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Generalized symmetric formulation of tangential stiffness for nonassociative plasticity / Debasis Deb in Journal of engineering mechanics, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 139 N° 2 (Février 2013) . - pp.105–113. Titre : Generalized symmetric formulation of tangential stiffness for nonassociative plasticity Type de document : texte imprimé Auteurs : Debasis Deb, Auteur ; Kamal C. Das, Auteur ; G. P. Raja Sekhar, Auteur Année de publication : 2013 Article en page(s) : pp.105–113. Note générale : Applied mechanics Langues : Anglais (eng) Mots-clés : Nonassociative  flow  Tangential  stiffness  Initial  stiffness  Plastic  stress  correction Résumé : The behavior of material nonlinearity with nonassociative plastic flow is frequently analyzed for structures made of soil and rock. It is known that for nonassociated plasticity, the elastoplastic tangential stiffness tensor (matrix) is nonsymmetric. In the FEM, this causes inconvenience for solving a system of equations using the Newton-Raphson solution procedure. In this paper, a mathematical transformation was derived for converting the nonsymmetric tangential stiffness tensor (matrix) into a symmetric tensor such that the global system of equations become unconditionally symmetric. A detailed step-by-step procedure of a stress update algorithm using the tangential stiffness method is elaborated in this paper. The paper also compares the results of the tangential stiffness method with those of the initial stiffness method using an illustrative tunnel problem for associative and nonassociative flow conditions and shows the efficacy of the proposed transformation in elastoplastic problems. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000487 [article] Generalized symmetric formulation of tangential stiffness for nonassociative plasticity [texte imprimé] / Debasis Deb, Auteur ; Kamal C. Das, Auteur ; G. P. Raja Sekhar, Auteur . - 2013 . - pp.105–113. Applied mechanics Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 139 N° 2 (Février 2013) . - pp.105–113. Mots-clés : Nonassociative  flow  Tangential  stiffness  Initial  stiffness  Plastic  stress  correction Résumé : The behavior of material nonlinearity with nonassociative plastic flow is frequently analyzed for structures made of soil and rock. It is known that for nonassociated plasticity, the elastoplastic tangential stiffness tensor (matrix) is nonsymmetric. In the FEM, this causes inconvenience for solving a system of equations using the Newton-Raphson solution procedure. In this paper, a mathematical transformation was derived for converting the nonsymmetric tangential stiffness tensor (matrix) into a symmetric tensor such that the global system of equations become unconditionally symmetric. A detailed step-by-step procedure of a stress update algorithm using the tangential stiffness method is elaborated in this paper. The paper also compares the results of the tangential stiffness method with those of the initial stiffness method using an illustrative tunnel problem for associative and nonassociative flow conditions and shows the efficacy of the proposed transformation in elastoplastic problems. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000487