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Application of elastic-plastic static friction models to rough surfaces with asymmetric asperity distribution / Chul Hee Lee in Transactions of the ASME . Journal of tribology, Vol. 132 N° 3 (Juillet 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 3 (Juillet 2010) . - 11 p. Titre : Application of elastic-plastic static friction models to rough surfaces with asymmetric asperity distribution Type de document : texte imprimé Auteurs : Chul Hee Lee, Auteur ; Melih Eriten, Auteur ; Andreas A. Polycarpou, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Rough  surfaces  Sliding  friction  Stiction  Surface  roughness Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Asymmetric height distribution in surface roughness is important in many engineering surfaces, such as in constant velocity (CV) joints, where specific manufacturing processes could result in such surfaces. Even if the initial surfaces exhibit symmetric roughness, the running-in and sliding processes could result in asymmetric roughness distributions. In this paper, the effect of asymmetric asperity height distribution on the static friction coefficient is investigated theoretically and experimentally. The asymmetry of the surface roughness is modeled using the Pearson system of frequency curves. Two elastic-plastic static friction models, the Kogut–Etsion (KE) and Cohen–Kligerman–Etsion (CKE) models are adapted to account for asymmetric roughness and employed to obtain the tangential and normal contact forces. Static friction experiments using CV joint roller and housing surfaces, which exhibit different levels of surface roughness, were performed and directly compared with the KE and CKE static friction models using both a symmetric Gaussian as well as Pearson distributions of asperity heights. It is found that the KE model with the Pearson distribution compares favorably with the experimental measurements. Note de contenu : Erratum: “Application of Elastic-Plastic Static Friction Models to Rough Surfaces With Asymmetric Asperity Distribution” [Journal of Tribology, 2010, 132(3), p. 031602] Chul-Hee Lee et al. J. Tribol. 132, 047001 (2010) DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Application of elastic-plastic static friction models to rough surfaces with asymmetric asperity distribution [texte imprimé] / Chul Hee Lee, Auteur ; Melih Eriten, Auteur ; Andreas A. Polycarpou, Auteur . - 2011 . - 11 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 3 (Juillet 2010) . - 11 p. Mots-clés : Rough  surfaces  Sliding  friction  Stiction  Surface  roughness Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Asymmetric height distribution in surface roughness is important in many engineering surfaces, such as in constant velocity (CV) joints, where specific manufacturing processes could result in such surfaces. Even if the initial surfaces exhibit symmetric roughness, the running-in and sliding processes could result in asymmetric roughness distributions. In this paper, the effect of asymmetric asperity height distribution on the static friction coefficient is investigated theoretically and experimentally. The asymmetry of the surface roughness is modeled using the Pearson system of frequency curves. Two elastic-plastic static friction models, the Kogut–Etsion (KE) and Cohen–Kligerman–Etsion (CKE) models are adapted to account for asymmetric roughness and employed to obtain the tangential and normal contact forces. Static friction experiments using CV joint roller and housing surfaces, which exhibit different levels of surface roughness, were performed and directly compared with the KE and CKE static friction models using both a symmetric Gaussian as well as Pearson distributions of asperity heights. It is found that the KE model with the Pearson distribution compares favorably with the experimental measurements. Note de contenu : Erratum: “Application of Elastic-Plastic Static Friction Models to Rough Surfaces With Asymmetric Asperity Distribution” [Journal of Tribology, 2010, 132(3), p. 031602] Chul-Hee Lee et al. J. Tribol. 132, 047001 (2010) DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Assessment of elliptical conformal hertz analysis applied to constant velocity joints / Chul Hee Lee in Transactions of the ASME . Journal of tribology, Vol. 132 N° 2 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 03 p. Titre : Assessment of elliptical conformal hertz analysis applied to constant velocity joints Type de document : texte imprimé Auteurs : Chul Hee Lee, Auteur ; Andreas A. Polycarpou, Auteur Année de publication : 2011 Article en page(s) : 03 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Ball  bearings  Finite  element  analysis  Mechanical  contact  Rolling  bearings Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : To analyze the contact between two spherical bodies with different radii of curvature, the three-dimensional (3D) Hertz theory for elliptical contact is typically used. When the two contacting bodies have high conformity, such as the case for ball-in-groove, the Hertz theory may break down. In this research, finite element analysis (FEA) was used to assess the validity of 3D Hertz theory as found in the roller-housing contact of constant velocity joints. The contact area, normal approach, and contact pressure results show that Hertz agrees with FEA predictions for low compressive loads, where the contact ellipse is within the geometrical contact dimensions. At higher loads the contact ellipse extends beyond the contacting geometrical dimensions and the simplified analytical Hertz results diverge from the FEA results. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Assessment of elliptical conformal hertz analysis applied to constant velocity joints [texte imprimé] / Chul Hee Lee, Auteur ; Andreas A. Polycarpou, Auteur . - 2011 . - 03 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 03 p. Mots-clés : Ball  bearings  Finite  element  analysis  Mechanical  contact  Rolling  bearings Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : To analyze the contact between two spherical bodies with different radii of curvature, the three-dimensional (3D) Hertz theory for elliptical contact is typically used. When the two contacting bodies have high conformity, such as the case for ball-in-groove, the Hertz theory may break down. In this research, finite element analysis (FEA) was used to assess the validity of 3D Hertz theory as found in the roller-housing contact of constant velocity joints. The contact area, normal approach, and contact pressure results show that Hertz agrees with FEA predictions for low compressive loads, where the contact ellipse is within the geometrical contact dimensions. At higher loads the contact ellipse extends beyond the contacting geometrical dimensions and the simplified analytical Hertz results diverge from the FEA results. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Experimental and FEA scratch of magnetic storage thin-film disks to correlate magnetic signal degradation with permanent deformation / Raja R. Katta in Transactions of the ASME . Journal of tribology, Vol. 132 N° 2 (Avril 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 11 p. Titre : Experimental and FEA scratch of magnetic storage thin-film disks to correlate magnetic signal degradation with permanent deformation Type de document : texte imprimé Auteurs : Raja R. Katta, Auteur ; Andreas A. Polycarpou, Auteur ; Sung-Chang Lee, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Atomic  force  microscopy  Deformation  Demagnetisation  Finite  element  analysis  Friction  Hard  discs  Magnetic  multilayers  Magnetic  storage  Magnetic  thin  film  devices  Nanoindentation  Perpendicular  magnetic  recording Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Scratch-related magnetic signal degradation can occur during magnetic storage hard disk drive operations when the read-write heads contact the spinning multilayer disks. To investigate this phenomenon, controlled nanoscratch experiments were performed on perpendicular magnetic recording media using various indenters of different radii of curvature. Various loading conditions were used to cause permanent scratches that were measured using atomic force microscopy. The nanoscratch experiments were simulated using finite element analysis (FEA) that included the detailed nanometer scale thin-film multilayer mechanical properties. The permanently deformed field in the subsurface magnetic recording layer was extracted from the FEA results. The residual scratch widths measured on the surface of the magnetic storage disk were directly compared with the residual subsurface widths of the region on the magnetic recording layer, where extensive permanent lateral deformation was present. It was found that the subsurface widths of the deformed regions were significantly larger than the surface scratch widths. Thus, subsurface thin-film layers, such as the magnetic recording layer, could be damaged without observable damage to the protective top surface carbon overcoat. The exact location and extent of damage to the magnetic recording layer depends on the scratch load, size of scratch tip, and the friction at the interface. Such permanent deformation in magnetic recording layer could lead to demagnetization, which has been reported in the literature. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Experimental and FEA scratch of magnetic storage thin-film disks to correlate magnetic signal degradation with permanent deformation [texte imprimé] / Raja R. Katta, Auteur ; Andreas A. Polycarpou, Auteur ; Sung-Chang Lee, Auteur . - 2011 . - 11 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 2 (Avril 2010) . - 11 p. Mots-clés : Atomic  force  microscopy  Deformation  Demagnetisation  Finite  element  analysis  Friction  Hard  discs  Magnetic  multilayers  Magnetic  storage  Magnetic  thin  film  devices  Nanoindentation  Perpendicular  magnetic  recording Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Scratch-related magnetic signal degradation can occur during magnetic storage hard disk drive operations when the read-write heads contact the spinning multilayer disks. To investigate this phenomenon, controlled nanoscratch experiments were performed on perpendicular magnetic recording media using various indenters of different radii of curvature. Various loading conditions were used to cause permanent scratches that were measured using atomic force microscopy. The nanoscratch experiments were simulated using finite element analysis (FEA) that included the detailed nanometer scale thin-film multilayer mechanical properties. The permanently deformed field in the subsurface magnetic recording layer was extracted from the FEA results. The residual scratch widths measured on the surface of the magnetic storage disk were directly compared with the residual subsurface widths of the region on the magnetic recording layer, where extensive permanent lateral deformation was present. It was found that the subsurface widths of the deformed regions were significantly larger than the surface scratch widths. Thus, subsurface thin-film layers, such as the magnetic recording layer, could be damaged without observable damage to the protective top surface carbon overcoat. The exact location and extent of damage to the magnetic recording layer depends on the scratch load, size of scratch tip, and the friction at the interface. Such permanent deformation in magnetic recording layer could lead to demagnetization, which has been reported in the literature. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Impact of a fixed-length rigid cylinder on an elastic-plastic homogeneous body / Raja R. Katta in Transactions of the ASME . Journal of tribology, Vol. 132 N° 4 (Octobre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 132 N° 4 (Octobre 2010) . - 11 p. Titre : Impact of a fixed-length rigid cylinder on an elastic-plastic homogeneous body Type de document : texte imprimé Auteurs : Raja R. Katta, Auteur ; Andreas A. Polycarpou, Auteur Année de publication : 2011 Article en page(s) : 11 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Disc  drives  Elasticity  Finite  element  analysis  Hard  discs  Impact  testing  Magnetic  storage  Plasticity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A contact mechanics (CM) based model of a fixed-length rigid cylinder impacting a homogeneous elastic-plastic homogeneous body was developed and includes an improved method of estimating the residual depth after impact. The nonlinear elastic behavior during unloading was accounted for to develop an improved coefficient of restitution model. The impact model was applied to study a practical case of a cylindrical feature on the slider of a magnetic storage hard disk drive impacting the disk to predict various critical impact contact parameters. The CM model was validated using a plane strain finite element model and it was found that a cylindrical feature with a longer length results in a substantial alleviation of impact damage. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...] [article] Impact of a fixed-length rigid cylinder on an elastic-plastic homogeneous body [texte imprimé] / Raja R. Katta, Auteur ; Andreas A. Polycarpou, Auteur . - 2011 . - 11 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 132 N° 4 (Octobre 2010) . - 11 p. Mots-clés : Disc  drives  Elasticity  Finite  element  analysis  Hard  discs  Impact  testing  Magnetic  storage  Plasticity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A contact mechanics (CM) based model of a fixed-length rigid cylinder impacting a homogeneous elastic-plastic homogeneous body was developed and includes an improved method of estimating the residual depth after impact. The nonlinear elastic behavior during unloading was accounted for to develop an improved coefficient of restitution model. The impact model was applied to study a practical case of a cylindrical feature on the slider of a magnetic storage hard disk drive impacting the disk to predict various critical impact contact parameters. The CM model was validated using a plane strain finite element model and it was found that a cylindrical feature with a longer length results in a substantial alleviation of impact damage. DEWEY : 621.5 ISSN : 0742-4787 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JOTRE900013 [...]

Investigation of contact stiffness and contact damping for magnetic storage head-disk interfaces / Xi Shi in Transactions of the ASME . Journal of tribology, Vol. 130 n°2 (Mars/Avril 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of tribology > Vol. 130 n°2 (Mars/Avril 2008) . - 9 p. Titre : Investigation of contact stiffness and contact damping for magnetic storage head-disk interfaces Type de document : texte imprimé Auteurs : Xi Shi, Auteur ; Andreas A. Polycarpou, Auteur Année de publication : 2008 Article en page(s) : 9 p. Note générale : Tribology Langues : Anglais (eng) Résumé : As the areal density of magnetic disk storage continues to increase and head-disk spacing decreases, contact between the recording slider and the rotating media becomes imminent. In order to predict contact forces, fly-height modulations, and off-track motions, dynamic models are typically used. A critical element of these models is the contact stiffness and damping arising from the interfacial interaction between the slider and the disk. In this paper, we review different models for predicting contact stiffness based on roughness and layered media and then we report experimental data of both contact stiffness and contact damping of typical head-disk interfaces. It is found that the contact stiffness models (based on roughness alone) overpredict the contact stiffness of actual head-disk interfaces by as much as an order of magnitude. Also, it is found that the contact damping ratio is typically few percent and its behavior is substrate dependent. In addition, the effects of a molecularly thin lubricant and humidity on contact stiffness and damping were experimentally investigated and no significant effects were found. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468038 [article] Investigation of contact stiffness and contact damping for magnetic storage head-disk interfaces [texte imprimé] / Xi Shi, Auteur ; Andreas A. Polycarpou, Auteur . - 2008 . - 9 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 n°2 (Mars/Avril 2008) . - 9 p. Résumé : As the areal density of magnetic disk storage continues to increase and head-disk spacing decreases, contact between the recording slider and the rotating media becomes imminent. In order to predict contact forces, fly-height modulations, and off-track motions, dynamic models are typically used. A critical element of these models is the contact stiffness and damping arising from the interfacial interaction between the slider and the disk. In this paper, we review different models for predicting contact stiffness based on roughness and layered media and then we report experimental data of both contact stiffness and contact damping of typical head-disk interfaces. It is found that the contact stiffness models (based on roughness alone) overpredict the contact stiffness of actual head-disk interfaces by as much as an order of magnitude. Also, it is found that the contact damping ratio is typically few percent and its behavior is substrate dependent. In addition, the effects of a molecularly thin lubricant and humidity on contact stiffness and damping were experimentally investigated and no significant effects were found. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleid=1468038