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  • 101.
    Westerberg, Lars-Göran
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Li, Jinxia
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lugt, Piet
    SKF Engineering & Research Center, Nieuwegein.
    Baart, Pieter
    SKF Engineering & Research Center, Nieuwegein.
    Free-surface grease flow on a rotating plate2014Inngår i: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 56, nr 2, s. 317-325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Grease lubrication is traditionally used in a great variety of mechanical systems such as rolling bearings, seals, and gears where it has been shown more advantageous than oil, mainly due to its consistency allowing the grease to stay inside the system and not leak out. Knowledge of the flow dynamics of grease is important for the understanding and prediction of grease distribution for optimum lubrication and for the migration of wear and contaminant particles. Free-surface effects play an important role in rolling bearings and open gears as the configuration normally is filled with about 30 % grease to avoid heavy churning. In this study, an analytical model of the stationary uniform flow on a rotating disc is developed and validated with experiments. The model results in the velocity profile for the flow in the thin fully yielded viscous layer in connection to the surface as well as an expression for the plug flow region on top of the viscous layer. Furthermore, the depth-averaged velocity is derived as is the shear stress value on the plate. From the latter, follows a condition for the grease to start moving and in turn yielding an expression for the viscous layer thickness as a function of the grease yield stress value, grease density, angular velocity, and radial position. In addition, an expression of the layer thickness containing the ratio between the flow rate and the layer width which in turn can account for effects not included in the model such as wall slip and surface adhesion and thus add another degree of freedom into the model. Experiments with two different greases having NLGI grade 1 and 2, respectively, shows it is possible to obtain a good fit with the analytically obtained thickness using the rheological parameters for actual greases.

  • 102.
    Westerberg, Lars-Göran
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lugt, Piet
    SKF Engineering & Research Center, Nieuwegein.
    Investigation of grease flow in a rectangular channel including wall slip effects using microparticle image velocimetry2010Inngår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 53, nr 4, s. 600-609Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The grease flow in a rectangular channel is investigated using microparticle image velocimetry. Of certain interest is to study the behavior close to the boundary where wall slip effects are shown to be present. Three greases with different consistencies (NLGI00, NLGI1, and NLGI2) have been used, together with three wall materials (steel, brass, and polyamide) with different surface roughness. The pressure drop is also varied. It is shown that the velocity profile is strongly dependent on the consistency, having a dominating plug flow structure for a stiff grease. Furthermore, it is shown that wall slip effects occur in a thin shear layer close to the boundary where a very large velocity gradient is present. An analytical solution for the velocity across the channel is described using a Herschel-Bulkley rheology model. The model fits well with the measured velocity profile for all three above-mentioned greases.

  • 103.
    Westerberg, Lars-Göran
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, Staffan
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lugt, Piet
    Smörjfetters reologi: undersökning av randeffekter med μPIV2009Inngår i: Svenska mekanikdagarna: Södertälje 2009, Stockholm: Svenska nationalkommittén för mekanik , 2009, s. 68-Konferansepaper (Annet vitenskapelig)
  • 104.
    Westerberg, Lars-Göran
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, T. Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Green, Torbjörn
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Li, Jinxia
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lugt, Piet
    Baart, Pieter
    SKF Engineering & Research Center, Nieuwegein.
    Grease flow modeling using micro particle image velocimetry2013Inngår i: Svenska mekanikdagar 2013, Lund: Lunds tekniska högskola , 2013, s. 106-Konferansepaper (Fagfellevurdert)
  • 105.
    Westerberg, Lars-Göran
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Sarkar, Chiranjit
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Farré, Josep
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lubricating grease flow in a double restriction seal geometry: a Computational Fluid Dynamics approach2017Inngår i: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 65, nr 3, artikkel-id 82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, numerical simulations of lubricating grease flow in the grease pocket of a double restriction seal geometry using computational fluid dynamics are presented. The grease is treated as a single-phase Herschel–Bulkley fluid with different rheological properties corresponding to NLGI grade 00, 1 and 2. The numerical code and rheology model have been validated with a semi-analytical solution based on flow measurements using microparticle image velocimetry. The flow has been modelled for low and high rotational speeds driving the flow, and elevated temperatures. Also, the evolution of contaminant particles in the grease pocket is investigated. It was found that the flow and velocity distribution in the pocket—and consequently the contaminant particle concentration evolution, is characterized by the shear thinning rheology of the grease. With higher shear rates in the grease and higher temperatures, the grease approaches a more Newtonian type of behaviour leading to a reduced yield and shear thinning characteristics directly affecting the grease ability to transport contaminant particles.

