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  • 1.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Influence of gear surface roughness, lubricant viscosity and quality level on ISO 6336 calculation of surface durability2009Rapport (Övrigt vetenskapligt)
  • 2.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Influence of surface topography and lubricant design in gear contactsLicentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The purpose of this thesis was to study the influence of manufacturing variations on gear performance. The manufacturing variations inherent in different manufacturing methods were studied to include the effect of real surfaces. Real surfaces have surface irregularities at least on some scale, which can significantly influence how loads are transmitted at the gear contact. To some extent, the lubricant design can help to prevent contact that could lead to tooth failures by forming a protective surface boundary layer. An experimental study was used to consider the compositions of these layers with a surface analysis method.

    In Paper A a robust design approach was used to find out to what extent the current standard for calculation of surface durability treats manufacturing variations and the choice of lubricant. The results show that the simplest calculation method used is not enough to predict the effect of these on surface durability. Additionally, the standard quality levels are poorly incorporated in the standard calculating procedures for surface durability, and the quality of the gear tooth is restricted to include only a few parameters.

    In Paper B a pin-on-disc machine was used to evaluate the tribofilm formation by the additives and the corresponding wear occurring in the boundary lubrication regime in environmentally adapted lubricants. Studies of the additive and base fluid interaction were carried out using glow discharge-optical emission spectroscopy. It was found that the chemically reacted surface boundary layers played an important role in terms of wear. More specifically, the oxide layer thickness had significant influence on wear. The findings also demonstrate the complexity of lubrication design formulations coupled to these layers. For example, it was found that the pre-existing surface boundary layer (before any lubricant had been added) played an important role in allowing the lubricant to react properly with the surfaces.

    The aim of Paper C was to contribute to the knowledge of how different surface topographies, tied to manufacturing methods, influence the early life contact conditions in gears. Topographical measurements of differently manufactured tooth flanks were used as data input to a contact analysis program. The variation in surface topography inherent in the manufacturing method was found to have a strong influence on the contact area ratio.

  • 3.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    On tribological design in gear tooth contacts2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The correct tribological design will have a considerable effect on a gear’s service life and efficiency. The purpose of this thesis is to clarify the impact of variation in the gear tooth flank tribological system on the gear contact load capacity – to increase the understanding of how surface topography and lubricant interact.

    In this thesis the variation in surface topography inherent in the manufacturing method has been shown, by experimental work and computer simulations, to be an important factor for the contact condition in the early life of gears. Surface analysis revealed that the formation and composition of surface boundary layers depends strongly on the chemical composition of the lubricant, but also on pre-existing surface boundary layers. Additionally, surface boundary layers play a major role in frictional behaviour, wear and in allowing the lubricant to react properly with the surfaces.

    Paper A presents the current ISO 6336 calculation of surface durability. A robust design approach was used to investigate the extent to which the current standard for calculation of surface durability allows for manufacturing variations and the choice of lubricant.

    Paper B investigates the extent to which a logarithmical profile modification can increase gear contact pressure robustness compared to traditional lead profiles for gears.

    Paper C compares different gear manufacturing methods and their as-manufactured (fresh unworn) surface topographies, using measured surface topographies as input to a contact simulation program.

    Paper D examines surface boundary layer formation and the corresponding wear in relation to different anti-wear additives in an environmentally adapted base oil.

    Papers E and F make use of specimens with surface topographies imitating two gear manufacturing methods (grinding and superfinishing) to be used in a twin-disc and barrel-on-disc machine respectively. The contacts are analysed by friction measurements and simulations combined with methods for surface analysis.

  • 4.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Virtual Hobbing2007Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Hobbing is a widely used machining process to generate high precision external spur and helical gears. The life of thehob is determined by wear and other surface damage. In this report, a CAD approach is used to simulate the machiningprocess of a gear tooth slot. Incremental removal of material is achieved by identifying contact lines. The paper presentsan example of spur gear generation by means of an unworn and a worn hob. The two CAD-generated gear surfaces arecompared and showed form deviations.

