-meshed by a conventional milling and a fine-meshed by the vibration-assisted machining device) were performed on the journal bearing test platform. The load capacity ratio, i.e. a ratio of the load capacity experimentally measured on the textured bearing and on the un-textured bearing, were 0.40 to 0.59 in the rough-meshed bearing and 1.12 to 1.27 in the fine-meshed bearing. Despite several differences in the geometrical model and test conditions between the present experimental work and the literature CFD works compared, the load capacity ratios were quantitatively similar.
20
Sharma, Subhash Chandra. „Wear reducing additives for lubricants containing solid contaminants“. Queensland University of Technology, 2008. http://eprints.qut.edu.au/20661/.
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Machines operating in dusty environments, such as mining and civil works, are prone to premature failure, leading to production losses. To address this problem, this research project examines the interaction between solid contaminants and the bearing micro-geometry, in lubricated surface contacts. In particular, it seeks to identify anti-wear additives that are effective in reducing wear under abrasive conditions, making machine elements more dirt tolerant.
In general, the influence of antiwear additive is so small that it is difficult to isolate it. Manufactures often make claims about their antiwear products, which are difficult to verify. Hence, there is a need to characterising the antiwear additives available with a well-defined parameter, making it easier for consumers to compare the efficacy of various additives, and be able to select the most suitable additive for a given environment.
Effect of micro-geometry parameters such as radial clearance, out-of-roughness and surface roughness was examined and a Film Shape Factor (FSF) – also termed gamma ratio – has been proposed for ensuring adequate separation of journal bearings operating in hydrodynamic lubrication regime, where the out-of-roundness values are higher than the surface roughness values.
In this research, an experimental study has been conducted on journal bearings, to examine the influence of five antiwear additives on the bearing wear and micro-geometry. The test additives were provided by the industry partner without revealing their chemical identity or composition; however, these included some of the most commonly used antiwear additives. The tests were performed under three conditions: pure base oil, base oil containing contaminants, and base oil containing contaminants treated with five different additives.
The experiments were aimed at choosing one wear measuring technique that evaluates the performance of an individual additive reliably, and based on this technique the additives were characterised. To achieve these objectives, a multi-wear parameter approach (MWPA) was developed, which employed three main wear measurement methodologies, i.e. weight loss, micro-geometry and particle counts –to examine the effect of the antiwear additives. Minimum oil film thickness was also measured to study the lubrication status in the bearing contacts. The MWPA helped in comparing different wear measuring methods, and in selecting the most reliable one. This approach also helped in developing short duration wear tests, thereby saving time, while still getting reliable results without repeating these.
Wear experiments were performed on seven sets of bronze bearings and steel sleeve shafts. The test contaminant was 16 micron Aluminium oxide Al2O3 powder mixed in oil with 4% concentration by weight. These solid contaminants were treated with five different antiwear additives to study their influence on the bearings. Bearings were operated such that the minimum oil film thickness in the bearing was equal to the size of the contaminants. These tests were run for a constant sliding distance of 7536m.
The results showed that most of the wear measuring techniques do not suit heavily contaminated test conditions. However, the out-of-roundness technique proved to be the most reliable and practical. Based on this technique a methodology was developed which gave a wear characteristic number (N). A unique value of N can be derived for each additive, thereby ranking the additives for their efficacy.
The finding of this research provides a better understanding of the methodologies used for measuring wear in journal bearings subjected to dusty environments, and examines the efficacy of each one of these. The wear characteristic number (N) can be used by manufacturers with support from international standards organisations, so that the users can confidently choose the most appropriate antiwear additive for their application.
Machines operating in a dusty environment, such as mining industry and civil works are prone to premature failure with subsequent production losses. In response to this problem, this research project examines the interaction between solid contaminant particles and the lubricant film micro-geometry in lubricated surface contacts. In particular, it seeks to identify lubricant anti-wear additives, which are effective in reducing wear under abrasive conditions and thus making machine elements more dirt tolerant.
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Rowan, D. „Design and development of a high-speed test facility and the measurement of the fluid film characteristics of journal bearings“. Thesis, Cranfield University, 1998. http://dspace.lib.cranfield.ac.uk/handle/1826/11357.
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In the theoretical analysis of high speed rotor bearing systems, it is common to use
four displacement and four velocity based coefficients, which characterise the
behaviour of the lubricating fluid film. Although a great deal of work has been
published establishing theoretical models of all types of hydrodynamic journal bearings,
the large amount of experimental work has centred on relatively low speed conditions.
This work presents a contribution to the experimental study of the static and dynamic
characteristics of oil films in journal bearings used in high-speed rotating machinery.
The main objectives of the work are:
• To devise new experimental techniques for the measurement of dynamic
coefficients suitable for use at high rotational speeds
• To design, manufacture, assemble and commission a test facility to measure
the static and dynamic characteristics of journal bearings at speeds up to
30000 rpm
• To determine the static and dynamic characteristics of a 5 Pad Tilting Pad
Journal Bearing Unit of 80 mm diameter at speeds up to 25 000 rpm using the
said test facility.
New techniques are particularly necessary for the measurement of velocity coefficients
because these invoke the necessity of imposing a velocity on to the bearing housing
and previous techniques have utilised synchronous motion of the bearing.
Consequently a new experimental procedure for measuring the four velocity or
damping coefficients of an oil film journal bearing from imposed dynamic "orbits" has
been devised called the "double pulse" technique. All four velocity coefficients are
derived from one imposed journal centre dynamic orbit and, therefore may be regarded
as being obtained at the same time. The method requires the production of a "cross-
over" point similar to that of a "figure of eight" shaped orbit and utilises the "cross-over"
point therein.
Coefficients are initially evaluated in a co-ordinate system, which is chosen to align with
the designated parts of the measured orbit. Each coefficient is then evaluated from
single values of instantaneous imposed force and resulting journal centre velocity.
Coefficients are them converted into any other desired axes system. The result is a
simpler experimental procedure, with reduced uncertainty compared to hitherto existing
methods.
