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Fatima, Nowshir
Publikasjoner (10 av 12) Visa alla publikasjoner
Fatima, N., Minami, I., Holmgren, A., Marklund, P. & Larsson, R. (2016). Surface chemistry of wet clutch influenced by water contamination in automatic transmission fluids (ed.). Paper presented at . Tribology International, 96, 395-401
Åpne denne publikasjonen i ny fane eller vindu >>Surface chemistry of wet clutch influenced by water contamination in automatic transmission fluids
Vise andre…
2016 (engelsk)Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 96, s. 395-401Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Lubricated friction interfaces used for wet clutches produces different friction behaviour depending on the lubricant conditions. Usually the lubricant conditions vary for water contamination in automatic transmission fluid (ATF). The presence of water retards the ATF performance by increasing the friction and can influence the deterioration of the clutch plates. Water as a polar contaminant can change the absorbability of the surface active additives, which might cause the characteristic friction behaviour. The aim of this paper is to verify the surface chemistry of tribotested standard friction interfaces lubricated with water contaminated commercial ATF (DEXRON® VI). The evidences of the influence of water on ATF performances were shown by surface analyses

HSV kategori
Forskningsprogram
Maskinelement; Kemisk teknologi
Identifikatorer
urn:nbn:se:ltu:diva-12875 (URN)10.1016/j.triboint.2015.04.010 (DOI)000371100800037 ()2-s2.0-84959268273 (Scopus ID)c061d8b7-8d03-4a56-bb26-b1b4edd96239 (Lokal ID)c061d8b7-8d03-4a56-bb26-b1b4edd96239 (Arkivnummer)c061d8b7-8d03-4a56-bb26-b1b4edd96239 (OAI)
Merknad
Validerad; 2016; Nivå 2; 20150416 (andbra)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Fatima, N., Marklund, P., Mathew, A. P. & Larsson, R. (2016). Wet Clutch Friction Interfaces under Water Contaminated Lubricant Conditions (ed.). Tribology Transactions, 59(3), 441-450
Åpne denne publikasjonen i ny fane eller vindu >>Wet Clutch Friction Interfaces under Water Contaminated Lubricant Conditions
2016 (engelsk)Inngår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 59, nr 3, s. 441-450Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The performance of wet clutches used for automatic transmissions or other applications usually includes the desired positive friction characteristics and a shudder-free torque generation. Changes in the operating variables such as the lubricant conditions influence the formation of tribofilm, friction characteristics and can alter the degradation of the friction interfaces. In this work, the friction characteristics and degradation of the paper-steel friction interfaces were monitored when a commercial fully-formulated automatic transmission fluid (ATF) was contaminated with water. It was found that water in ATF influenced the clutch stability by increasing the mean coefficient of friction (µ) and the negative friction-velocity slope. Surface studies of the post-test friction interfaces clearly indicated reduced surface porosity and permeability, increased wettability and changed elemental composition on the contacting surfaces after tested with water- contaminated ATF. Moreover, water-contaminated paper-liners’ thermal decomposition shifted to a lower temperature compared to an uncontaminated liner during thermal analyses. These results displayed faster degradation and reduced service life of the clutch friction interfaces for water contamination. The resultant surface condition can be associated with the observed unstable friction and negative friction-velocity slopes.

HSV kategori
Forskningsprogram
Maskinelement; Trä och bionanokompositer
Identifikatorer
urn:nbn:se:ltu:diva-9929 (URN)10.1080/10402004.2015.1081998 (DOI)000379702000007 ()2-s2.0-84975521420 (Scopus ID)8a320fba-e6e8-460d-be12-1c4d7252fe12 (Lokal ID)8a320fba-e6e8-460d-be12-1c4d7252fe12 (Arkivnummer)8a320fba-e6e8-460d-be12-1c4d7252fe12 (OAI)
Merknad

Validerad; 2016; Nivå 2; 20160408 (andbra)

Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Fatima, N., Holmgren, A., Marklund, P., Minami, I. & Larsson, R. (2015). Degradation Mechanism of Automatic Transmission Fluid by Water as a Contaminant (ed.). Paper presented at . Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, 229(1), 74-85
Åpne denne publikasjonen i ny fane eller vindu >>Degradation Mechanism of Automatic Transmission Fluid by Water as a Contaminant
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2015 (engelsk)Inngår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 229, nr 1, s. 74-85Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The degradation mechanism of water contaminated Automatic Transmission Fluids (ATF) was experimentally investigated. Water contaminated ATF was tribotested in a full-scale wet clutch test rig to monitor the friction durability during clutch ageing, and was also statically aged in oven to evaluate the interaction of ATF with water. The bulk properties and chemical nature of the ATF were analysed using viscosity measurements, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). It was shown that water presence in the ATF can increase the mean friction coefficient over a short time period, though in the long term perspective there is a higher loss of mean friction. Phase separation of the water-in-oil emulsion by centrifugation at 20000 rpm made it possible to examine the water phase using infrared 2spectroscopy. The spectroscopic analysis revealed the hydrophilic nature of certain ATF constituents, although the impact of water on the bulk properties like lubricant viscosity and thermal stability was insignificant. The analysis of the tribotests showed that the friction increase for water contamination was a short-term effect and likely due to the interaction between polar surface active additives and water. Even though no significant change has been found for thermal degradation or in bulk properties of the lubricant, the initially changed action of the water soluble additives and generation of high friction resulted in a total deterioration of the clutch performance during long term use.

HSV kategori
Forskningsprogram
Maskinelement; Kemisk teknologi
Identifikatorer
urn:nbn:se:ltu:diva-3400 (URN)10.1177/1350650114542477 (DOI)000346255500005 ()2-s2.0-84919343321 (Scopus ID)139d32b2-daff-413c-be5d-f1c1a01df1d6 (Lokal ID)139d32b2-daff-413c-be5d-f1c1a01df1d6 (Arkivnummer)139d32b2-daff-413c-be5d-f1c1a01df1d6 (OAI)
Merknad
Validerad; 2014; Nivå 2; 20140619 (nowfat)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Fatima, N., Minami, I., Holmgren, A., Marklund, P., Berglund, K. & Larsson, R. (2015). Influence of water on the tribological properties of zinc dialkyl-dithiophosphate and over-based calcium sulfonate additives in wet clutch contacts (ed.). Paper presented at . Tribology International, 87, 113-120
Åpne denne publikasjonen i ny fane eller vindu >>Influence of water on the tribological properties of zinc dialkyl-dithiophosphate and over-based calcium sulfonate additives in wet clutch contacts
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2015 (engelsk)Inngår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 87, s. 113-120Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Usually the wet clutch lubricant properties vary with different formulations of base oil types and additives. The aim of this paper was to evaluate the effect of water on the performance of additives in ATF. Simplified lubricants, ZDDP and over-based Ca-sulfonates detergent additives in an API Group I mineral base oil, were employed to compare with the commercial fully-formulated automatic transmission fluid (DEXRON®VI) during water-contamination. A full-scale wet clutch test rig was used to evaluate the frictional response due to water contamination of the lubricants. Fourier Transform Infrared Spectroscopy was utilized to evaluate the variation in the solubility of these polar organic additives in the water phase and Karl-Fischer titration was utilized to evaluate the post-test water content for different formulations.

HSV kategori
Forskningsprogram
Maskinelement; Kemisk teknologi
Identifikatorer
urn:nbn:se:ltu:diva-13289 (URN)10.1016/j.triboint.2015.02.006 (DOI)000353730500013 ()2-s2.0-84924913600 (Scopus ID)c7d39d15-0ec2-4a97-b3fa-72d8755bdd6a (Lokal ID)c7d39d15-0ec2-4a97-b3fa-72d8755bdd6a (Arkivnummer)c7d39d15-0ec2-4a97-b3fa-72d8755bdd6a (OAI)
Merknad
Validerad; 2015; Nivå 2; 20150213 (andbra)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Fatima, N., Minami, I., Holmgren, A., Marklund, P. & Larsson, R. (2014). Adsorption of ATF additives on wet clutch friction interfaces under water contaminated lubricant conditions (ed.). Paper presented at Nordic Symposium on Tribology : 10/06/2014 - 13/06/2014. Paper presented at Nordic Symposium on Tribology : 10/06/2014 - 13/06/2014.
Åpne denne publikasjonen i ny fane eller vindu >>Adsorption of ATF additives on wet clutch friction interfaces under water contaminated lubricant conditions
Vise andre…
2014 (engelsk)Konferansepaper, Oral presentation only (Fagfellevurdert)
Abstract [en]