  • 5.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Björklund, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Logarithmical Crowning for Spur Gears2010Ingår i: Strojniski vestnik, ISSN 0039-2480, Vol. 56, nr 4, s. 239-244Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gear tooth modifications, such as lead crowning, are often recommended to compensate for misalignment (e.g. assembly deviations). Lead crowning means that the tooth centre is slightly thicker than the tooth edges and is usually described as a circular arc profile. The use of crowning shifts the peak load from the tooth flank edges and, therefore, reduces the risk for high contact pressures at the edges, which can otherwise result in a shortened service life. In this study a logarithmical lead profile was compared with traditional lead profile modifications for gears. The profiles were applied on a spur gear pair and a numerical method for contact analysis was used to calculate the contact pressure distribution at the pitch diameter. All lead profiles were optimised with respect to low contact pressure at a specific normal load, a specified maximum misalignment in the plane of action and a tooth flank edge contact criteria. The results show that the logarithmical profile responds differently to misalignments compared to the traditional lead profile modifications. The logarithmical profile resulted in lower maximum contact pressures for small misalignments and is, therefore, of further interest in terms of achieving a robust gear design. (C) 2010 Journal of Mechanical Engineering. All rights reserved.

  • 6.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Henriksson, Mats
    Scania CV.
    Broukhiyan, Parsa
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sugutur, Lohith
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Nordin, Erland
    Scania CV.
    EFFECTS OF THRUST WASHER BEARING SURFACE CHARACTERISTICS ON PLANETARY GEAR TRAIN WEAR2017Konferensbidrag (Refereegranskat)
  • 7.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Henriksson, Mats
    Scania CV .
    Dizdar, Senad
    Höganäs AB.
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Effects of thrust washer bearing surface characteristics on planetary gear train wear2019Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 432-433, artikel-id 202933Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thrust washers in spur planetary gears are placed between the planet wheel and planet carrier and act as spacers and wear pads. Metal to metal sliding contact between the planet wheel – washer – carrier causes frictional power losses that, combined with starved lubrication, may cause high contact temperatures and thermo-mechanical effects that potentially trigger thermo-elastic instabilities and excessive local wear. The planetary gear system would benefit from a low-friction interface between the washer and the planet wheel. Five washers with different surface treatments were tested in a full-scale gear rig. These tests were also replicated as closely as possible in a pin-on-disc tribometer. The following types of finishing material treatments were studied: a chemical nickel coating plus polymer on a nitro-carburised surface, a combination of nitro-carburization and solid lubricant layers, electroless deposited chemical nickel coating plus polymer, nitro-carburizing, and manganese phosphating. The frictional results indicate that tribometer tests can be used to compare and classify new washer materials. Lab scale tests show that a new experimental self-lubricating tribomaterial that was applied with laser cladding has a promising potential to increase planetary gear train robustness and service life, especially if the surface is fine grinded.

  • 8.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Höjer, Martin
    Tyréns AB, Stockholm, Sweden.
    Lyu, Yezhe
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Nilsson, Rickard
    Stockholm County Council, Traffic Administration, Stockholm, Sweden.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    A Wear Detection Parameter for the Wheel–Rail Contact Based on Emitted Noise2019Ingår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 62, nr 3, s. 496-503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article describes how a wheel–rail wear detection parameter based on noise was developed by running a rapid transit train instrumented with microphones in a depot with a small curve radius. This full-scale test made use of previous knowledge gained from lab-scale tests. The lab- and full-scale tests showed that noise could be used as an indicator of wear transition, when normal wear turns into severe or catastrophic wear. This transition was accompanied by a significant increase in sound pressure and a broader sound pressure amplitude spectrum; that is, a narrow initial amplitude distribution in the normal wear regime and a broader distribution in the severe wear regime. The measured noise from the inner/low and outer/high rails was analyzed in conjunction with the wear from the outer wheel and comparisons were made between cleaned (exposed to severe wear) and lubricated (no wear) rail. Based on those analyses, a wear detection parameter criterion was developed for this specific train. This wear parameter has been implemented in a real-time condition monitoring system so that warnings of the risk for severe wear could be sent to the maintenance department. Validation of the wear parameter and challenges linked to open system conditions are discussed in this article.