The use of non-sinusoidal excitation of the oil film was explored, in the form of applying
a step-pulse train load pattern to produce a cross-over pattern in the journal
displacement ·orbit'.
Experimental tests were completed on a tilting pad bearing at speeds up to 15 000 rpm
inclusive. At speeds above this, the bearing exhibited a vibrational response, which
precluded the accurate measurement of journal centre displacement.
22
Ujvari, Szerena Krisztina. „Journal Bearing Friction Optimization“. Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-60669.
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Engine downsizing, improving fuel efficiency while satisfying the environmental legislations are one of the main driving forces in developing new solutions for passenger cars.Engine main bearings, are journal bearings which support the crankshaft and operate principally in full film lubrication. Defining the optimum design parameters of the bearings which can provide low friction and high durability for automobiles represents a multi-variable problem.Being the supporters of the main shaft driven by the internal combustion engine, main bearings are subjected to strenuous operating conditions. These include high loads and pressures amongst others. The trend in lubricant selection for these components is shifting towards choosing engine oils with lower viscosity to further reduce fuel consumption. Simultaneously with the shift in oil, new solutions for controlling the geometry and the topography on the micro-scale are becoming available. Three main bearing top layers plated on a conventional aluminum alloy containing tin and silicon were selected for the study. The top layers, one bismuth based and two newly developed polymer based, were investigated for their frictional and wear performance.In order to study experimentally the influence of different design parameters on bearing performance a test rig and a methodology was developed. The selected engine main bearings were tested in lubricated condition with two oils having different viscosity. Pre - and post test analysis of the shaft surface roughness was performed using white light interferometry. The wear performance of the bearings was measured both as mass loss and surface topography.The results suggest that the developed test rig can be used to simulate close to running condition testing. The measurement method and set up shows good consistency at a load of 2000 N, but indicates inconsistency in set up at 500 N.It is found that the newly developed engine main bearing top layers have promising frictional and wear performance, providing a reduction in friction by up to 20%.
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Harangozo, Andrew Vilmos. „An investigation into the effects of lubrication methods on the performance of the tilting-pad journal bearing“. Thesis, Brunel University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257671.
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Gebretsadik, Daniel. „Tribological Behaviour of Pb-free Engine Bearing Materials“. Licentiate thesis, Luleå tekniska universitet, Maskinelement, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16981.
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Engine bearings are amongst the most critical components of an internal combustion engine that support and allow smooth rotation of the crankshaft. They are designed to operate under hydrodynamic lubrication condition where the bearing and shaft surface are separated by a thick lubricant film. However, they also occasionally operate under mixed and boundary lubrication conditions particularly during starting, stopping and load, speed and temperature variations. Under these conditions, tribological performance of bearing materials is crucial for the satisfactory performance of theengine. Traditionally, the most extensively used engine bearing materials have been Copper-Lead (Cu-Pb) based linings and Pb based overlays because of the friction reducing properties of Pb. However, due to the adverse health and environmental impact of Pb, there is growing emphasis on restricting the usage of Pb in engine bearings. Owing to this, new Pb-free bearing materials that provide at least comparable or superior tribological performance to that of Pb containing materials are being developed. Someof these materials have already been introduced in engine bearing applications. There are, however, only few research results in the open literature as to how these new engine bearing materials would perform in mixed and boundary lubricated conditions. The objective of this work is to evaluate and understand the tribological performance of selected Pb-free engine bearing materials and compare their performance with that of the traditional Pb-containing material. To understand the damage mechanisms in thetraditional Pb-containing bearings, a full set of main and connecting rod bearings from field test run in Euro V truck engines in long haulage application with European diesel fuel and with slightly longer oil drainage interval were investigated. Furthermore, laboratory tests on Pb-free engine bearings with different compositions of lining and overlay materials were carried out with a block-on-ring test set up in order to evaluate their tribological performance. For this study, aluminum-tin (Al-Sn) based lining withno overlay; Cu-based linings with overlay of polyamide-imide (PAI) containing MoS, 2 and graphite, Al-Sn based overlay and Sn based overlay were studied. Cu-Pb lining with Pb-based overlay was also studied as a reference.Investigations on a full set of main bearings and connecting rod bearings from field test revealed that the major damage mechanisms were 3-body abrasive wear leading to exposure of lining material, flaking of overlay material due to surface fatigue, formation of compound layer composed of Sn, Cu and Ni and cavitation damage.Laboratory tests on Pb-free bearing materials have shown that Al-Sn based lining with no overlay shows higher friction than the other materials at lower rotational speed. For Al-Sn based lining and Pb-based overlay materials, the decrease in friction is relatively sharp as rotational speed increases compared with the PAI based overlay. Test samples with overlay of PAI containing graphite and MoS 2 exhibited better friction and wear properties than Al-Sn based and Pb-based materials. Under steady-state conditions,Pb-containing bearing material shows higher wear and Al-Sn based material hasshown higher friction. In addition, Sn-based and Pb-based overlays have shownsimilar friction behaviour when rotational speed is varied. For relatively longer test durations, samples with Sn overlay exhibited comparable friction and wear with that of Pb-based overlay material.Godkänd; 2014; 20141119 (dangeb); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Daniel Gebretsadik Ämne: Maskinelement/Machine Elements Uppsats: Tribological Behaviour of Pb-free Enginge Bearing Materials Examinator: Professor Braham Prakash, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Dr Donald McCarthy, Volvo Construction Equipment, Eskilstuna Tid: Fredag den 19 december 2014 kl 10:00 Plats: E231, Luleå tekniska universitet
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Meng, Qingen. „Elastohyrodynamic lubrication in metal-on-metal artificial hip joints with aspherical bearing surfaces and complex structures“. Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535667.
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Knowles, Sean William. „An Investigation of Foil Thickness on Performance for Oil – Free Bearings“. Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1237480316.
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Vrček, Aleks. „Micro-pitting and wear characterization for crankshaft roller bearing application“. Licentiate thesis, Luleå tekniska universitet, Maskinelement, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68418.
