Thèse soutenue

Identification de la variabilité des rigidités du bois à l'intérieur de l'arbre par la méthode des champs virtuels : application au P. pinaster dans le plan LR
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Accès à la thèse
Auteur / Autrice : José Xavier
Direction : Fabrice Pierron
Type : Thèse de doctorat
Discipline(s) : Mécanique
Date : Soutenance en 2007
Etablissement(s) : Paris, ENSAM
Partenaire(s) de recherche : autre partenaire : Arts et Métiers ParisTech. Centre d'enseignement et de recherche (Châlons-en-Champagne)

Mots clés

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Résumé

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In this work, an inverse approach for the identification of the LR stiffness parameters of maritime pine (P. Pinaster) wood within the stem has been investigated. It is based on the ap- plication of the virtual fields method (VFM) to a rectangular specimen loaded with the Iosipescu fixture. This test has been designed in order to involve several in-plane stiffness components. The displacement fields have been measured by the grid method. The strain fields have been reconstructed from the measured displacement fields using a polynomial approximation scheme. The approach has been validated both numerically and experimentally. Two specimen configurations with grain at 0◦ and 45◦ have been compared. With the 0◦ configuration, only the Q11 and Q66 (longitudinal and shear stiffnesses) parameters have been identified with acceptable dispersion. The grain rotation of 45◦ has generated a redistribution of the strain fields allowing a better iden- tification, namely for the Q22 (radial or transverse stiffness) parameter. The latter has been used in a subsequent study aiming at investigating the radial variability of the stiffnesses within the stem. It has been found that both Q22 and Q66 decrease from the pith to about the middle radius of the stem and increase afterwards to the outmost positions.