  • 106.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Investigation of parameters affecting the limiting shear stress-pressure coefficient: a new model incorporating temperature1994Inngår i: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 116, nr 3, s. 612-620Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    When calculating film thickness and friction in elastohydrodynamically lubricated contacts, assuming a non-Newtonian fluid, the lubricant limiting shear stress is an essential parameter. It influences minimum film thickness and determines traction in the contact. The limiting shear stress is pressure dependent according to the Johnson and Tevaarwerk equation: τL = τ0 + γp The limiting shear stress-pressure coefficient γ has in a previous screening investigation been shown to depend on several parameters: oil type, oil viscosity at +40°C, maximum contact pressure and temperature. In the present investigation, the preliminary data is used together with response surface methodology. With these results in mind, further experiments are made and an empirical model is built. This paper presents a new model for γ which is valid for two types of oil (a polyalphaolefine with diester and a naphthenic oil) with different viscosities at +40°C. The model incorporates the influence of maximum contact pressure and oil temperature on γ. The measurements on which the model is based were carried out at temperatures ranging from -20 to +110°C. The pressure range was 5.8-7 GPa and the shear rate was about 106 s-1.

  • 107.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Starting and steady-state friction torque of grease-lubricated rolling element bearings at low temperatures: Part I: parameter study1996Inngår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 39, nr 3, s. 517-526Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experimental investigation of the friction torque in a roller element bearing was made. The aim was to sort out parameters important to bearing torque, and to see whether they interact. Friction torque in grease-lubricated bearings were compared to bearings lubricated with the corresponding base oil at - 20° and + 20°C. Also, base oil viscosity, NLGI number, load and acceleration at start-up were varied. No statistically significant difference was found between a grease and its corresponding base oil, independent of temperature, load or starting procedure and irrespective of which base oil that is considered. Most important to start-up torque was base oil viscosity. The effect was more pronounced at - 20°C at all combinations of the parameters. Running torque after a - 20°C start was not as dependent on type of base oil and base oil viscosity.

  • 108.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Starting and steady-state friction torque of grease-lubricated rolling element bearings at low temperatures. Part II: correlation with less-complex test methods1996Inngår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 39, nr 3, s. 684-690Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, torque measurements are conducted in full-scale test rigs, either standardized or specially designed. This is a time-consuming approach, especially at low temperatures, and it is therefore of high priority to find some less complex test method(s) correlating with bearing friction at different temperatures. The paper deals with five possible candidate test methods to predict low temperature starting and running friction: apparent viscosity, base oil viscosity, sliding friction, base oil traction properties and yield stress. The pros and cons of these methods are discussed and empirical expressions are presented for the methods where good correlation was found. It is stated that base oil viscosity at the temperature of interest is the best method to predict bearing friction torque at low temperature starting.

  • 109.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Wear of bearing liners at low speed rotation of shafts with contaminated oil1993Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 162-164, nr 2, s. 996-1001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experimental and theoretical investigation was carried out to investigate the relationship between wear of bearing liners and low shaft speed, contamination, oil temperature, bearing load and time. Experimentally, it was found that oil with no external debris added produced only slight polishing of the liners. When the oil was contaminated with 0.02 wt.% iron or quartz particles of a known distribution (less than 32 μm diameter), increased wear was detected. Also, comparison of the results of the clean and iron-contaminated tests with those for quartz-contaminated oil show that the character of the worn liner area has changed from evenly rubbed zones to equally divided polished stripes in the circumferential direction. During the tests, the bearing friction was measured. In no test did the friction rise drastically, as would have been the case if severe wear and scoring had appeared. In actual applications, though, this sometimes occurs. This may be explained by severe contamination in industrial lubricating systems, with larger particles and higher debris concentration. A clean lubricating system is thus crucial in order to avoid heavy wear at low speeds. The experimental results were then compared with those indicated theoretically for film thickness at low speed. The theoretical minimum film thickness at low speed was much smaller than the size of the debris. The results indicate that if So-1 <=340, B/D >=0.73 and C>=0.18 mm, no severe wear will occur.