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Efficiency of internal combustion engines (ICEs) is far from optimal. Due to the continuously increasing demands on CO2 regulations, automobile industries are forced to improve such efficiency. A crankshaft roller bearing (CSRB) can lead to significant improvements in engine efficiency. However, before this can be implemented into an actual engine, several challenges have to be addressed. One such challenge is the satisfactory performance of CSRB. The current crankshaft limits the service life since it must act as a roller bearing raceway. Therefore, better material properties are required for the use of CSRB in crankshaft applications. In order to select suitable material for the CSRB, development of several characterization methods is required. These methods are based on failure modes that are expected to occur in the actual application. Surface initiated fatigue was shown to be the main failure mode that could lead to complete failure of such a component. The following three characterizations needs are identified: material characterization, lubricant characterization and surface roughness characterization. Two of these methods are partially part of this thesis. Material characterization is required to select the optimal steel candidate for the CSRB component. A method was developed to assess the damage modes on a reference 100Cr6 steel pair under conditions prevalent to CSRB application. However, fully formulated oil was excluded from this investigation and only low-additive oil was employed. Micro-pitting and wear damage modes were identified and were later assessed. Different surface roughness combinations were tested, from where micro-pitting regions were identified. In addition, the effects of surface hardness and sliding on micro-pitting and wear were investigated. It was found that hard steel contacts are more prone to micro-pitting damage compared to soft ones, but less susceptible to mild wear. In addition, higher sliding increases the degree of micro-pitting and wear. Lubricant characterization was performed to optimize the engine oil formulation for rolling contacts. A method to assess different engine oils in terms of micro-pitting and wear damages of rolling contacts was employed. The effect of viscosity, additive chemistry and different mixtures of base oils on aforementioned performance were presented and discussed. In addition, lubricant characterization will provide in-depth knowledge for engine oils’ manufacturers to improve engine oil formulations for satisfactory performances of CSRB design.
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Shan, Lei. „Fluid pressure distribution at the interface between compliant and hard surfaces“. Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17788.
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Cubillo, Adrian. „Physics-based approach to detect metal-metal contact in the hydrodynamic bearing of a planetary transmission“. Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/11585.
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Health condition monitoring, commonly referred as Integrated Vehicle Health Management (IVHM) for fleets or vehicles, studies the current and future health state of a system. Health monitoring techniques based on data driven approaches have proven successful in several areas and are easily scalable; however they do not rely on the understating of the physics of failure; whereas Physics-based Model (PbM) approaches require expert knowledge of the failure modes and are based on the understanding of the component behaviour and degradation mechanisms. The development of IVHM is particularly challenging for legacy aircraft due to the restrictive regulations of the aerospace industry. This thesis proposes a novel PbM technique to detect metal-metal contact in hydrodynamic bearings. The planetary transmission of an aircraft’s Integrated Drive Generator (IDG) is used as a case study. Research on the detection of metal-metal contact in hydrodynamic bearings has focused on data driven approaches using vibration or acoustic emissions rather than on PbMs. The proposed technique estimates metal-metal contact by modelling the physical phenomena involved in the failure mechanism and only the speed, load and temperature are required as inputs, all of them available in the IDG and not requiring any additional sensors. The study of metal-metal in hydrodynamic bearings in the field of tribology has focused on mixed lubrication models of the whole bearing, or computational models accounting for local effect under the hydrodynamic lubrication region. In addition to the IVHM technique, this thesis contributes to the field of tribology by proposing a computational mixed lubrication model capable of studying metal-metal contact locally along the lubricated surface of the bearing. Experimental results of a plain journal bearing have been used to validate the PbM and a replica of the transmission of the IDG has been tested to evaluate the effectiveness of the proposed technique at detecting metal-metal contact.
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Tilson, Nial Robert. „An Experimental Evaluation of Micro-pitting Performance of Two Bearing Steels“. The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365695328.
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Tekin, Koray Serdar. „Design And Construction Of Boundary Lubricated Bearing Test Rig And Wear Analysis In Earthmoving Machinery“. Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612751/index.pdf.
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Excavators which used as earthmoving machinery are exposed to heavy loads and operate long hours repeatedly. The forces that are transmitted trough pin bearings are observed to cause failure due to wear. Therefore, durability of bearings is crucial for excavators. The aim of this study is to perform wear analysis of excavator bearings running in boundary lubrication regime. A hydraulically powered test rig, which simulates the operating conditions of excavator bearings is designed and constructed. Wear is obtained applying both force and relative motion between pin and bearing on the test rig. Several tests are performed in this test bench. Force and material type are varied as the factors influencing wear. Results are compared and the effects of the factors on wear are determined.
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Hehir, Ryan Thomas. „A CFD Investigation of the Two Phase Flow Regimes Inside the Bearing Chamber and De-aerator of a Jet Engine“. Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73386.
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In a jet engine air and oil are mixed during removal from the bearing chamber. Before the oil can be recycled back into the system it must be separated from the air. This is accomplished through use of a de-aerator and breather. The oil air mixture enters the de-aerator first. The de-aerator is a vertical cylinder in which the air and oil enter from the top of the system. Gravity then pulls the oil down as it circulates along the outer wall of the de-aerator. The air is forced out through a top hole and sent to the breather where any oil droplets which remain are furthered separated. A pedestal is located near the bottom of the de-aerator. The pedestal creates a gap between itself and the de-aerator wall. Ideally this gap should be large enough to allow oil to flow through the gap without pooling on the pedestal, but small enough so that air does not flow through the gap. The oil will pool up on the pedestal and reduce the efficiency of the system. In this research, a 30° conical pedestal with a gap of 10.7% was tested. The results showed that the pedestal gap of 10.7% is too large and allows air to flow through the gap. The maximum water was 8.5% and the average water thickness was 5.11%. After studying both the previous experimental data and current CFD data, it is recommended further testing be conducted on pedestal gaps between 8.5% and 9.5%.Master of Science
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Gralde, Marcus, und Tómas Rúnar Sölvason. „Realisation and evaluation of a start-stop journal bearing test-rig“. Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156713.
