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Bouc–wen-type models with stiffness degradation / Silvano Erlicher in Journal of engineering mechanics, Vol. 134 N°10 (Octobre 2008)

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°10 (Octobre 2008) . - pp. 843–855. Titre : Bouc–wen-type models with stiffness degradation : Thermodynamic analysis and applications Type de document : texte imprimé Auteurs : Silvano Erlicher, Auteur ; Oreste S. Bursi, Auteur Année de publication : 2008 Article en page(s) : pp. 843–855. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Thermodynamics,  Stiffness,  Energy Résumé : In this paper, a thermodynamic analysis of Bouc–Wen models endowed with both strength and stiffness degradation is provided. This analysis is based on the relationship between the flow rules of these models and those of the endochronic plasticity theory with damage, discussed in a companion paper. Using the theoretical framework of that extended endochronic theory, it is shown that an elastic Bouc–Wen model with damage, i.e., without plastic strains, can be formulated. Moreover, a proper definition of the dissipated energy of these Bouc–Wen models with degradation is given and some thermodynamic constraints on the parameters defining the models behavior are emphasized and discussed. In particular, some properties of the energetic linear stiffness degradation rule as well as the so-called pivot rule, well known in the seismic engineering field, are illustrated and commented upon. An improved energetic stiffness degradation rule and a new stiffness degradation rule are proposed. ISSN : 0733-9399 [article] Bouc–wen-type models with stiffness degradation : Thermodynamic analysis and applications [texte imprimé] / Silvano Erlicher, Auteur ; Oreste S. Bursi, Auteur . - 2008 . - pp. 843–855. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°10 (Octobre 2008) . - pp. 843–855. Mots-clés : Thermodynamics,  Stiffness,  Energy Résumé : In this paper, a thermodynamic analysis of Bouc–Wen models endowed with both strength and stiffness degradation is provided. This analysis is based on the relationship between the flow rules of these models and those of the endochronic plasticity theory with damage, discussed in a companion paper. Using the theoretical framework of that extended endochronic theory, it is shown that an elastic Bouc–Wen model with damage, i.e., without plastic strains, can be formulated. Moreover, a proper definition of the dissipated energy of these Bouc–Wen models with degradation is given and some thermodynamic constraints on the parameters defining the models behavior are emphasized and discussed. In particular, some properties of the energetic linear stiffness degradation rule as well as the so-called pivot rule, well known in the seismic engineering field, are illustrated and commented upon. An improved energetic stiffness degradation rule and a new stiffness degradation rule are proposed. ISSN : 0733-9399

Pseudopotentials and loading surfaces for an endochronic plasticity theory with isotropic damage / Silvano Erlicher in Journal of engineering mechanics, Vol. 134 N°10 (Octobre 2008) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 134 N°10 (Octobre 2008) . - pp.832–842. Titre : Pseudopotentials and loading surfaces for an endochronic plasticity theory with isotropic damage Type de document : texte imprimé Auteurs : Silvano Erlicher, Auteur ; Nelly Point, Auteur Année de publication : 2008 Article en page(s) : pp.832–842. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Plasticity  Thermodynamics  Damage  Isotropy Résumé : The endochronic theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this theory and the classical theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the endochronic plasticity theory was modified in order to introduce the effect of damage. In the present paper, a basic endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an endochronic model of plasticity with damage is investigated and an insightful comparison with classical models is made possible. A damage pseudopotential definition allowing a very general damage evolution is given. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A10%288 [...] [article] Pseudopotentials and loading surfaces for an endochronic plasticity theory with isotropic damage [texte imprimé] / Silvano Erlicher, Auteur ; Nelly Point, Auteur . - 2008 . - pp.832–842. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 N°10 (Octobre 2008) . - pp.832–842. Mots-clés : Plasticity  Thermodynamics  Damage  Isotropy Résumé : The endochronic theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this theory and the classical theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the endochronic plasticity theory was modified in order to introduce the effect of damage. In the present paper, a basic endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an endochronic model of plasticity with damage is investigated and an insightful comparison with classical models is made possible. A damage pseudopotential definition allowing a very general damage evolution is given. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A10%288 [...]