  • 9.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Olofsson, U
    Lewis, R
    Lewis, S
    Effect of gear surface and lubricant interaction on mild wear2010Konferensbidrag (Refereegranskat)
  • 10.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Andersson, Martin
    Sosa, Mario
    EXPERIENCES OF STUDYING GEAR TRIBOLOGY IN A FZG TEST SET-UP2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main objective of this study is to review the last decade of experimental work in the field of gear pitting life andefficiency of an FZG gear test rig. Located at KTH Machine Design, the FZG rig has led to critical findings with an impacton gear transmissions, such as high efficiency and long fatigue life. The different FZG test set-ups, the sampling methodsand the results (and their limitations) are discussed, and measures are proposed to reduce the limitations. The findingsof this study are used as input to an impact case on how research at a university can provide the major transportindustry in Sweden with the knowledge and the methods to evaluate gear performance.

  • 11.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Lewis, Roger
    Sheffield University, UK.
    Lewis, Stephen
    Sheffield University, UK.
    Effect of Gear Surface and Lubricant Interaction on Mild Wear2012Ingår i: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 48, nr 2, s. 183-200Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, a twin-disc test machine was used to simulate a rolling/sliding gear contact for three surface finishes, each run with two types of lubricants, thus seeking to develop insight into the tooth flank/lubricant tribological system. The test disc surfaces were case-carburised before the surfaces were produced by: transverse grinding followed by a mechanical abrasive polishing process; transverse grinding only; and transverse grinding followed by preheating as a final finishing step (intended to enhance the build-up of an easily sheared surface boundary layer using a sulphur additive). The twin-disc contact was lubricated with an ester-based environmentally adapted lubricant or a polyalphaolefin-based commercial heavy truck gearbox lubricant. To obtain information about the composition of chemically reacted surface layers, the specimens used were analysed using glow discharge-optical emission spectroscopy. The results indicate that the interactions between different surface finishes and lubricants have different impacts on friction behaviour, wear and the reacted surface boundary layer formed by the lubricant. Running a smooth (polished) surface with the appropriate lubricant drastically reduces the friction. Surface analysis of the ground surfaces gives clear differences in lubricant characteristics. The commercial lubricant does not seem to react chemically with the surface to the same extent as the EAL does. Micropitting was found on all ground discs with both lubricants, though at different rates. The highest amount of wear but less surface damage (i.e. micropits) was found on the preheated surface run with the commercial lubricant.

  • 12.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Sjöberg, Sören
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Björklund, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Influence of real surface topography on the contact area ratio in differently manufactured spur gears2012Ingår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 56, s. 72-80Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface topography measurements from spur gears produced using four different manufacturing methods were used as input to a contact analysis programme. All test gears were case-hardened, two gears were machined in the hardened state using honing and grinding respectively, and two gears were machined in the non-hardened state using hobbing and hobbing followed by green-shaving respectively. The results show that the surface topography caused by the manufacturing methods has a large influence on the real contact area in the early life of the gear. The green-shaved gear surfaces and the honed gear surfaces have the highest contact area ratio after manufacturing (as-manufactured), which could be advantageous for future gear life with respect to e.g. the running-in process.

  • 13.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Sosa, Mario
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Andersson, Martin
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    A note on the pitting life of IQ steel versus 16MnCr5 steel in a back to back gear test rig2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    IQ-steel is isotropic (i.e. equally strong in all directions), cleaner, and with less inclusions than 16MnCr5 regular gear steel (RS). IQ-steel is used in diesel inlets and for bearings but to date has not been used for gears. Previous studies, has shown good potential to increase the bending fatigue life of gears. The method in this study is a mechanical test procedure to determine the pitting load capacity of gear transmission lubricants, but with the focus on comparing the pitting load capacity of the two steel types IQ-steel with RS. Times to failures, photographs of the fatigue damage are presented in the study. Gear teeth from each steel type were analysed using SEM. The results, which are based on six tests in total (three IQ-steel and three RS-steel gear pairs), indicate that the IQ-steel may have at least similar surface capacity as the regular steel.