  • 110.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Larsson, Roland
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    A theoretical analysis of shear stresses and roller slip in roller bearings during low-temperature starting1997Inngår i: Elastohydrodynamics -'96: fundamentals and applications in lubrication and traction : proceedings / [ed] D. Dowson, Amsterdam: Elsevier, 1997, s. 423-442Konferansepaper (Fagfellevurdert)
  • 111.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Östensen, Jan Ove
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Inverkan av låg temperatur på smorda maskinelement1995Rapport (Annet vitenskapelig)
  • 112.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Östensen, J.-O.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Friction torque and slip of rollers in roller bearings under arctic conditions1991Inngår i: Tezisy dokladov / Meždunarodnyj Sovetsko-Skandinavskij Seminar Mašiny, Materialy i Konstrukcii v Arktičeskich Uslovijach = Abstracts / International Soviet-Scandinavian Seminar Machines, Materials and Structures in Arctic Conditions, 1991Konferansepaper (Fagfellevurdert)
  • 113.
    Wikström, Victoria
    et al.
    Luleå tekniska universitet.
    Östensen, J.O.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Friction torque and slip of rollers in roller bearings under arctic conditions1990Inngår i: NORDTRIB'90: proceedings of the 4th Nordic Symposium on Tribology, Lubrication, Friction and Wear; 10th - 13th June 1990, Hirtshals, Denmark / [ed] Jørgen Jakobsen; Mads Klarskov; Michael Eis, Lyngby: NORDTRIB , 1990Konferansepaper (Fagfellevurdert)
  • 114. Åhrström, Bert-Olof
    et al.
    Lindqvist, S.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Sundin, Karl-Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Modified split Hopkinson pressure bar method for determination of the dilatation-pressure relationship of lubricants used in elastohydrodynamic lubrication2002Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 216, nr 2, s. 63-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In theoretical calculations of film thickness, pressure distribution and friction in an elastohydrodynamically lubricated (EHL) conjunction it is necessary to model the physical/mechanical behaviour of the lubricant. It is important to know, for example, the dilatation-pressure or the density-pressure relationship. In this paper a modified split Hopkinson pressure bar system for determination of the compressibility of oil is presented. It makes it possible to test oils under conditions similar to those found in real EHL contacts: loading duration in the range of 100-300 μs and pressures of almost 2 GPa. An empirical model has been suggested for mathematical description of the dilatation-pressure relation of the specific oils. A naphthenic mineral oil and a synthetic oil, 5P4E, have been tested under adiabatic conditions and at pressures up to 1.5 and 1.9 GPa respectively. The adiabatic results have been recalculated to isothermal conditions for comparison

  • 115.
    Åström, H.
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Rheological properties of lithium, lithium complex, and sodium greases1993Inngår i: Journal of Synthetic Lubrication, ISSN 0265-6582, Vol. 10, nr 3, s. 225-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The rheological properties of two lithium, two lithium complex, and two sodium greases, all with the most common NLGI grade two, have been investigated. The greases are based on a mineral and a synthetic oil. The apparatus used was a cone-and-plate rheometer and an impacting-ball apparatus. The impacting-ball apparatus used a steel ball, which impacted a lubricated sintered carbide plate, to measure the shear stress-pressure coefficient, γ, of the lubricant. At pressures found in elastohydrodynamic contacts this coefficient determined the limiting shear stress. The γ-value thus affects the coefficient of friction and consequently, lower γ-value means less friction. The results from the impacting-ball apparatus showed that γ-value was lower for the greases with a synthetic base oil and that the lithium greases gave a lower γ-value than the corresponding base oils. Results from the cone-and-plate rheometer showed the characteristic shear thinning behaviour of the greases and the influence of shear history and temperature. The results from the cond-and-plate rheometer have also been fitted to a four parameter rheological model.

  • 116. Åström, H.
    et al.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Rheological properties of lthium, lithium complex and sodium greases1990Inngår i: Nordtrib'90: proceedings of the 4th Nordic Symposium on Tribology, Lubrication, Friction and Wear : 10th-13th June 1990, Hirtshals, Denmark / [ed] Jørgen Jakobsen; Mads Klarskov; Michael Eis, Lyngby: NORDTRIB , 1990Konferansepaper (Fagfellevurdert)
  • 117.
    Åström, Henrik
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Inverkan av smörjfetters reologi och smörjförmåga på energiförluster i maskiner1991Rapport (Annet vitenskapelig)
  • 118.
    Åström, Henrik
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Rheological properties of six greases and their two base oils1990Rapport (Annet vitenskapelig)
  • 119.
    Åström, Henrik
    et al.
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Viewpoints on noise in grease lubricated bearings1994Inngår i: N L G I Spokesman, ISSN 0027-6782, Vol. 58, nr 4Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The noise level of a rolling element bearing is normally low, compared to the noise from the machine in which the bearing operates. Under certain circumstances, though, the noise caused by the bearing can be crucial and might influence the operation, for example, of very sensitive equipment. When lubricating rolling element bearings with grease, the noise level will depend upon the type of grease used. The relationship between structure and composition of lithium greases, and the noise they cause in rolling element bearings, is the subject of this paper. Different lithium greases have been studied in a model of the contact between ball and race in a bearing, using a ball and disc machine, as well as optical interferometry. The bearing noise levels have also been measured, using the same greases, and their microscopic structure studied, with the bearing noise level. Normal lithium greases cause disturbances in the model contact and also noise in a ball bearing. The noise level and the amount of disturbance is connected, with formations found in the microscopic grease structure. This technical paper can be obtained from the ELGI Office; see page 38 for ELGI address

