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Model describing material-dependent deformation behavior in high-velocity metal forming processes / Håkan Hallberg in Journal of engineering mechanics, Vol. 135 N° 4 (Avril 2009) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 135 N° 4 (Avril 2009) . - pp. 345-357 Titre : Model describing material-dependent deformation behavior in high-velocity metal forming processes Type de document : texte imprimé Auteurs : Håkan Hallberg, Auteur ; Kristina Ryttberg, Auteur ; Matti Ristinmaa, Auteur Article en page(s) : pp. 345-357 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Constitutive  models  Viscoelasticity  Continuum  mechanics  Experimentation  Deformation  Velocity. Résumé : A constitutive model for rate-dependent and thermomechanically coupled plasticity at finite strains is presented. The plasticity model is based on a J2 model and rate-dependent behavior is included by use of a Perzyna-type formulation. Adiabatic heating effects are handled in a consistent way and not, as is a common assumption, through a constant conversion of the internal work rate into rate of heating. The conversion factor is instead derived from thermodynamic considerations. The stored energy is assumed to be a function of a single internal variable which differs from the effective plastic strain. This allows a thermodynamically consistent formulation to be obtained which, as shown, can be calibrated by use of simple procedures. Choosing 100Cr6 steel in two differently heat treated conditions as prototype material, experimental tests are performed, enabling the model to be calibrated. Significant differences in deformation behavior are noted as the differently heat treated specimens are compared. In addition, the local stress-updating procedure is reduced to a single scalar equation, permitting a very efficient numerical implementation of the model. The constitutive formulation proposed was employed in an explicit finite element solver, illustrative simulations of a high-velocity metal forming process being performed to demonstrate the capabilities of the model and certain characteristic traits of the materials that were studied. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...] [article] Model describing material-dependent deformation behavior in high-velocity metal forming processes [texte imprimé] / Håkan Hallberg, Auteur ; Kristina Ryttberg, Auteur ; Matti Ristinmaa, Auteur . - pp. 345-357. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 4 (Avril 2009) . - pp. 345-357 Mots-clés : Constitutive  models  Viscoelasticity  Continuum  mechanics  Experimentation  Deformation  Velocity. Résumé : A constitutive model for rate-dependent and thermomechanically coupled plasticity at finite strains is presented. The plasticity model is based on a J2 model and rate-dependent behavior is included by use of a Perzyna-type formulation. Adiabatic heating effects are handled in a consistent way and not, as is a common assumption, through a constant conversion of the internal work rate into rate of heating. The conversion factor is instead derived from thermodynamic considerations. The stored energy is assumed to be a function of a single internal variable which differs from the effective plastic strain. This allows a thermodynamically consistent formulation to be obtained which, as shown, can be calibrated by use of simple procedures. Choosing 100Cr6 steel in two differently heat treated conditions as prototype material, experimental tests are performed, enabling the model to be calibrated. Significant differences in deformation behavior are noted as the differently heat treated specimens are compared. In addition, the local stress-updating procedure is reduced to a single scalar equation, permitting a very efficient numerical implementation of the model. The constitutive formulation proposed was employed in an explicit finite element solver, illustrative simulations of a high-velocity metal forming process being performed to demonstrate the capabilities of the model and certain characteristic traits of the materials that were studied. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JENMDT000 [...]