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While there has been substantial body of work in the field of journal bearing research, much of it is today theoretical or simulated due to today’s computing power. Scania produces experimental data from motor testing, but these are expensive and time consuming. Furthermore there is a difficulty in keeping a sufficiently controlled environment, which at times makes it hard to draw conclusions from testing results. They therefore wish to develop a test-rig which can evaluate friction and wear in journal bearings. This thesis is a continuation of a project in the course Advanced Machine Design given at KTH Royal Institute of Technology. During this thesis the test-rig has been manufactured, built, and evaluated. Furthermore software for the test-rig was developed. Information on journal bearings, risk assessment and signal noise handling were sought. Mechanical development was done with Autodesk Inventor, while Matlab was used for software development. Factorial design was utilised when designing tests and compared to a simple theoretical model. Test results showed promising results for Stribeck curve-producing tests, with good resemblance to known frictional values and trends. Furthermore the test-rig showed good repeatability for replicated tests and produced wear on the bearing shells used. During a prolonged test, the shaft and support-bearings were damaged and requires servicing to be in an operational state. The test-rig requires to be further verified, but the tests that were carried out showed valuable and reliable information on wear and frictional values. Keywords: journal bearing, hydrodynamic lubrication, wear, start-stop, test-rigÄven om en betydande mängd forskning inom glidlager och fullfilmslager har genomförts så är med dagens datorkapacitet en stor del av resultaten numera teoretiska eller simulerade. Medan Scania producerar experimentella resultat, så är dessa dyra och tidskrävande. Vidare är det ibland svårt att hålla en tillräckligt kontrollerad miljö för att dra slutsatser från proverna. Med en dedikerad testrigg som kan tillförlitliga resultat tas fram billigare och snabbare. Detta examensarbete är en fortsättning av kursen Avancerad Maskinkonstruktion som ges vid Kungliga Tekniska Högskolan. Under detta examensarbete har testriggen tillverkats, byggts och utvärderats. Vidare har programvara för testriggen utvecklats. Informationssökning gjordes på glidlager, fullfilmslager, riskbedömning och signalbrushantering. Mekanisk utveckling har gjorts i Autodesk Inventor, medan Matlab användes för mjukvaruutveckling. Faktorial design har nyttjats vid utformningen av tester. Resultaten jämfördes med en enkel teoretisk modell. Testresultaten visade lovade resultat för Stribeck kurva-producerande tester, med god likhet till kända friktionsvärden och trender. Testriggen visade god reproducerbarhet vid replikerade tester. Testriggen producerar slitage på samtliga testade lagerytor. Under ett längre test så har axel och stödlager skadats, varför service behövs för att testriggen skall vara i brukbart skick. Testriggen kräver ytterligare verifiering, men resultaten från de prov som genomförts visar att test-riggen ger värdefull och tillförlitlig information om slitage och friktion kunna utrönas. Nyckelord: glidlager, hydrodynamisk smörjfilm, nötning, start-stop, testrigg
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Salomon, Johan. „New materials in sliding bearings“. Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175891.
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Increasing demands for lower emissions from heavy trucks and buses creates new demands on the components in the engine. One such component is the journal bearing which is used at many positions in the engine. Implementing a start-stop system in a truck engine leads to that the crankshaft journal bearing gets worn out too quickly. A journal bearing is a sliding bearing with a constant flow of oil. When the journal starts rotating an oil film is formed between the bearing and the journal, separating the journal from the bearing surface when the rotational speed is high enough. When this happens a hydrodynamic oil film is formed. During start and stop the bearing and journal passes through boundary and mixed lubrication regimes. The increase in starts and stops leads to a vast increase in the time that the bearing is experiencing boundary and mixed lubrication. During these regimes the journal comes in contact with the bearing surface and eventually leads to wear. This thesis has compared two new materials provided by Höganäs AB with an existing bearing as a reference material. The new materials were laser cladded onto bearing shells and sent to Scania for grinding and testing. The thought was to use a start-stop test rig at KTH that simulates start-stop cycles. The reference bearings were first run in the test rig, but when the shells with the new materials arrived it turned out that they would not fit in the test rig. This created the need for a new test method on a short notice and a reciprocating tribometer at Scania was chosen. The tribometer underwent a number of modifications to be able to fit the samples. Five tests with each new material and the reference material were carried out. The tests ran for 60 minutes except for a long term test that ran for 600 minutes. The results showed that the material designated “S”, which had a solid lubricant, had a coefficient of friction similar to the reference material, but produced less wear and could handle a higher load. The thesis has also proved that the start-stop test rig at KTH works well and can deliver reliable results.På grund av skärpta miljökrav för tunga lastbilar och bussar ökar kraven på motorns komponenter. En av dessa komponenter är radialglidlager som används på många platser i motorn. Implementering av start-stoppsystem i en lastbilsmotor leder till att vevaxellagren slits ut i förtid. Ett radialglidlager är ett glidlager med ett kontant tillflöde av olja. När axeln börjar rotera skapas det en oljefilm mellan lagerytan och axeln. När rotationshastigheten är tillräckligt hög bär oljefilmen lasten och separerar axeln och lagerytan. Då har det bildats en fullfilm. Under start och stopp passerar lagret genom smörjregimerna gränsskiktssmörjning och blandsmörjning. Ökningen av start och stopp leder till en stor ökning av tiden som lagret upplever gränsskiktsoch blandsmörjning. Under dessa regimer är axeln och lagerytan i kontakt vilket leder till nötning. Detta examensarbete har jämfört två nya material från Höganäs AB med ett existerande lager som referens. De två nya materialen påsvetsades på lagerskålar och skickades till Scania för att slipas och testas. Tanken var att använda en start-stopprigg på KTH som simulerar startstoppcykler. Till att börja med kördes referenslagren i riggen, men när lagerskålarna med de nya materialen levererades visade det sig att de inte passade i testriggen. Detta innebar att en ny testmetod behövdes tas fram med kort varsel och valet föll på en reciprocerande tribometer på Scania. Tribometern var tvungen att modifieras för att proverna skulle passa. Fem test med varje material utfördes. Varje test tog 60 minuter, förutom ett långtidstest som kördes under 600 minuter. Resultaten visade att materialet kallat ”S”, vilket inkorporerade ett fast smörjmedel, hade en friktionskoefficient som liknade referensmaterialets, men producerade mindre nötning och klarade av en högre last. Examensarbetet har också kunnat påvisa att start-stoppriggen på KTH fungerar väl och kan leverera konsekventa resultat.