  • 120.
    Åström, Henrik
    et al.
    Luleå tekniska universitet.
    Isaksson, Ove
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Video recordings of an EHD point contact lubricated with grease1991Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 24, nr 3, s. 179-184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optical interferometry has been used to study the film thickness of an EHD point contact lubricated with grease. The greases used were two lithium, two lithium complex and two sodium greases, all with NLGI grade two, the most common grade. They were based on one mineral oil of naphthenic type and one synthetic polyalphaolefin. The contact was lubricated without a continuous supply of grease and thus the film thickness decreased with time as the grease was gradually squeezed away from the contact area. The film thickness fluctuated during the measurement. To overcome this problem, the contact point was recorded with a video camera and the results evaluated after the tests. The video camera proved to be a powerful help in this evaluation. The tests were run at 20°C and under pure rolling conditions at a rolling velocity of 0.055 m s-1. The results from all greases showed a decreasing film thickness that tended to stabilize on about 0.2 μm after 40 cycles. The lithium and lithium complex greases showed strong local film thickness variations inside the lubricated contact, deviating from the normally horseshoe-shaped contact, during the first 20 to 40 cycles.

  • 121.
    Åström, Henrik
    et al.
    Luleå tekniska universitet.
    Östensen, Jan Ove
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Lubricating grease replenishment in an elastohydrodynamic point contact1993Inngår i: Journal of tribology, ISSN 0742-4787, E-ISSN 1528-8897, Vol. 115, nr 3, s. 501-506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A ball and disk apparatus was used to investigate the lubricant replenishment of an elastohydrodynamically lubricated point contact. This replenishment of the contact is crucial for building up a lubricating film. Whereas lubricating oil manages to achieve replenishment, lubricating grease appears not to achieve this, with lubricant starvation and a dramatic decrease in film thickness as a result. The distribution of grease around the contact was studied using normal and high-speed video. The movements of grease in the vicinity of the contact could be seen by adding molybdenum disulfide particles to the grease. A recording was then made, using high-speed video recording. The overall cavitation regions were studied using an ordinary video camera and grease without particles. On the basis of the results, possible lubricating grease replenishment mechanisms are discussed. The resulting film thickness was also compared with theoretical predictions using the Hamrock and Dowson starvation criterion, assuming negligible replenishment. The measured film thickness was larger than the predicted, which indicated that some replenishment occurs. In the case of an ordinary thrust ball bearing, replenishment was found to rely on the spin motion of the balls.

  • 122.
    Östensen, J.-O.
    et al.
    Luleå tekniska universitet.
    Wikström, Victoria
    Luleå tekniska universitet.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Interaction effects between temperature, pressure and type of base oil on lubricant shear strength coefficient1992Inngår i: Vol. 11, nr 2-4, s. 123-132Artikkel i tidsskrift (Fagfellevurdert)
  • 123. Östensen, J.O.
    et al.
    Åström, H.
    Höglund, Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Analysis of a grease-lubricated roller bearing under arctic conditions1995Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 209, nr 3, s. 213-220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper summarizes measurements of starting torque and motion of the rollers in a roller bearing during start-up at a temperature of -30 °C. The bearing was lubricated with three different greases and the tests were carried out after a running-in procedure at +20 °C. The results were compared with measurements obtained at +20 °C and with results from one base oil at +20 °C. A model for the roller motion was also built and simulations of the roller motion were compared with the measurements. Independent of temperature and lubricant the rollers rolled in the loaded zone and slipped, more or less, in the unloaded zone. The degree of sliding in the unloaded zone was found to be governed mainly by the local lubricant distribution and the position of the roller in the cage pocket. Some differences are also seen in the slide-roll ratio between the lubricants. A roller diameter difference of 1.3 μm gave a significant difference in roller motion, with the slightly thinner roller slides more in the unloaded zone of the bearing.

123 101 - 123 of 123
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