TAILIEUCHUNG - Báo cáo lâm nghiệp: "Viscoelastic behaviour of green wood across the grain. Part II. A temperature dependent constitutive model defined by inverse method"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: "Viscoelastic behaviour of green wood across the grain. Part II. A temperature dependent constitutive model defined by inverse method" | Ann. For. Sci. 62 2005 823-830 INRA EDP Sciences 2005 DOI forest 2005088 823 Original article Viscoelastic behaviour of green wood across the grain. Part II. A temperature dependent constitutive model defined by inverse method Joelle Passard Patrick PERRÉ Laboratory of Wood Science LERMAB UMR 1093 INRA ENGREF Université H. Poincaré Nancy 1 ENGREF 14 rue Girardet 54042 Nancy Cedex France Received 31 July 2004 accepted 31 May 2005 Abstract - This paper proposes a new inverse method to identify Kelvin s elements simultaneously from several creep tests carried out at different temperature levels. The dimensionless formulation derived for this approach allows thermally activated Kelvin s elements to be used on non-isothermal tests. For each studied species and each material direction four different tests are analysed simultaneously to define the parameters of the constitutive model. Each test comprises a linear increase in temperature a plateau at the desired temperature 65 C 85 C 105 C and 120 C respectively and a final cooling period. The paper ends up with a comprehensive viscoelastic characterisation of oak and spruce in radial and tangential directions over a temperature range spreading from 40 C to 120 C. Five Kelvin s elements were required for spruce and four elements for oak. Such models are intended to be used in the simulation of wood processing operations such as drying steaming thermal treatment. wood viscoelastic Kelvin s element thermal activation constitutive model inverse method Résumé - Comportement viscoélastique du bois vert dans le plan transverse. Partie II un modèle de comportement dependant de la temperature defini par methode inverse. Cet article propose une nouvelle méthode inverse capable d identifier des éléments de Kelvin en analysant simultanément plusieurs essais de fluage. Chaque test comporte trois phases une montée linéaire en température un palier à la température voulue 65 C 85 C 105 C et 120 C respectivement et une phase de .

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