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Žatko, Miroslav. „Výpočtová analýza dynamických vlastností axiálních ložisek“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229361.
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This master´s thesis solves the problem of stationary viscous flow of incompressible fluids in thin layers of fluid film lubrication in fixed pad thrust bearings. The parametric computational model of oil domain was created for investigation the distribution of pressure, velocity and thermal fields together with the determination of the basic parameters as axial force, heating up and friction loss. Subsequently this model was applied for investigation influence of uneven bearing clearance. The problem task was solved by final volume method in Ansys CFX 12.0 software.
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Snyder, Troy Alan. „On Hydrodynamic Lubrication using Perturbed Reynolds equation and CFD-FSI: Static and Dynamic Characteristics of Compliant Marine Bearings“. University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron157552061871739.
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Miranda, Gregorio do Couto. „The Detection of Journal Bearing Cavitation with Use of Ultrasound Technology“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1459969270.
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Trevisan, Renato. „Utilização de medições ultrassônicas de vibração e da emissão acústica para implantação de lubrificação base-condição visando a prevenção de falhas em mancais de rolamentos“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/35619.
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Este trabalho tem por objetivo apresentar uma técnica de identificação de falhas em mancais de rolamento até então praticamente inexistente no Brasil. Ela refere-se à mudança da tradicional lubrificação base-tempo, baseada em recomendações de fabricante e fórmulas retiradas de ábacos clássicos para a lubrificação base-condição. Mancais de rolamento são peças obrigatórias em uma infinidade de equipamentos, em sua grande parte, rotativos. A técnica mais difundida de identificação de falhas é a análise de vibração, em seus mais diversos graus de tecnologia embarcada. No entanto, o que ocorre por inúmeras vezes é a identificação da falha já em um estágio onde a falha não pode mais ser reparada, e sim apenas ter seu desenvolvimento monitorado. Isto ocorre devido à freqüência de coleta de dados ser baseada em cartas de severidade, e a falha pode se propagar de uma forma acelerada entre as medições realizadas. A partir desta nova técnica o que se busca é proporcionar à técnica de manutenção preventiva conhecida por lubrificação, que por muitas vezes é tão menosprezada dentro das indústrias, a aquisição de informações importantes a partir de coleta das vibrações ultrassônicas emitidas pelos mancais. Desta forma se fornecem condições para que a lubrificação atue de modo a auxiliar a técnica de análise de vibração, evitando lubrificações em demasia e prevenindo a falta de lubrificante nos mancais, a partir de inspeção baseada em condição.The aim of this work is to develop a root cause fail identification technique in rolling bearings fairly known in Brazil. This technique refers to the changing from traditional time-based lubrication, done upon manufacturers’ recommendation and formulas taken from classic abacus to condition based lubrication. Rolling bearing are mandatory parts in a large amount of equipments, especially in dynamics. The most known technique for fail identification is vibration analysis, used with different technologies. However several times the identification is made in a stage where the problem can no longer be fixed only monitored. That situation happens because of data collection is made based in severity charts, and fail can propagate in a fast mode between collections. With this condition based technique, it follows to purpose to the other predictive maintenance technique known as lubrication, which is so many cases is undervalued inside industries, the acquisition of important information from bearing ultrasonic vibration data collection. Since this important model apparatus are given to that lubrication acts in order to help vibration analysis technique to avoid over greasing and preventing bearing lack of lubrication, inspection based on condition.
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Kuzník, Bořek. „Konstrukce bloku motoru leteckého motoru“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230795.
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This thesis describes the problems of the engine block and crankcase. There is solution of structural design and contains the engineering design of invert six-cylinder engine block with water cooling. Thesis deals with connected equipment and drives. Engineering design is verified by finite elements analysis for the determination of strenght and durability. The ending of thesis analyzes the production methods of designed engine block.
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Sikora, Vojtěch. „Optimalizace mazacího systému pro mazání ložisek válcovacích stolic“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443758.
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The thesis focuses on the optimization of the central lubrication system for the lubrication of rolling bearings of rolling mills in the operation continuous wire rod mill. The work is divided into theoretical and practical part. The first part of the theoretical work is focuses on the search of rolling and tribodiagnostics. The next part focuses on the description of modern central lubrication systems, explanation of their principle and practical use. The practical part explains the function of the old lubrication system for rolling mill bearings with an analysis of its problems. Next is described the technical design of a new central lubrication system, its application into operation and its actual commissioning are described. The last part of the thesis is the conclusion and evaluation of the benefits of the new central lubrication system compared to the old one.
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Sabbagh, F. „Wear characteristics of cast iron and steel under boundary lubricated conditions : A study of boundary lubricated wear of cast iron piston rings and its relation to their wear under engine conditions, with a comparative wear study on roller bearing steel“. Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381032.
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Axelsson, Erik, und Samuel André. „Studie av smörjsystem“. Thesis, Örebro universitet, Akademin för naturvetenskap och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-16098.
