Indentation behavior of metal–ceramic multilayers at the nanoscale / G. Tang in Acta materialia, Vol. 58 N° 6 (Avril 2010)  

Public ISBD [article]  inActa materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2033–2044 Titre : Indentation behavior of metal–ceramic multilayers at the nanoscale : Numerical analysis and experimental verification Type de document : texte imprimé Auteurs : G. Tang, Auteur ; Y.-L. Shen, Auteur ; D.R.P. Singh, Auteur Année de publication : 2011 Article en page(s) : pp. 2033–2044 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Nanoindentation Multilayers Nanocomposites Finite element analysis Plastic deformation Résumé : The behavior of aluminum/silicon carbide nanolayered composite in response to nanoindentation loading is studied. The effects of heterogeneity on the deformation fields, as well as the hardness and elastic modulus obtained from indentation, are investigated using finite element analysis. Attention is also devoted to correlating the numerical results with experimental deformation and damage features. The model uses an explicit layered structure within the axisymmetric framework. It is found that the nanolayered composite results in unique deformation patterns. Significant tensile stresses can be generated locally along certain directions, which offers a mechanistic rationale for the internal cracking observed experimentally. The unloading process also leads to an expansion of the tension-stressed area, as well as continued plastic flow in parts of the aluminum layers. Comparisons of hardness and indentation-derived modulus between modeling and experiments also point to the importance of incorporating the detailed geometric features when performing indentation analyses. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008258 [article] Indentation behavior of metal–ceramic multilayers at the nanoscale : Numerical analysis and experimental verification [texte imprimé] / G. Tang, Auteur ; Y.-L. Shen, Auteur ; D.R.P. Singh, Auteur . - 2011 . - pp. 2033–2044. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2033–2044 Mots-clés : Nanoindentation Multilayers Nanocomposites Finite element analysis Plastic deformation Résumé : The behavior of aluminum/silicon carbide nanolayered composite in response to nanoindentation loading is studied. The effects of heterogeneity on the deformation fields, as well as the hardness and elastic modulus obtained from indentation, are investigated using finite element analysis. Attention is also devoted to correlating the numerical results with experimental deformation and damage features. The model uses an explicit layered structure within the axisymmetric framework. It is found that the nanolayered composite results in unique deformation patterns. Significant tensile stresses can be generated locally along certain directions, which offers a mechanistic rationale for the internal cracking observed experimentally. The unloading process also leads to an expansion of the tension-stressed area, as well as continued plastic flow in parts of the aluminum layers. Comparisons of hardness and indentation-derived modulus between modeling and experiments also point to the importance of incorporating the detailed geometric features when performing indentation analyses. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008258

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The loader problem / G. Tang in Journal of the operational research society (JORS), Vol. 61 N° 5 (Mai 2010)  

Public ISBD [article]  inJournal of the operational research society (JORS) > Vol. 61 N° 5 (Mai 2010) . - pp. 840–848 Titre : The loader problem : formulation, complexity and algorithms Type de document : texte imprimé Auteurs : G. Tang, Auteur ; F. Chen, Auteur ; Cheng, T. C. E., Auteur Année de publication : 2010 Article en page(s) : pp. 840–848 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Loader problem Integer programming Logistics NP-hard Algorithms Index. décimale : 001.424 Résumé : In this paper we consider a new transportation model, called the loader problem, which is frequently encountered by third-party logistics service providers in practice. It is a tactical staff-planning problem with the objective of minimizing the total labour cost of staffing a sufficient number of loaders on a given fleet of trucks that serve a given set of customer sites. We formulate the problem as an integer program and show that it is strongly NP-hard. We then consider two special cases of the loader problem that occur in certain practical situations, and propose polynomial and pseudo-polynomial time algorithms for solving these cases. We also propose a linear programming relaxation-based random rounding algorithm for the general problem and report the computational results of the algorithm. DEWEY : 001.424 ISSN : 0361-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v61/n5/abs/jors200955a.html [article] The loader problem : formulation, complexity and algorithms [texte imprimé] / G. Tang, Auteur ; F. Chen, Auteur ; Cheng, T. C. E., Auteur . - 2010 . - pp. 840–848. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 61 N° 5 (Mai 2010) . - pp. 840–848 Mots-clés : Loader problem Integer programming Logistics NP-hard Algorithms Index. décimale : 001.424 Résumé : In this paper we consider a new transportation model, called the loader problem, which is frequently encountered by third-party logistics service providers in practice. It is a tactical staff-planning problem with the objective of minimizing the total labour cost of staffing a sufficient number of loaders on a given fleet of trucks that serve a given set of customer sites. We formulate the problem as an integer program and show that it is strongly NP-hard. We then consider two special cases of the loader problem that occur in certain practical situations, and propose polynomial and pseudo-polynomial time algorithms for solving these cases. We also propose a linear programming relaxation-based random rounding algorithm for the general problem and report the computational results of the algorithm. DEWEY : 001.424 ISSN : 0361-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v61/n5/abs/jors200955a.html

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