Stable friction and positive slope of friction-speed is the typical criterion for a good clutch performance. Lubricated friction interfaces used for wet clutches produces different friction behavior depending on the lubricant conditions. Usually the lubricant conditions vary for different automatic transmission fluid (ATF) formulations implying e.g. water contamination and these conditions might influence the deterioration of the clutch plates. The aim of this paper is to verify additive adsorption on friction interfaces and ageing of the friction material in wet clutch system for a water contaminated commercial ATF (DEXRON® VI). Standard clutch plates are employed in an automated wet clutch test rig to evaluate the friction characteristics of the tested lubricant. For controlled test conditions (speed, contact pressure, oil temperature) and specific number of test cycles, the mean friction coefficient and the friction vs. speed relations are monitored during sliding test. The resultant tribofilms on the tested friction interface surfaces are characterized by means of Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM- EDS), Attenuated Total Reflectance -Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS analysis). The spectroscopic techniques were used to analyse adsorbed additives on friction interfaces and made it possible to correlate measured data to the specific friction behavior obtained after water contamination of the ATF.

HSV kategori
Forskningsprogram
Maskinelement; Kemisk teknologi
Identifikatorer
urn:nbn:se:ltu:diva-34688 (URN)8f48826e-0d1e-41e7-ace4-2404bb506b13 (Lokal ID)8f48826e-0d1e-41e7-ace4-2404bb506b13 (Arkivnummer)8f48826e-0d1e-41e7-ace4-2404bb506b13 (OAI)
Konferanse
Nordic Symposium on Tribology : 10/06/2014 - 13/06/2014
Merknad
Godkänd; 2014; 20140618 (andbra)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2018-04-05bibliografisk kontrollert
Fatima, N., Minami, I., Holmgren, A., Marklund, P. & Larsson, R. (2014). Adsorption of ATF additives on wet clutch friction interfaces under water contaminated lubricant conditions (ed.). Paper presented at Nordic Symposium on Tribology : 10/06/2014 - 13/06/2014. Paper presented at Nordic Symposium on Tribology : 10/06/2014 - 13/06/2014.
Åpne denne publikasjonen i ny fane eller vindu >>Adsorption of ATF additives on wet clutch friction interfaces under water contaminated lubricant conditions
Vise andre…
2014 (engelsk)Konferansepaper, Oral presentation only (Fagfellevurdert)
Abstract [en]

Stable friction and positive slope of friction-speed is the typical criterion for a good clutch performance. Lubricated friction interfaces used for wet clutches produces different friction behavior depending on the lubricant conditions. Usually the lubricant conditions vary for different automatic transmission fluid (ATF) formulations implying e.g. water contamination and these conditions might influence the deterioration of the clutch plates. The aim of this paper is to verify additive adsorption on friction interfaces and ageing of the friction material in wet clutch system for a water contaminated commercial ATF (DEXRON® VI). Standard clutch plates are employed in an automated wet clutch test rig to evaluate the friction characteristics of the tested lubricant. For controlled test conditions (speed, contact pressure, oil temperature) and specific number of test cycles, the mean friction coefficient and the friction vs. speed relations are monitored during sliding test. The resultant tribofilms on the tested friction interface surfaces are characterized by means of Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM- EDS), Attenuated Total Reflectance -Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS analysis). The spectroscopic techniques were used to analyse adsorbed additives on friction interfaces and made it possible to correlate measured data to the specific friction behavior obtained after water contamination of the ATF.

