Improving strength grading of timber by grain angle measurement and mechanical modeling |
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Authors: | Joffrey Viguier Arnaud Jehl Robert Collet Laurent Bleron Fabrice Meriaudeau |
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Institution: | 1. Université de Lorraine, ENSTIB/LERMAB, 27 rue Philippe SEGUIN, BP1041, F-88051 Epinal Cedex 9, Francejoffrey.viguier@univ-lorraine.fr;3. LaBoMaP, Groupe Matériaux et Usinage Bois, Arts &4. Métiers ParisTech, rue Porte de Paris, F-71250 Cluny, France;5. Université de Lorraine, ENSTIB/LERMAB, 27 rue Philippe SEGUIN, BP1041, F-88051 Epinal Cedex 9, France;6. UMR 5158 uB-CNRS, Le2i, IUT du Creusot, 12 rue de la Fonderie, F-71200 Le Creusot, France |
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Abstract: | AbstractTimber strength grading has become a major issue in the European Union during the last years, due to the introduction of the Eurocode 5 and all its related standards. Currently, the most performing strength grading machines are able to locally detect the boards’ knots sizes and positions and interpret this information through adapted grading models. The best lead to improve their accuracy seems to be the introduction of new information about the boards and adapt the mechanical model to take them in account. Small grain angle causes high reduction of clear wood's mechanical properties; local value of slope of grain appears to be of high interest. The aim of this study is to quantify the additional accuracy that grain angle information can bring to an optical scanner used as a strength grading machine. A specific grading model has been developed accordingly, and the results obtained for different machine/model/loading combinations are presented. These results show that slope of grain measurement can significantly improve the accuracy of the optical scanner, for both modulus of elasticity and modulus of rupture estimations. |
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Keywords: | Grain angle spruce strength grading X-ray |
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