Documents disponibles écrits par cet auteur

Extension of fracture mechanics principles to viscoelastic continuum media / Jaeseung Kim in Journal of engineering mechanics, Vol. 138 N° 4 (Avril 2012) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 138 N° 4 (Avril 2012) . - pp.317-326 Titre : Extension of fracture mechanics principles to viscoelastic continuum media Type de document : texte imprimé Auteurs : Jaeseung Kim, Auteur ; Sungho Kim, Auteur Année de publication : 2012 Article en page(s) : pp.317-326 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Asphalts  Mixtures  Viscoelasticity  Cracking  Damage  Biaxial  tests Résumé : The fracturing of materials is well known on the basis of the theory of fracture mechanics. An important concept in fracture mechanics theory is that crack propagation is governed by the fundamental material properties of energy dissipation and energy threshold. However, to apply the fracture mechanics approach and measure these properties, a notch needs to be introduced into a continuum body. This requires additional effort to make the notch, which is often sensitive to the formation of materials surrounding the area near the crack tip. These effects become more complex for a material that exhibits time, rate, and temperature dependency. To overcome these complexities and problems regarding fracture testing, this study used the analogy between the material’s behaviors with and without a notch. A transfer of the fracture mechanics principle to continuum viscoelastic media was the key to the model developed in this study. For this purpose, the energy release rate (G) which is theoretically derived from a viscoelastic cracked body, was transferred to a continuum body by employing the same energy principles but used in continuum damage mechanics. From the evaluation of the model for various mixtures at multiple temperatures, predictions made were in agreement with the expected results from the well-known fatigue model. Consequently, it is expected that the developed model will bridge the gap between viscoelastic fracture and continuum damage mechanics, and provide better cracking performance predictions of asphalt mixtures. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000335 [article] Extension of fracture mechanics principles to viscoelastic continuum media [texte imprimé] / Jaeseung Kim, Auteur ; Sungho Kim, Auteur . - 2012 . - pp.317-326. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 4 (Avril 2012) . - pp.317-326 Mots-clés : Asphalts  Mixtures  Viscoelasticity  Cracking  Damage  Biaxial  tests Résumé : The fracturing of materials is well known on the basis of the theory of fracture mechanics. An important concept in fracture mechanics theory is that crack propagation is governed by the fundamental material properties of energy dissipation and energy threshold. However, to apply the fracture mechanics approach and measure these properties, a notch needs to be introduced into a continuum body. This requires additional effort to make the notch, which is often sensitive to the formation of materials surrounding the area near the crack tip. These effects become more complex for a material that exhibits time, rate, and temperature dependency. To overcome these complexities and problems regarding fracture testing, this study used the analogy between the material’s behaviors with and without a notch. A transfer of the fracture mechanics principle to continuum viscoelastic media was the key to the model developed in this study. For this purpose, the energy release rate (G) which is theoretically derived from a viscoelastic cracked body, was transferred to a continuum body by employing the same energy principles but used in continuum damage mechanics. From the evaluation of the model for various mixtures at multiple temperatures, predictions made were in agreement with the expected results from the well-known fatigue model. Consequently, it is expected that the developed model will bridge the gap between viscoelastic fracture and continuum damage mechanics, and provide better cracking performance predictions of asphalt mixtures. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000335

Investigation on sintering mechanism of nanoscale tungsten powder based on atomistic simulation / Amitava Moitra in Acta materialia, Vol. 58 N° 11 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 3939–3951 Titre : Investigation on sintering mechanism of nanoscale tungsten powder based on atomistic simulation Type de document : texte imprimé Auteurs : Amitava Moitra, Auteur ; Sungho Kim, Auteur ; Seong-Gon Kim, Auteur Année de publication : 2011 Article en page(s) : pp. 3939–3951 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Atomistic  simulation  Nanoscale  Tungsten  Grain  boundary  misalignment  Neck  growth Résumé : Atomistic simulations focusing on sintering of crystalline tungsten powders at the submicroscopic level are performed to shed light on the processing on the nanoscale powders. The neck growth and shrinkage were calculated during these sintering simulations, making it possible to extend these results to the evolution of global physical properties that occurs during sintering. The densification and grain growth during sintering were calculated with variations in temperature, pressure, particle configuration and crystalline misalignment between particles. These findings lay the foundation for a virtual approach to setting the processing cycles and materials design applicable to nanoscale powders. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001886 [article] Investigation on sintering mechanism of nanoscale tungsten powder based on atomistic simulation [texte imprimé] / Amitava Moitra, Auteur ; Sungho Kim, Auteur ; Seong-Gon Kim, Auteur . - 2011 . - pp. 3939–3951. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 3939–3951 Mots-clés : Atomistic  simulation  Nanoscale  Tungsten  Grain  boundary  misalignment  Neck  growth Résumé : Atomistic simulations focusing on sintering of crystalline tungsten powders at the submicroscopic level are performed to shed light on the processing on the nanoscale powders. The neck growth and shrinkage were calculated during these sintering simulations, making it possible to extend these results to the evolution of global physical properties that occurs during sintering. The densification and grain growth during sintering were calculated with variations in temperature, pressure, particle configuration and crystalline misalignment between particles. These findings lay the foundation for a virtual approach to setting the processing cycles and materials design applicable to nanoscale powders. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001886