HSV kategori
Forskningsprogram
Maskinelement; Kemisk teknologi
Identifikatorer
urn:nbn:se:ltu:diva-37182 (URN)b1e7f3db-edc4-4dc7-bd7c-65a5869a3044 (Lokal ID)b1e7f3db-edc4-4dc7-bd7c-65a5869a3044 (Arkivnummer)b1e7f3db-edc4-4dc7-bd7c-65a5869a3044 (OAI)
Konferanse
Nordic Symposium on Tribology : 10/06/2014 - 13/06/2014
Merknad
Godkänd; 2014; 20140616 (nowfat)Tilgjengelig fra: 2016-10-03 Laget: 2016-10-03 Sist oppdatert: 2018-04-05bibliografisk kontrollert
Fatima, N. (2014). Impact of water contamination and system design on wet clutch tribological performance (ed.). (Doctoral dissertation). Paper presented at . : Luleå tekniska universitet
Åpne denne publikasjonen i ny fane eller vindu >>Impact of water contamination and system design on wet clutch tribological performance
2014 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Wet clutches are lubricated machine components which utilize friction to transfer torque and thus establish connection between shafts rotating at different speeds. They are used in automatic transmission as shifting device or lockup clutch. As well as cooling the contacting surfaces, the lubrication provides controlled friction, smooth performance and long life. Because of this advantage, wet clutches are applicable for heavy duty vehicles (e.g. construction equipment, tractors) to handle high power. However, like any other tribological system, wet clutch performance is dependent on several factors concerning operating conditions, system design etc. As a friction generating machine component, the degradation of the lubricant and the contacting clutch surfaces are continuous process and the friction behavior also changes consequently with the progression of the system deterioration and that directly influences the clutch performance. So, to investigate the clutch influencing factors and fundamental understanding of the interaction mechanism is of great interest. Though wet clutches were immensely studied earlier to investigate different issues, there was lack of clear understanding and knowledge concerning water contamination problem and the system design parameters. The main aim of this thesis is to experimentally evaluate and explain the impact of water contamination and to verify different system design parameters’ influence on wet clutch tribological performance. The study focused on the wet clutches in automatic transmissions. Initially the thesis reviews the state of the art in wet clutch research, discusses the motivation for the current research aim and clarifies the goals of the investigation. Later the details of the experimental method and findings are discussed in this thesis. Since evaluating the friction behaviour in desired environment is the key requirement, an automated wet clutch test rig was utilized to carry out the friction test where operating conditions (slip time, oil temperature, contact pressure/load, sliding speed) can be controlled and the output torque, contact temperature etc. can monitored. This suitable test equipment was designed for standard paper based friction plate and steel separator plate lubricated with automatic transmission fluid. Instead of using a multiple clutch plate configuration, as in real applications, a single friction and reaction plate arrangement is considered to simplify the analyses.In the first part of the thesis the effect of water contamination on wet clutch tribological performances is experimentally investigated. The study reveals that both the friction reliability and the friction-velocity relation are influenced by the change in the friction behaviour for a water contaminated lubricant. It is shown that the friction level increased for the addition of water in the system. This is not a desirable clutch frictional behaviour for maintaining frictional stability. The increase of friction for added water is influenced by the water amount but not by the water exposure time. Then the study is continued for longer test to evaluate the ageing of the friction interfaces and the lubricant. Though water does not show any long term effect on water contaminated ATF as it is seen in case of friction interfaces, the short term effect in the surface active additives is observed in the current research. This finding also supported the investigation on the water contaminated friction interface degradation and the effect of water on additive adsorption of the contacting surfaces. It was found that the addition of water in ATF intensifies the mean friction coefficient, but in the long run the loss of friction much faster and high, which can in fact degrade the clutch life faster as well. Two simplified ATF was also analysed along with the commercial fully formulated ATF for investigating the water impact to get a simple and comprehensive overview of the consequence. In the second part of this thesis, the influence of the clutch’s output shaft’s stiffness and inertia on the clutch system‘s friction reliability is experimentally evaluated. Test results show that the change in the clutch frictional behaviour with time and degradation can largely influence by the choice of these design factors. This can provide different outcome concerning clutch frictional performance and shudder sensitivity. Shudder tendency is seen to be increased for decreased torsion shaft stiffness. High frictional losses and clutch degradation are observed for systems with less inertia.

