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Computation of sliding friction and ratcheting strain of sintered and hardened steels under contact fatigue conditions / N. Govindarajan in Transactions of the ASME . Journal of tribology, Vol. 130 N° 4 (Octobre 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 10 p. Titre : Computation of sliding friction and ratcheting strain of sintered and hardened steels under contact fatigue conditions Type de document : texte imprimé Auteurs : N. Govindarajan, Auteur ; R. Gnanamoorthy, Auteur Année de publication : 2015 Article en page(s) : 10 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Fatigue  Friction  Stress  Failure  Martensitic  steel  Sliding  friction  Steel  Pressure  Wear  Particulate  matter Résumé : Fatigue properties of powder metallurgy parts are affected mainly by the porosity fraction. Even though it has inferior mechanical and physical properties over the conventional materials, the application of powder metallurgy products in automotive fields is seen in recent trends. The rolling-sliding contact fatigue behavior of sintered and hardened steels has been investigated by performing experiments that represent practical sliding friction coefficient component prevailing in the medium- and heavy-duty bearings and gears. Introduction of sliding friction coefficient changes the typical failure pattern and wear rate of sintered and hardened steels. The sliding friction has been computed from available models and compared with the experimental data. The ratcheting strain has also been predicted for sintered and hardened steels for various contact pressures and sliding friction coefficients. The maximum value of this strain is responsible for surface crack initiation. The wear particle analysis is carried out for the sintered and hardened steels under rolling-sliding contact fatigue conditions. The ferrogram slides for pore free steel under the rolling-sliding contact fatigue conditions are also prepared to study the effect of porosity in wear mechanism. The characteristics of wear morphology and the size, shape, and concentration of worn particles for sintered and hardened steels are also analyzed for various rolling-sliding contact fatigue conditions. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468118 [article] Computation of sliding friction and ratcheting strain of sintered and hardened steels under contact fatigue conditions [texte imprimé] / N. Govindarajan, Auteur ; R. Gnanamoorthy, Auteur . - 2015 . - 10 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 10 p. Mots-clés : Fatigue  Friction  Stress  Failure  Martensitic  steel  Sliding  friction  Steel  Pressure  Wear  Particulate  matter Résumé : Fatigue properties of powder metallurgy parts are affected mainly by the porosity fraction. Even though it has inferior mechanical and physical properties over the conventional materials, the application of powder metallurgy products in automotive fields is seen in recent trends. The rolling-sliding contact fatigue behavior of sintered and hardened steels has been investigated by performing experiments that represent practical sliding friction coefficient component prevailing in the medium- and heavy-duty bearings and gears. Introduction of sliding friction coefficient changes the typical failure pattern and wear rate of sintered and hardened steels. The sliding friction has been computed from available models and compared with the experimental data. The ratcheting strain has also been predicted for sintered and hardened steels for various contact pressures and sliding friction coefficients. The maximum value of this strain is responsible for surface crack initiation. The wear particle analysis is carried out for the sintered and hardened steels under rolling-sliding contact fatigue conditions. The ferrogram slides for pore free steel under the rolling-sliding contact fatigue conditions are also prepared to study the effect of porosity in wear mechanism. The characteristics of wear morphology and the size, shape, and concentration of worn particles for sintered and hardened steels are also analyzed for various rolling-sliding contact fatigue conditions. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468118

Development of a novel oil cavitation jet peening system and cavitation jet erosion in aluminum alloy, AA 6063-T6 / A. Sahaya Grinspan in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 6 (Juin 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 6 (Juin 2009) . - 08 p. Titre : Development of a novel oil cavitation jet peening system and cavitation jet erosion in aluminum alloy, AA 6063-T6 Type de document : texte imprimé Auteurs : A. Sahaya Grinspan, Auteur ; R. Gnanamoorthy, Auteur Année de publication : 2009 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : Oil  cavitation  jet  peening;  high-speed  oil  jet;  alluminium  alloy Résumé : Compressive residual stresses that improve fatigue strength of material are obtained by peening the surface. Unlike traditional processes, a novel process of oil cavitation jet peening was developed. The process is based on implosion generated by the oil cavitation jet that plastically deforms the surface, imparting compressive residual stresses. The process developed involves injection of a high-speed oil jet (∼230 m/s) through a suitably designed nozzle, into an oil-filled chamber containing the specimen to be peened. The region of cavitation generation, growth, and collapse, at the various cavitation numbers, was recorded using high-speed photography. To optimize the process parameters, a simple erosion test was performed in aluminum alloy, AA 6063-T6, specimens. The impact pressure generated during the implosion of cavitation bubbles causes plastic deformation and erosion of the surface. The surface deformation and cavitation jet erosion in the exposed specimens were characterized using optical and scanning electron microscopies. The standoff distance, which measures jet impact zone of the specimen from nozzle, was optimized at 15 mm in a cavitation number (which is a measure of pressure ratio across the nozzle) of 0.0017. The surface deformation produced by collapse of the oil bubble was similar to impact of oil droplet on the surface. The material removal mechanism during implosion of the bubble is predominately by ductile shear deformation. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Development of a novel oil cavitation jet peening system and cavitation jet erosion in aluminum alloy, AA 6063-T6 [texte imprimé] / A. Sahaya Grinspan, Auteur ; R. Gnanamoorthy, Auteur . - 2009 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 6 (Juin 2009) . - 08 p. Mots-clés : Oil  cavitation  jet  peening;  high-speed  oil  jet;  alluminium  alloy Résumé : Compressive residual stresses that improve fatigue strength of material are obtained by peening the surface. Unlike traditional processes, a novel process of oil cavitation jet peening was developed. The process is based on implosion generated by the oil cavitation jet that plastically deforms the surface, imparting compressive residual stresses. The process developed involves injection of a high-speed oil jet (∼230 m/s) through a suitably designed nozzle, into an oil-filled chamber containing the specimen to be peened. The region of cavitation generation, growth, and collapse, at the various cavitation numbers, was recorded using high-speed photography. To optimize the process parameters, a simple erosion test was performed in aluminum alloy, AA 6063-T6, specimens. The impact pressure generated during the implosion of cavitation bubbles causes plastic deformation and erosion of the surface. The surface deformation and cavitation jet erosion in the exposed specimens were characterized using optical and scanning electron microscopies. The standoff distance, which measures jet impact zone of the specimen from nozzle, was optimized at 15 mm in a cavitation number (which is a measure of pressure ratio across the nozzle) of 0.0017. The surface deformation produced by collapse of the oil bubble was similar to impact of oil droplet on the surface. The material removal mechanism during implosion of the bubble is predominately by ductile shear deformation. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]