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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 [...]