Approximate analytical model for hertzian elliptical wheel/rail or wheel/crossing contact problems / F.D. Fischer in Transactions of the ASME . Journal of tribology, Vol. 130 N° 4 (Octobre 2008)  

Public ISBD [article]  inTransactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 3 p. Titre : Approximate analytical model for hertzian elliptical wheel/rail or wheel/crossing contact problems Type de document : texte imprimé Auteurs : F.D. Fischer, Auteur ; M. Wiest, Auteur Année de publication : 2015 Article en page(s) : 3 p. Note générale : Tribology Langues : Anglais (eng) Mots-clés : Pressure Approximation Elastic constants Rails Wheels Résumé : The Hertzian contact theory is approximated according to a concept by Tanaka (2001, “A New Calculation Method of Hertz Elliptical Contact Pressure ,” ASME J. Tribol., 123, pp. 887–889) yielding simple analytical expressions for the elliptical semi-axes, the maximum contact pressure, the mutual approach and the contact spring constant. Several configurations are compared using the exact Hertz theory and the current approximation. The results agree within technical accuracy. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleID=1468139 [article] Approximate analytical model for hertzian elliptical wheel/rail or wheel/crossing contact problems [texte imprimé] / F.D. Fischer, Auteur ; M. Wiest, Auteur . - 2015 . - 3 p. Tribology Langues : Anglais (eng) in Transactions of the ASME . Journal of tribology > Vol. 130 N° 4 (Octobre 2008) . - 3 p. Mots-clés : Pressure Approximation Elastic constants Rails Wheels Résumé : The Hertzian contact theory is approximated according to a concept by Tanaka (2001, “A New Calculation Method of Hertz Elliptical Contact Pressure ,” ASME J. Tribol., 123, pp. 887–889) yielding simple analytical expressions for the elliptical semi-axes, the maximum contact pressure, the mutual approach and the contact spring constant. Several configurations are compared using the exact Hertz theory and the current approximation. The results agree within technical accuracy. En ligne : http://tribology.asmedigitalcollection.asme.org/article.aspx?articleID=1468139

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Modeling of diffusional phase transformation in multi-component systems with stoichiometric phases / J. Svoboda in Acta materialia, Vol. 58 N° 8 (Mai 2010)  

Public ISBD [article]  inActa materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 2905–2911 Titre : Modeling of diffusional phase transformation in multi-component systems with stoichiometric phases Type de document : texte imprimé Auteurs : J. Svoboda, Auteur ; F.D. Fischer, Auteur ; R. Abart, Auteur Année de publication : 2011 Article en page(s) : pp. 2905–2911 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Interdiffusion Intermetallics Phase transformation kinetics Modeling Kirkendall effect Résumé : In many multi-component systems, phases can be considered stoichiometric. If two phases not stably coexisting are brought into contact, multiple new phases may nucleate at the interface and develop into a sequence of layers with different phase compositions, which grow between the original phases. Inert markers at the original contact may show “splitting” of the marker (Kirkendall) plane, called polyfurcation. Nearly exclusively binary systems have been studied theoretically or experimentally. A thermodynamic model for the kinetics of diffusional phase transformation in multi-component systems and motion of the polyfurcated Kirkendall plane is derived by the thermodynamic extremal principle. The degrees of freedom of the system are discussed rigorously. The model is demonstrated on simulations of kinetics in binary three-phase and ternary four-phase systems. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000339 [article] Modeling of diffusional phase transformation in multi-component systems with stoichiometric phases [texte imprimé] / J. Svoboda, Auteur ; F.D. Fischer, Auteur ; R. Abart, Auteur . - 2011 . - pp. 2905–2911. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 2905–2911 Mots-clés : Interdiffusion Intermetallics Phase transformation kinetics Modeling Kirkendall effect Résumé : In many multi-component systems, phases can be considered stoichiometric. If two phases not stably coexisting are brought into contact, multiple new phases may nucleate at the interface and develop into a sequence of layers with different phase compositions, which grow between the original phases. Inert markers at the original contact may show “splitting” of the marker (Kirkendall) plane, called polyfurcation. Nearly exclusively binary systems have been studied theoretically or experimentally. A thermodynamic model for the kinetics of diffusional phase transformation in multi-component systems and motion of the polyfurcated Kirkendall plane is derived by the thermodynamic extremal principle. The degrees of freedom of the system are discussed rigorously. The model is demonstrated on simulations of kinetics in binary three-phase and ternary four-phase systems. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000339

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Substitutional diffusion in multicomponent solids with non-ideal sources and sinks for vacancies / F.D. Fischer in Acta materialia, Vol. 58 N° 7 (Avril 2010)  

Public ISBD [article]  inActa materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2698–2707 Titre : Substitutional diffusion in multicomponent solids with non-ideal sources and sinks for vacancies Type de document : texte imprimé Auteurs : F.D. Fischer, Auteur ; J. Svoboda, Auteur Année de publication : 2011 Article en page(s) : pp. 2698–2707 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Substitutional diffusion Vacancies Annihilation Residual stresses Non-equilibrium process Résumé : Based on previous work by the authors the diffusion equations for a multicomponent solid are derived. Generation and annihilation of vacancies are described by an evolution law which is directly coupled with an eigenstrain rate. Manning’s correlation factor f is used in the kinetic factor for diffusion of vacancies. In addition to presentation of the diffusion equations, a rigorous treatment of the boundary conditions, assuming no or an ideal source and sink for vacancies at the surface, is presented. As an instructive example development of the site fractions of the components and the eigenstress state are demonstrated for a multicomponent chemically inhomogeneous layer on a substrate. Both the role of nonlinear terms and the correlation factor f in the diffusion equations are studied. Computational procedures to calculate to the proper boundary conditions are also outlined. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000066 [article] Substitutional diffusion in multicomponent solids with non-ideal sources and sinks for vacancies [texte imprimé] / F.D. Fischer, Auteur ; J. Svoboda, Auteur . - 2011 . - pp. 2698–2707. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 7 (Avril 2010) . - pp. 2698–2707 Mots-clés : Substitutional diffusion Vacancies Annihilation Residual stresses Non-equilibrium process Résumé : Based on previous work by the authors the diffusion equations for a multicomponent solid are derived. Generation and annihilation of vacancies are described by an evolution law which is directly coupled with an eigenstrain rate. Manning’s correlation factor f is used in the kinetic factor for diffusion of vacancies. In addition to presentation of the diffusion equations, a rigorous treatment of the boundary conditions, assuming no or an ideal source and sink for vacancies at the surface, is presented. As an instructive example development of the site fractions of the components and the eigenstress state are demonstrated for a multicomponent chemically inhomogeneous layer on a substrate. Both the role of nonlinear terms and the correlation factor f in the diffusion equations are studied. Computational procedures to calculate to the proper boundary conditions are also outlined. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000066

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