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Målet med detta arbete är att undersöka smörjsystemet på två utsatta leder på en Boomer E2C. Förfrågan om examensarbetet kommer från Atlas Copco Rock Drills AB i Örebro som också tillverkar maskinen. Atlas Copco Rock Drills AB har idag ett fettsmörjningssystem som upprätthåller funktionerna på lederna. Uppgiften är att sammanfatta och utvärdera dagens system samt att finna nya lösningsförslag som skulle kunna ersätta eller delvis ersätta systemet. Information har hämtats från dokumentation, ritningar och samtal med konstruktörer på företaget. Efter att alla förutsättningarna för lederna specificerats så har lösningsförslag sökts. Genom att träffa lagerleverantörer och söka artiklar så har idéer formats. Brainstorming har använts för att kunna se nya lösningar. Undersökningen har visat att det finns problem med dagens lösning vad gäller slanghaverier och driftstopp i fält. Atlas Copco AB uttrycker även att kunskapen och dokumentationen angående systemet är otillräckligt. Efter artikelsökning så kan konstateras att forskningen och kunskapen på området med tungt belastade, oscillerande och fettsmörjda leder är liten. Dimensionering sker ofta med hjälp av erfarenhet och med tankesättet ”det har fungerat förut”. När lösningsförslagen har jämförts så har detta gjorts genom att använda metoden AHP (Analytic Hierachy Process). Med denna metod så jämför man kriterierna från kravspecifikationen med lösningsförslag så att man matematiskt kan räkna fram ett vinnande lösningsförslag. Resultatet visar att en smörjfri lösning skulle teoretiskt vara att föredra. Denna skulle tillverkas av en modern polymer och kompletteras med en inre tätning och ett yttre skydd. Atlas Copco rekommenderas att testa de olika förslagen för att komma fram till vilken som är bäst lämpad för applikationen.The goal of this work is to investigate the lubrication system on two exposed joints on a Boomer E2C. The request for the thesis comes from Atlas Copco Rock Drills AB, Örebro, which also manufactures the machine. Today Atlas Copco Rock Drills AB has a grease lubrication system that secures the function of the joints. The task is to summarize and evaluate the current systems and to find new solutions that would be able to replace or partially replace the current system. Information was gathered from documents, construction drawings and conversations with engineers at the company. Solutions and ideas have been formed by meeting stock suppliers and searching for articles. Brainstorming has been used in order to find new solutions. The investigation has shown that there are problems with the current solution in terms of hose failures and downtime in the field. Atlas Copco AB also expresses that there is a lack of documentation and knowledge regarding the lubrication system. After the various article searches it became clear that research and knowledge in the area with heavy duty, oscillating and grease lubricated joints is insufficient. The design is often done with the help of experience and with the mindset "it has worked before." When the solutions and ideas have been compared, this has been done by using AHP (Analytic Hierarchy Process). This method compares the criteria that must be fulfilled by the solutions and then calculates the best one. The results show that a lubrication-free solution would theoretically be preferable. This would be produced by a modern polymer and supplemented with an inner seal and an outer protection. Atlas Copco is recommended to test the various proposals to be able to decide which the best solution for the application is.
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Zhu, Shaocheng. „Contribution to the modeling of rolling element bearing – rotor system for railway application“. Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI136/document.
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Quelques développements sont démontrés dans cette thèse, du modèle de contact au modèle de roulement et du modèle de roulement-rotor à la technique de reproduction par bancs. Tout d’abord, la méthode de perturbation est étendue afin de prouver que la rigidité et l’amortissement distribués en état stable EHL ne remplissent pas les conditions transitoires et que les coefficients intégrés ne sont pas appropriés pour les analyses dynamiques. La loi de distribution de la rigidité et l’amortissement du film d’huile de l’EHL est proposée. En combinant l’état initial d’une solution stable avec l’amortissement et la rigidité distribués de l’EHL transitoire, les comportements du film d’huile peuvent être prédits. Par la suite, l’effet du contact en bordure entre le cylindre et le courant est pris en compte dans les transmissions de roulement. Les méthodes d’approximation première et seconde sont proposées pour interpréter numériquement cet effet. La méthode d’approximation première se concentre sur l’adoption de la méthode du coefficient d’influence pour reproduire l’effet de contact de même que l’utilisation du procédé de normalisation pour respecter les résultats empiriques ; alors que la méthode d’approximation seconde se concentre sur une manière analytique rapide de décrire la pression Hertz au contact entre le cylindre et le courant. Ensuite, les matrices de roulements pratiques sont utilisées pour développer un code de dynamiques 3D du roulement-rotor, basé sur des formules Hertz et EHL classiques. En temps-domaine, la méthode Adams quatre-ordres est améliorée pour résoudre les équations incrémentées des dynamiques non-linéaires. En fréquence-domaine, la méthode analytique de HB-AFT est particulièrement employée pour combler des matrices de roulement en 3D et des solutions d’état stable 3D. De plus, la méthode de continuation arc-longueur augmente la vitesse de calcul. En utilisant les deux méthodes, certains facteurs peuvent être considérés qualitativement et quantitativement, en incluant les états initiaux, l’amortissement, l’excentricité et les tensions internes et externes. Enfin, une technique alternative est proposée pour reproduire les comportements de contact à l’intérieur des roulements sous une forte charge et des vibrations à haute fréquence, lorsque les paramètres actifs sont en sous capacité du banc. Cette thèse apporte des visions nouvelles mais simples sur ce qui se produit sur les contacts roulants et longitudinaux d’un roulement circulaire ; sur comment modéliser et résoudre le système non-linéaire de roulement-rotor en domaines à la fois temps et fréquence ; et sur le moyen de reproduire des conditions de contact extrême à l’intérieur des roulementsSome developments on bearing applications are emphasized in this thesis, from contact model to bearing model, and from bearing-rotor model to bench reproduction technique. First, perturbation method is extended to prove that steady-state EHL distributed damping and stiffness do not satisfy the transient conditions, and steady-state EHL lumped coefficients are not suitable for dynamic analysis. Distribution law of EHL oil film damping and stiffness is attemptly proposed. Combining initial state of steady-state solution with transient EHL distributed stiffness and damping, dynamic behaviors of oil film are predicted. Second, edge effect of roller/race contact is considered in bearing transmissions. First and second approximation methods are proposed to numerically interpret this effect. First approximation method concentrates on adopting influence coefficient method to replay edge effect as well as using normalization process to respect empirical results, while second approximation method focuses on a fast-analytical manner of describing Hertz pressure inside roller slice. Third, practical bearing matrices are used to develop 3D bearing-rotor dynamics code, based on classical Hertz and EHL formulas. In time domain, four-order Adams method is improved to solve incremental nonlinear dynamics equations; In frequency domain, analytical method of HB-AFT is particularly employed to bridge 3D bearing matrices and 3D steady-state solutions, besides, arc-length continuation method increases calculation speed. Using both methods, some factors can be considered qualitatively and quantitatively, including initial states, damping, eccentricity, internal and external excitations. Last, an alternative technique is proposed to reproduce contact behaviors inside bearings under heavy loading and high-frequency vibrations, when working parameters are beyond bench capacity. This thesis gives new but simple insights into what happens to rolling and longitudinal contacts of bearing roller, how to model and solve nonlinear bearing-rotor system in both time and frequency domains, and where a way is to reproduce extreme contact conditions inside bearings using bench
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Kučera, Ondřej. „Realizace edukačních úloh na experimentálních stanicích pro kluzná ložiska mazaná olejem a vzduchem“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229016.