sted, utgiver, år, opplag, sider
Luleå tekniska universitet, 2014
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
HSV kategori
Forskningsprogram
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-26262 (URN)d6394d62-2f58-4ca9-8515-3a027f6659b3 (Lokal ID)978-91-7583-011-7 (ISBN)978-91-7583-012-4 (ISBN)d6394d62-2f58-4ca9-8515-3a027f6659b3 (Arkivnummer)d6394d62-2f58-4ca9-8515-3a027f6659b3 (OAI)
Merknad
Godkänd; 2014; 20140811 (nowfat); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Nowshir Fatima Ämne: Maskinelement/Machine Elements Avhandling: Impact of Water Contamination and System Design on Wet Clutch Tribological Performance Opponent: Dr Amaya Igartua, Fundacion Tekniker, Procesos de Fabricacion, Eibar, Spanien Ordförande: Professor Pär Marklund, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Fredag den 24 oktober 2014, kl. 10.00 Plats: E231, Luleå tekniska universitetTilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2018-01-10bibliografisk kontrollert
Fatima, N., Holmgren, A., Marklund, P., Mathew, A. P. & Larsson, R. (2013). Degradation mechanism of water contaminated automatic transmission fluid (ATF) in wet clutch system (ed.). Paper presented at World Tribology Congress : 08/09/2013 - 13/09/2013. Paper presented at World Tribology Congress : 08/09/2013 - 13/09/2013.
Åpne denne publikasjonen i ny fane eller vindu >>Degradation mechanism of water contaminated automatic transmission fluid (ATF) in wet clutch system
Vise andre…
2013 (engelsk)Konferansepaper, Oral presentation only (Fagfellevurdert)
HSV kategori
Forskningsprogram
Maskinelement; Kemisk teknologi; Trä och bionanokompositer
Identifikatorer
urn:nbn:se:ltu:diva-31871 (URN)84919457798 (Scopus ID)62ed687e-988f-48eb-b79d-efcc26b17f6e (Lokal ID)62ed687e-988f-48eb-b79d-efcc26b17f6e (Arkivnummer)62ed687e-988f-48eb-b79d-efcc26b17f6e (OAI)
Konferanse
World Tribology Congress : 08/09/2013 - 13/09/2013
Merknad
Godkänd; 2013; 20140214 (andbra)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2018-04-05bibliografisk kontrollert
Fatima, N., Marklund, P. & Larsson, R. (2013). Influence of clutch output shaft inertia and stiffness on the performance of the wet clutch (ed.). Paper presented at . Tribology Transactions, 56(2), 310-319
Åpne denne publikasjonen i ny fane eller vindu >>Influence of clutch output shaft inertia and stiffness on the performance of the wet clutch
2013 (engelsk)Inngår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 56, nr 2, s. 310-319Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Being a part of the complex mass, spring and damper system in a driveline, the choice of design factors like, output shaft stiffness and inertia of a wet clutch system can influence its performance. The effects of these parameters are experimentally evaluated in this paper. Widely used commercial paper based friction plates with standard steel reaction plates are tested with four different stiffness and inertia combinations in a recently developed wet clutch test rig. A low inertia system in general showed a faster degradation and shorter clutch life for high torsional oscillation. Besides the system becomes more shudder sensitive for lower natural frequency in case of less stiff system. The less stiff output shaft with low inertia showed the highest shudder tendency among the four conditions. The differences in performance for different output shaft conditions become noticeable for numerous clutch engagements or a degraded system. The effect of different shaft design conditions is also illuminated in the topographical analysis of the separators’ surfaces and morphological study of frictional surfaces. This study reveals the influence of both inertia and stiffness not only on shudder sensitivity of the system but also on the clutch frictional performance as well as the overall clutch life.

HSV kategori
Forskningsprogram
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-5135 (URN)10.1080/10402004.2012.748236 (DOI)000315686900018 ()2-s2.0-84878827731 (Scopus ID)327c4fbb-a48c-42ed-ba37-238b093820c4 (Lokal ID)327c4fbb-a48c-42ed-ba37-238b093820c4 (Arkivnummer)327c4fbb-a48c-42ed-ba37-238b093820c4 (OAI)
Merknad
Validerad; 2013; 20130201 (andbra)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Fatima, N., Marklund, P. & Larsson, R. (2013). Study on the wet clutch friction interfaces for humid lubrication condition (ed.). Paper presented at International Tribology Symposium of IFToMM : 19/03/2013 - 21/03/2013. Paper presented at International Tribology Symposium of IFToMM : 19/03/2013 - 21/03/2013.
Åpne denne publikasjonen i ny fane eller vindu >>Study on the wet clutch friction interfaces for humid lubrication condition
2013 (engelsk)Konferansepaper, Oral presentation only (Fagfellevurdert)
Abstract [en]

The friction influencing parameters also influence the wet clutch sliding surface conditions. The tribofilm formations as well as the chemical and mechanical degradation for frictional interfaces can be different for the choice of the lubricant conditions. The present investigations revealed the effects of water contamination in automatic transmission fluid (ATF) not only on the frictional performance, but also on the friction interfaces. The surface profiles of the tested separator plates, the EDS-SEM (Scanning Electron Microscopy-Energy-dispersive X-ray spectroscopy) analysis of the friction interfaces and optical microscopy for the used friction liners showed the difference in surface morphology, adsorption of additive elements, permeability and porosity for a humid clutch environment.

HSV kategori
Forskningsprogram
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-39320 (URN)e026a65f-dbd6-4539-aa7f-daaa57e676e3 (Lokal ID)e026a65f-dbd6-4539-aa7f-daaa57e676e3 (Arkivnummer)e026a65f-dbd6-4539-aa7f-daaa57e676e3 (OAI)
Konferanse
International Tribology Symposium of IFToMM : 19/03/2013 - 21/03/2013
Merknad
Godkänd; 2013; 20130415 (nowfat)Tilgjengelig fra: 2016-10-03 Laget: 2016-10-03 Sist oppdatert: 2018-03-09bibliografisk kontrollert
Organisasjoner