    Keywords: Pitting life, Gear, IQ-steel

  • 14.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Sosa, Mario
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Andersson, Martin
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Investigation of pitting resistance in ultra clean IQ-Steel vs commonly used conventional steel; 158Q vs 16MnCr5: Back-to-back pitting tests2015Rapport (Övrigt vetenskapligt)
    Abstract [en]

    KTH Machine Design has conducted pitting tests on gears made out of two different types of steel in a standard back-to-back pitting test rig (FZG). The tested gears were produced from Ovako’s IQ-Steel in grade 158Q and compared to the behaviour of a reference steel, commonly used conventional steel in grade 16MnCr5 (reference steel, RS). The test method is a mechanical test procedure generally used to determine the pitting load capacity of gear transmission lubricants, but in this study the purpose was to compare the pitting load capacity of the two steel types. The report is based on the test procedure described in FVA – Information sheet Research Project No. 371 (Practice Relevant Pitting Test) with minor changes. Time to failure and photographs of the fatigue damages are presented in this report. One gear tooth from each steel type was analysed using SEM. The results, which are based on six tests in total (three gear pairs IQ-Steel and three RS-steel), indicate that the IQ-Steel has better surface durability than the reference steel. To better understand the mechanisms involved, further tests are suggested.

  • 15.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Söderberg, Anders
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Zhu, Yi
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Study of surface roughness and surface orientation on friction in rolling/sliding contacts: barrel-on-disc versus twin-disc2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Gears are one of the most important means of mechanical power transmission. Even though the efficiency is high for a gear pair today, further decrease in friction can contribute to lower the fuel consumption. A barrel-on-disc machine (same setup as ball-on-disc) to simulate a rolling/sliding gear contact was used to study the impact of manufacturing method, grinding and superfinishing, on friction. To evaluate the extent to which friction and wear can be diminished by reducing surface roughness and changing surface orientation. Measurement results showed that the change of lubricant had an impact on friction in the mixed to boundary lubrication regimes similar to that of the change of main surface orientation. The results were compared with those from a parallel study involving a twin-disc machine, also used to simulate rolling/sliding contacts (see Figure). Measurements and simulations showed that the barrel-on-disc and twin-disc setups reflected the same friction trends. However, the friction coefficient using the barrel-on-disc setup was almost twice as large as that found using the twin-disc machine. The wear mechanisms also differed: micropits occurred on discs used in the twin-disc set-up whereas normal or no wear was found on the barrel-on-disc specimens. The difference in contact geometry is believed to be the main reason for the higher friction level in the barrel-on-disc machine. A computer contact analysis was used to clarify the differences using perfectly smooth and computer-generated textured surfaces.

  • 16.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Torbacke, M.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Wear in environmentally adapted lubricants with AW technology2008Ingår i: Journal of Synthetic Lubrication, ISSN 1557-6841, Vol. 25, nr 4, s. 137-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of the study was to examine the tribofilm formation and the corresponding wear occurring in the boundary lubrication regime in environmentally adapted lubricants, i.e. when using synthetic ester base fluids with different anti-wear additives. AW additives of the following types were studied: phosphorus, sulphur–phosphorus and sulphur–nitrogen together with an additive based on carbon, hydrogen, oxygen and nitrogen chemistry. In addition, the base fluid itself was tested.Wear was studied in a pin-on-disc-machine giving the wear coefficient. The surfaces were analysed by glow discharge-optical emission spectroscopy, revealing the surface reactions formed by the additives. The results indicate that the wear number decreases with increasing reacted surface layer depth as well as with increasing oxide layer depth. Also, the results indicate that a highly polar base fluid give relatively low wear numbers even without additives.

  • 17.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Torbacke, M.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Wear in environmentally adapted lubricants with AW/EP technology2008Ingår i: Tech. Akad. Esslingen Int. Tribol. Colloq. Proc., 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mineral oil based lubricants are dominating the market still. However, there is now a broad range of environmentally adapted lubricants (EAL) based on both natural and synthetic esters. Wear was studied in a pin-on-disc-machine giving the wear coefficient. The surface reactions formed by the additives were examined. The studied lubricants were formulated with a complex ester as the base fluid. The wear number decreased with increasing reacted surface layer depth as well as with increasing oxide layer. A highly polar base fluid gave relatively low wear numbers even without additives. This is an abstract of a paper presented at the 16th International Colloquium Tribology Lubricants Materials and Lubrication Engineering (Stuttgart/Ostfildern, Germany 1/15-17/2008).