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This master thesis is focused to make education exercise on simulation equipment, tilting pad apparatus and air bearing apparatus. Exercise are, for better understanding problems, completed about exercise measurement viscosity. Were to be proposed three separate exercise for exercising, which were to be well – tried. Measured data from stations for sliding bearing will students confront with computed data. To every exercise are created instructions for exercising, educational presentation and poster to arrangement.
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Nguyễn, Thiết Lập. „Modélisation de l'interaction entre le coussinet et le corps de bielle“. Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2278/document.
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La tête de bielle n'est pas un solide mono-corps mais un solide multi-corps. Le serrage non-adapté des vis d'assemblage et les discontinuités des solides peuvent produire des phénomènes indésirables comme le glissement du coussinet dans son logement. Malgré des logiciels de calculs performants permettant de prédire le comportement des paliers il existe encore de nombreuses avaries notamment liées aux contacts entre le coussinet et son logement. La difficulté de la modélisation du contact coussinet/logement réside principalement dans l'interaction entre les différents solides et les conditions de fonctionnement. Cette étude propose une solution pour analyser ce problème par couplage entre un logiciel de calcul élatohydrodynamique (ACCEL) et un logiciel permettant le calcul du contact avec frottement entre les coussinets et le corps de bielle (ABAQUS). Après une étude bibliographique des études antérieures dédiées à la modélisation numérique et expérimentale des paliers de tête de bielle, la première partie est dédiée à une description des modèles numériques utilisés pour prédire le comportement élastohydrodynamique de paliers lubrifiés ainsi que les techniques employées pour étudier le contact sec avec frottement en mécanique. La deuxième partie présente la solution adoptée pour réaliser le couplage entre le logiciel ACCEL et le logiciel ABAQUS. Le modèle a été premièrement validée dans le cas d'un palier soumis une charge tournante. Par la suite, plusieurs calculs paramétriques, réalisés sur un cas type de palier de tête de bielle, nous ont permis de montrer l'influence des conditions de fonctionnement (diagramme de charge, vitesse de rotation, etc.) ainsi que d'autres caractéristiques de la bielle (coefficient de frottement, épaisseur du coussinet, etc) sur le comportement du palier et plus précisément sur le glissement relatif entre les coussinets et le corps de bielleThe connecting rod is not a single body but a multi-body solid. A non-appropriate screw tightening, coupled with the solid discontinuities, can lead to undesirable phenomena such as the rotation of the shell in its housing. Despite modern numerical tools, capable to predict the bearing EHD behaviour, there are still many damages related to cumulative microslip between the bearing shell and the conrod body. The difficulty of modelling the shell/conrod contact is mainly due to the interaction between the solids and the operating conditions. This study presents a solution to analyse this problem, by coupling an elastohydrodynamic (EHD) software (ACCEL) with a commercial software (ABAQUS) able to predict the frictional contact between the shell and the conrod. After a literature review of previous studies dedicated to the numerical and experimental modelling of connecting rod bearings, the first part is dedicated to a description of the numerical models used to predict the EHD behaviour of lubricated bearings. Follows the presentation of the techniques used to study the dry frictional contact mechanics. The next part presents the adopted solution used to couple the two software. The model was first validated in the case of a bearing submitted to a rotating load. Subsequently, several parametric calculations are presented. We were able to show the influence of the operating conditions (load diagram, velocity,...) as well as other characteristics of the conrod (friction coefficient, thickness of the shell, etc.) on the performances of the bearing and more exactly on the microslip between the shells and the conrod body
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Vincenc, Jan. „Laboratorní simulátor pro studium radiálních kluzných ložisek“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319274.
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The master’s thesis deals with a design of a radial journal bearing simulator, which is ready to implement a transparent sapphire journal bearing to an optical observation of the oil film. The first part of this thesis contains a short review of a few currently used journal bearing test rigs. The next part of the work deals with a discussion of concept variants and a definition of important parameters. The last part contains a detailed description of the designed radial journal bearing simulator. Limitations of the designed simulator and recommendations for future improvements are also discussed. The result of the presented work is the designed journal bearing simulator which will allow observing of the oil film. The work also consists a complete design documentation.
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Andharia, Paresh [Verfasser]. „Numerical modelling of certain problems of lubrication. The effect of transverse and longitudinal surface roughness on the performance of the bearing system / Paresh Andharia“. Munich : GRIN Verlag, 2016. http://d-nb.info/111226664X/34.
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Repka, Martin. „Research of Coatings of Hydrodynamically Lubricated Sliding Bearings for Combustion Engines“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-320204.
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Hlavní náplní této dizertační práce je výzkum a vývoj nové povrchové vrstvy pro kluzná ložiska na bázi pevných lubrikantů v polyamid-imidové polymerní matrici se zlepšenými tribologckými vlastnostmi. Podklady pro materiálovou kompozici vzešly z expertízy komerčně dostupného povlaku, respektive jeho povrchovou analýzou v mezných operačních podmínkách. Charakterizace mazného oleje před a po tribotestování společně s detailní povrchovou analýzou dala podmínky pro vznik materiálové formulace. Další část práce se zabývá studiem přípravy a vývojem aplikačního nanášení s přípravou polymerní směsi. Nakonec je popsána studie vlivu sulfidu molybdeničitého a grafitu, jakožto pevných lubrikantů pro zlepšení třecích vlastností a hydroxidu vápenatého pro potenciální zpepšení otěruvzdornosti výsledného povrchu pro palikaci kluzných ložisek.
