Modélisation du comportement mécanique des bois de structures par densitométrie X et imagerie laser

Abstract : Since the introduction of the Eurocode 5 and its related standards, lumber strength grading has become a major issue for the European wood industry. The main objective and technological limitation of this grading type stands in the estimation of the boards’ mechanical properties, especially their elasticity modulus (MOE) and strength (MOR). The machines currently considered as the most effective are able to locally detect the boards’ knots positions and geometries, and to interpret this data through adapted models. However, these models barely adapt to various stresses distributions, and are not able to take in account other kinds of singularities. Slope of grain around knots, especially, considerably decrease sound wood’s mechanical properties, but its influence on full-size boards had never been quantified. Through this study, we developed an original behavior model, called “Equivalent Profile”, allowing taking in account both stresses distribution and any kind of singularity. We have thus evaluated this model’s performances, considering knottiness data obtained by X-Rays densitometry and slope of grain’s acquired by laser imaging, by comparison between estimated and destructively measured mechanical properties values. We showed, on one hand, that our model provides high performances, without taking in account slope of grain, compared to established methods’ ones. On the other hand, slope of grain data actually allows a substantial improvement of mechanical properties’ estimation accuracy.
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Arnaud Jehl. Modélisation du comportement mécanique des bois de structures par densitométrie X et imagerie laser. Matériaux. Paris, ENSAM, 2012. Français. ⟨NNT : 2012ENAM0008⟩. ⟨tel-01682225⟩

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