  • 18.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Zhu, Yi
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Study of surface roughness and surface orientation onfriction in rolling/sliding contacts: barrel-on-disc versustwin-discManuskript (preprint) (Övrigt vetenskapligt)
  • 19. Höjer, M.
    et al.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Nilsson, R.
    Lyu, Yezhe
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    A noise related track maintenance tool for severe wear detection of wheel-rail contact2016Ingår i: Civil-Comp Proceedings, ISSN 1759-3433, Vol. 110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An on-board measurement system has been developed that in real time identifies the probability for occurrence and also the exact location of severe wear in the wheelrail contact. Noise generated by the wheel-rail contact is a troublesome side effect both when railway vehicles negotiate curves and run on straight tracks. The concept behind this project is to use this noise as an indicator of the transition from the mild wear regime to the severe/catastrophic wear regime that implies high maintenance cost. At first tribometers were used in a laboratory study to investigate the relationships between wear and the emitted noise. Wear transitions from mild to severe wear were always accompanied by an increase in sound pressure of about 10 dB. The transitions also changed the sound pressure amplitude distribution from a narrow banded to a broader banded distribution. Secondly a full scale test in a small radius curve in a depot was carried out using a metro train, type C20. In agreement with the laboratory tests, the same kind of transfer from mild to severe wear was identified on the full scale tests in the depot. In addition, the sound pressure changed significantly, both in amplitude and in distribution, when transferring from mild to severe wear. By comparing the noise from the inner wheel-rail contact to noise from the outer wheel-rail contact a wear detection parameter for the outer wheel-rail contact is suggested. The third part of this project involves validation of the maintenance tool by operating the instrumented train in normal metro traffic, while at the same time collecting wear particles and making replicate casts of the rail at critical locations in the metro. Further comparison with weather data and a maintenance log has also been performed. © Civil-Comp Press, 2016.

  • 20.
    Li, Xinmin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Pin-on-Disc Study of Tribological Performance of Standard and Sintered Gear Materials Treated with Triboconditioning Process: Pre-treatment by Pressure-induced Tribo-film formation2017Ingår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 60, nr 1, s. 47-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    oating is one of the innovative approaches used to improve the wear resistance and load-carrying capacity of surfaces in rolling-sliding contact, such as gears and rolling element bearings. In this study, the tribological performance of standard gear material (16MnCr5) and two kinds of powder metallurgy (PM) gear material (Distaloy AQ + 0.2% C and Astoloy 85Mo +0.2% C) with and without tribofilms formed by a pre-treatment were evaluated. Specimens treated with the pre-treatment and the substrate is subjected to pin-on-disc tests under boundary lubrication conditions. The friction and wear performance of the two different PM gear materials with the pre-treatment formed tribo-film were compared to RS-RS (16MnCr5 material disc and pin combination) for reference. It was found that the pre-treatment lowers the friction coefficient and enhances the wear resistance of pins because of the tribo-film formed. The tribo-film caused good running-in due to the existing of  and Fe and W oxides. Mo-Mo (Astoloy 85Mo + 0.2% C material disc and pin combination) and Mo-RS (Astoloy 85Mo + 0.2% C disc and 16MnCr5 pin combination) showed statistically significant higher wear resistance.

  • 21.
    Lyu, Yezhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Open System Tribology and Influence of Weather Condition2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 32455Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The tribology of an open system at temperatures ranging between 3 degrees C and -35 degrees C, with and without snow, was investigated using a pin-on-disc tribometer mounted in a temperature-controlled environmental chamber. The relationship between the microstructure and ductility of the materials and the tribology at the contacting surfaces was investigated. The study shows that during continuous sliding, pressure causes snow particles to melt into a liquid-like layer, encouraging the generation of oxide flakes on the contact path. The friction coefficient and wear rate are dramatically reduced through an oxidative friction and wear mechanism. In the absence of snow, the tribological process is controlled by the low temperature brittleness of steel in the temperature range from 3 degrees C to -15 degrees C. At these temperatures, cracks are prone to form and extend on the worn surfaces, resulting in the spalling of bulk scraps, which are crushed into debris that increases the friction coefficient and wear rate due to strong abrasion. When the temperature falls to -25 degrees C, an ice layer condenses on the metal surfaces and relaxes the tribological process in the same way as the added snow particles, which significantly decreases the friction and wear.