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Daniel, Gregory Bregion 1984. „Analise dinamica de um sistema pino-pistão com lubrificação hidrodinamica“. [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263907.
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Orientador: Katia Lucchesi CavalcaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-12T19:28:08Z (GMT). No. of bitstreams: 1 Daniel_GregoryBregion_M.pdf: 2663262 bytes, checksum: f7c1b338ec3a0dad168c82dc8c8d2fc2 (MD5) Previous issue date: 2008
Resumo: Este trabalho visa analisar o comportamento dinâmico do sistema pino pistão. Por esse motivo, foi desenvolvido um modelo matemático para o mecanismo biela-manivela, considerando a influência do mancal hidrodinâmico da junção biela-pistão. As análises dinâmicas desse sistema foram realizadas utilizando dois modelos distintos. O primeiro modelo foi usado para representar o sistema quando o pino pistão está em contato com a superfície do mancal, assumindo, nesta condição, um comportamento similar aos mancais rígidos (sem folga). O segundo modelo foi empregado para representar o sistema quando o pino pistão está em lubrificação hidrodinâmica. Nesta condição, o pino pistão tem um movimento relativo à biela, o que torna este sistema um problema de múltiplos graus de liberdade. Diante disso, o primeiro modelo foi desenvolvido através da Equação de Movimento de Eksergian, sendo o segundo modelo, desenvolvido a partir do método de Lagrange. O modelo matemático de lubrificação hidrodinâmica foi introduzido com o intuito de obter resultados mais realísticos sobre o comportamento dinâmico do sistema. Este modelo de lubrificação considera as mesmas suposições básicas da teoria de lubrificação de Reynolds. A partir do modelo desenvolvido neste trabalho foram obtidas as orbitas do pino pistão, as distribuições de pressão e as velocidades e acelerações do mecanismo biela-manivela, o que permitiu realizar uma análise preliminar do comportamento dinâmico desse sistema.
Abstract: This work aims to analyze the dynamic behavior of the piston pin system. For this reason, a mathematical model for the slider-crank mechanism was developed, considering the influence of the hydrodynamic bearing of the piston-connecting rod joint. The dynamic analyses of the system applied two distinct models. The first represented the system when the piston pin was in contact with the bearing surface, assuming, in this condition, a similar behavior of rigid bearings (without clearance). The second model represented the system when the piston pin was in hydrodynamic lubrication. Under this condition, the piston pin presented a relative motion to the conrod, what turns this system into a multidegrees of freedom problem. Therefore, the first model was developed by Eksergian's Equation of Motion and the second model was developed by Lagrange method. The mathematical model of hydrodynamic lubrication was introduced to obtain more realistic results under the system's dynamic behavior. This lubrication model considers one of the basic assumptions of the Reynolds lubrication theory. From the model developed in this work were obtained the orbits of the piston pin, the pressure distributions and the velocities and accelerations of the slider-crank mechanism, what allows a preliminary analysis of the dynamic behavior of this system.
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
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Xie, Kebin. „Dimensioning of a cutter wheel bearings“. Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-80154.
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Mobile Miner 40V is a machine used for rock excavation and developed by Epiroc. This machine is equipped with a large cutter wheel to perform the excavation. After a test run, some surfaces associated with bearings within the cutter wheel were found to be damaged due to scuffing - severe sliding wear. There is a static load applied to the surfaces due to gravity. However, the reason for this damaged issue was believed that there is a large dynamic load applied to the surfaces during the excavation. This dynamic load was not found in a previous FE model used to verify safety issues. Therefore, a new FE model that is more in line with reality, and a failure analysis were required. Additionally, a feasibility study for a cutter wheel with a larger dimension was also needed since a larger cutter wheel is desirable. Firstly, wear mechanisms were reviewed, and some theories were chosen to analyze the damaged issue. Since it was unknown whether the surfaces were well-lubricated or not, both cases were investigated. The Archard wear equation was used to analyze the poor-lubricated situation, while the lubrication number and the Reynolds equation were used to analyze the well-lubricated case. Secondly, contact mechanisms between the surfaces were also investigated. The investigation of the contact mechanisms involved several theories, such as the Hertzian contact theory and the impact load factor. Besides these theoretical analyses, a numerical analysis was performed. Lastly, a new FE model was established in Ansys. Both the cutter wheel which was subjected to scuffing(existing cutter wheel), and the cutter wheel with a larger dimension(larger cutter wheel) were analyzed by the use of the new FE model. The maximum and minimum wear rates obtained by the Archard wear equation are approximately 1.9・10-2mm3/m and 4.8・10-3mm3/m, which are considered as a completely unacceptable level in engineering applications. The maximum and minimum critical loads obtained by the Reynold equation are approximately 1.8kN and 24.8kN, which both are larger than the static load applied to the surfaces. The maximum and minimum critical mean contact pressures obtained by the lubrication number are approximately 65MPa and 240MPa, which both are larger than the mean contact pressure generated by the static load. No evidence shows that there is a large dynamic load applied to the surfaces during the excavation. The largest possible contact pressure on the bearings in the existing cutter wheel is very close to the limit of severely damaged. The largest possible contact pressure on the bearings in the larger cutter wheel is believed to exceed the limit of severely damaged. The previous assumption that the surfaces were damaged due to a large dynamic load was wrong. The obtained results support that the surfaces were only subjected to a static load and were damaged due to inadequate lubrication. The existing cutter wheel is operated safely with the current load cases. However, the forward thrust force is suggested to decrease when the cutting angle is large. There is a high risk if the larger cutter wheel is operated with the current load cases.