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A new approach for including cage flexibility in dynamic bearing models by using combined explicit finite and discrete element methods / Ankur Ashtekar in Transactions of the ASME . Journal of tribology, Vol. 134 N° 04 (Octobre 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 134 N° 04 (Octobre 2012) . - 12 p. Titre : A new approach for including cage flexibility in dynamic bearing models by using combined explicit finite and discrete element methods Type de document : texte imprimé Auteurs : Ankur Ashtekar, Auteur ; Farshid Sadeghi, Auteur Année de publication : 2012 Article en page(s) : 12 p. Note générale : tribology Langues : Anglais (eng) Mots-clés : bearing  dynamics;  cage  flexibility;  finite  elements;  disrcere  elements Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this investigation, a new approach was developed to study the influence of cage flexibility on the dynamics of inner and outer races and balls in a bearing. A 3D explicit finite element model (EFEM) of the cage was developed and combined with an existing discrete element dynamic bearing model (DBM) with six degrees of freedom. The EFEM was used to determine the cage dynamics, deformation, and resulting stresses in a ball bearing under various operating conditions. A novel algorithm was developed to determine the contact forces between the rigid balls and the flexible (deformable) cage. In this new flexible cage dynamic bearing model, the discrete and finite element models interact at each time step to determine the position, velocity, acceleration, and forces of all bearing components. The combined model was applied to investigate the influence of cage flexibility on ball-cage interactions and the resulting ball motion, cage whirl, and the effects of shaft misalignment. The model demonstrates that cage flexibility (deflection) has a significant influence on the ball-cage interaction. The results from this investigation demonstrate that the magnitude of ball-cage impacts and the ball sliding reduced in the presence of a flexible cage; however, as expected, the cage overall motion and angular velocity were largely unaffected by the cage flexibility. During high-speed operation, centrifugal forces contribute substantially to the total cage deformation and resulting stresses. When shaft misalignment is considered, stress cycles are experienced in the bridge and rail sections of the cage where fatigue failures have been observed in practice and in experimental studies. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE9000134000004 [...] [article] A new approach for including cage flexibility in dynamic bearing models by using combined explicit finite and discrete element methods [texte imprimé] / Ankur Ashtekar, Auteur ; Farshid Sadeghi, Auteur . - 2012 . - 12 p. tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 134 N° 04 (Octobre 2012) . - 12 p. Mots-clés : bearing  dynamics;  cage  flexibility;  finite  elements;  disrcere  elements Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this investigation, a new approach was developed to study the influence of cage flexibility on the dynamics of inner and outer races and balls in a bearing. A 3D explicit finite element model (EFEM) of the cage was developed and combined with an existing discrete element dynamic bearing model (DBM) with six degrees of freedom. The EFEM was used to determine the cage dynamics, deformation, and resulting stresses in a ball bearing under various operating conditions. A novel algorithm was developed to determine the contact forces between the rigid balls and the flexible (deformable) cage. In this new flexible cage dynamic bearing model, the discrete and finite element models interact at each time step to determine the position, velocity, acceleration, and forces of all bearing components. The combined model was applied to investigate the influence of cage flexibility on ball-cage interactions and the resulting ball motion, cage whirl, and the effects of shaft misalignment. The model demonstrates that cage flexibility (deflection) has a significant influence on the ball-cage interaction. The results from this investigation demonstrate that the magnitude of ball-cage impacts and the ball sliding reduced in the presence of a flexible cage; however, as expected, the cage overall motion and angular velocity were largely unaffected by the cage flexibility. During high-speed operation, centrifugal forces contribute substantially to the total cage deformation and resulting stresses. When shaft misalignment is considered, stress cycles are experienced in the bridge and rail sections of the cage where fatigue failures have been observed in practice and in experimental studies. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE9000134000004 [...]

A new approach to modeling surface defects in bearing dynamics simulations / Ankur Ashtekar 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) . - 8 p. Titre : A new approach to modeling surface defects in bearing dynamics simulations Type de document : texte imprimé Auteurs : Ankur Ashtekar, Auteur ; Farshid Sadeghi, Auteur ; Lars-Erik Stacke, Auteur Article en page(s) : 8 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Product  quality  Bearings  Dynamics  (Mechanics)  Force  Deflection  Engineering  simulation  Modeling  Motion Résumé : A dynamic model for deep groove and angular contact ball bearings was developed to investigate the influence of race defects on the motions of bearing components (i.e., inner and outer races, cage, and balls). In order to determine the effects of dents on the bearing dynamics, a model was developed to determine the force-deflection relationship between an ellipsoid and a dented semi-infinite domain. The force-deflection relationship for dented surfaces was then incorporated in the bearing dynamic model by replacing the well-known Hertzian force-deflection relationship whenever a ball/dent interaction occurs. In this investigation, all bearing components have six degrees-of-freedom. Newton’s laws are used to determine the motions of all bearing elements, and an explicit fourth-order Runge–Kutta algorithm with a variable or constant step size was used to integrate the equations of motion. A model was used to study the effect of dent size, dent location, and inner race speed on bearing components. The results indicate that surface defects and irregularities like dent have a severe effect on bearing motion and forces. Furthermore, these effects are even more severe for high-speed applications. The results also demonstrate that a single dent can affect the forces and motion throughout the entire bearing and on all bearing components. However, the location of the dent dictates the magnitude of its influence on each bearing component. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468093#D [...] [article] A new approach to modeling surface defects in bearing dynamics simulations [texte imprimé] / Ankur Ashtekar, Auteur ; Farshid Sadeghi, Auteur ; Lars-Erik Stacke, Auteur . - 8 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 8 p. Mots-clés : Product  quality  Bearings  Dynamics  (Mechanics)  Force  Deflection  Engineering  simulation  Modeling  Motion Résumé : A dynamic model for deep groove and angular contact ball bearings was developed to investigate the influence of race defects on the motions of bearing components (i.e., inner and outer races, cage, and balls). In order to determine the effects of dents on the bearing dynamics, a model was developed to determine the force-deflection relationship between an ellipsoid and a dented semi-infinite domain. The force-deflection relationship for dented surfaces was then incorporated in the bearing dynamic model by replacing the well-known Hertzian force-deflection relationship whenever a ball/dent interaction occurs. In this investigation, all bearing components have six degrees-of-freedom. Newton’s laws are used to determine the motions of all bearing elements, and an explicit fourth-order Runge–Kutta algorithm with a variable or constant step size was used to integrate the equations of motion. A model was used to study the effect of dent size, dent location, and inner race speed on bearing components. The results indicate that surface defects and irregularities like dent have a severe effect on bearing motion and forces. Furthermore, these effects are even more severe for high-speed applications. The results also demonstrate that a single dent can affect the forces and motion throughout the entire bearing and on all bearing components. However, the location of the dent dictates the magnitude of its influence on each bearing component. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468093#D [...]