  • 22.
    Lyu, Yezhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    The effect of Subzero temperature and snow on the tribology of wheel-rail contact2016Ingår i: Civil-Comp Proceedings, ISSN 1759-3433, Vol. 110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wheel-rail system operates in an open environment where the weather condition varies constantly. In this laboratory study, an investigation using a pin-on-disc tribometer placed in a temperature-controlled room was conducted to examine the effect of subzero temperature and snow on friction and wear at the wheel-rail contact. In temperature range from 3 to-15 °C (without snow) friction and wear were dominated by low temperature brittleness, which led to an increase in friction and wear. When temperature decreased down to-25 °C, an ice layer condensed on the pin and disc surfaces, which then melted during sliding and acted as a lubricant, leading to the sharp decrease of friction and wear. When snow crystals were added into the contact they melted into water droplets during sliding because of pressure melting and reduced the friction and wear following the boundary lubrication mechanism. With increasing temperature from-25 to 3 °C, friction performed monotonously decreasing because of the increasing thickness of the water layer. A large area of oxide flakes generated on the worn surfaces also significantly protected the contacting wheels and rails from severe wear. © Civil-Comp Press, 2016.

  • 23.
    Lyu, Yezhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    TRIBOLOGY OF THREE RAILWAY BRAKE BLOCK MATERIALS TESTED AGAINST RAILWAYWHEEL AT LOW TEMPERATURES2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Three railway brake block materials, i.e. cast iron, sintered and organic composite, were tested against railway wheel at10, 3, -10, -20 and -30 °C using a pin-on-disc tribometer with regards to the friction and wear performance. At -10 and -20 °C, cast iron tests yielded very high wear losses both on pin and disc samples and low friction coefficient. The largeamount of graphite worn off from the cast iron sample acted as a lubricant. Friction and wear of sintered material arenot sensitive to the change of temperature. Disc sample tested against organic composite at -30 °C showed negativewear loss, indicating that materials were added onto the surface.

  • 24.
    Lyu, Yezhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Lindgren, Anders
    Tyréns AB, Stockholm, Sweden.
    Höjer, Martin
    Tyréns AB, Sweden.
    On the relationships among wheel–rail surface topography, interface noise and tribological transitions2015Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 338-339, s. 36-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Noise from the wheel-rail interface is a troublesome side effect when railway vehicles negotiate rail curves and straight tracks. A laboratory study using two pin-on-disc tribometers to simulate the pure sliding process in a wheel-rail contact investigated the relationships between surface topographies, tribological aspects and emitted noise. The influence of five different initial surface topographies manufactured by polishing and grinding (transverse and circular) was studied. Polished samples yielded the highest friction coefficient and wear rate because of strong adhesion. Samples with manufacturing traces vertical to the sliding direction produced the lowest friction coefficient and wear rate, and were dominated by ploughing and abrasion. Samples with manufacturing marks parallel to the sliding direction exhibited a medium level in both fiction coefficient and wear rate; the wear mechanism was combined ploughing-adhesion. Noise emission followed the same pattern as the friction coefficients: the highest sound pressure levels occurred for the polished samples and the lowest for the samples with transverse manufacturing marks. Wear transitions from mild to severe wear were always accompanied by an increase in sound pressure of about 10 dB. The transitions also changed the sound pressure amplitude distribution from a narrow banded to a broader banded. 

  • 25.
    Lyu, Yezhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Wahlström, Jens
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    A pin-on-disc study on the tribology of cast iron, sinter and composite railway brake blocks at low temperatures2019Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, s. 48-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Most freight wagons in the EU use cast iron brake blocks. Cast iron brake blocks have a stable braking capability in different environmental conditions, but wear down the wheel tread quickly. Therefore, there is a need to understand the tribology of other brake block materials. A pin-on-disc tribometer placed in a temperature-controlled chamber is used to investigate the tribology of cast iron, sinter and composite railway brake blocks at low ambient temperatures. Pins made from different brake blocks are tested with discs made from steel wheels. Both friction coefficient and wear are evaluated at five different temperatures from + 10 to − 30 °C. The cast iron block demonstrated the greatest wear at − 10 and − 20 °C, due to the ductile-to-brittle transition at low temperatures. The worn graphite from cast iron is likely to become a solid lubricant, reducing the friction at − 10 and − 20 °C. For the composite brake block, a gradual decrease in friction with decreasing temperature was found. The sinter brake block was not sensitive to changes in ambient temperature. The sliding speed in the current study is relatively low and further study at higher speed is suggested in order to evaluate the tribological performance of different brake blocks.

  • 26.
    Lyu, Yezhe
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Björklund, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Nilsson, R.
    Lindgren, A.
    Höjer, M.
    Development of a noise related track maintenance tool2015Ingår i: 22nd International Congress on Sound and Vibration, ICSV 2015, International Institute of Acoustics and Vibrations , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    The purpose of this work-package within the Quiet-track, FP7, is to develop a noise related track maintenance tool, in the form of an on-board measurement system. As a first step, lab scale tests using a pin-on-disc tribometer were used in order to distinguish how noise changes when the wear mechanism in a sliding contact shifts from normal wear to severe and catastrophic wear. Once the potential for using sound as an indication of severe wear transitions was established, full scale tests were carried out with a rapid transit (metro) train, type C20. The train was equipped with microphones that continuously measured the sound pressure near the wheel rail contact. In order to provoke severe/catastrophic wear, the test train was run in a curve with small radius, and the rails and wheels were carefully cleaned before the tests. The same kind of transfer from mild to severe/catastrophic wear was identified on the full scale test as in the laboratory scale test, confirmed by studying the surface topography and the morphology of the wear particles. Moreover, the full scale test results showed that the sound pressure changed significantly when transferring from mild to severe wear in agreement with the pin-on-disc test results. By comparing noise from the inner wheel/rail contact to noise form the outer wheel/rail contact a wear indication value for the outer wheel/rail contact is suggested in this study. This value can be seen as an advanced parameter from which the probability of severe wear, in the wheel flange/rail gauge face contact of the outer contact, can be estimated. At present, a real time condition monitoring system is set up in Stockholm (Metro line 1) in order to validate the results.

  • 27.
    Mahmood Reza, Khabbazi
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Wikander, Jan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Maffei, Antonio
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Onori, Mauro
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Assembly Feature Data Instance Modeling: Prototype Implementation and Outputs2017Ingår i: 2017 INTERNATIONAL CONFERENCE ON MECHANICAL, SYSTEM AND CONTROL ENGINEERING (ICMSC), IEEE , 2017, s. 343-347Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper introduces the assembly feature data schema instance modeling to pre-examine the schema functionality and output- as the preliminary step for data modeling. In order to link assembly with product design, it is essential to determine which entities of product design are involved at the automated assembly planning and operations. It is possible to assign meaningful attributes (assembly features) to the part model entities in a systematic and structured way. Using object-oriented design, the assembly feature data structure and its relationships are modeled. As a part of the research on product and assembly system data integration within the evolvable production system platform, the instance models for proposed assembly feature data structure provide a deeper understanding and error reduction that might possibly occur at the development of the database. Moreover through instance modeling, the assembly feature data query output format from the database prototype is simulated. An industrial assembly model example with its 3DPart models is chosen to demonstrate the realized assembly feature data set with string data type. The models support the desired simplicity at the database prototype implementation. The output format envisions the interoperability factor between product models and the assembly planning systems.

  • 28.
    Sjöberg, Sören
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Björklund, Stefan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Influence of real surface topography on the contact area ratio in differently manufactured spur gears2008Ingår i: Proceedings of Tribology 2008: Surface Engineering of Automotive Powertrains for Environmentally Friendly Transport, 2008Konferensbidrag (Refereegranskat)
1 - 28 av 28
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