Études des contraintes de croissance des arbres sur pied d'eucalyptus grandis et du chêne vert : caractérisation et valorisation sous forme de bois collé

Abstract : The aim of this study is to measure the growth stress indicators (GSI) of the wood of grown Eucalypti and holm oak and to determine the technological properties for the valorization of these two species in the form of glued wood. Three trees of grown Eucalypti and holm oak were studied. Tensile specimens with massive wood and glued wood (end to end and in bevel), and DCB specimens with massive wood and glued wood were prepared. The quality of the assembly is treated by a probabilistic model based on the Weibull's statistical approach permitting to predict the reliability of the glued systems. The GSI, measured in the periphery of the trees, characterize the state of the wood formed in the very last years. The GSI distribution revealed generally that these two species have different behaviours. The grown Eucalyptus and the holm oak present a high nervousness. These obtained characteristics allowed us to classify them in a hard to half-hard wood, nervous, of strong shrinkage and an average rigidity. The massive wood presents a brittle behaviour with a fracture stress of the holm-oak twice bigger than that of the grown eucalyptus , although the glued wood (end to end or beveled) presents a ductile behaviour with a fracture stress almost the same for these two types of assembly. The Weibull coefficient m of the massive wood of these two species is weaker than that of the glued wood. The measurement of the restitution rate of the energy (toughness) of the massive wood and glued wood of grown eucalyptus and holm-oak has been experimentally achieved using the compliance method. The massive wood of these species is stronger than the glued wood. This latter has a higher toughness than that of the glued polyurethane. The average value of the experimentally determined toughness is very close to that calculated by the finite element code CASTEM 2000, which is greater than those found by ASTM and two embedded beams methods. In the massive wood, the crack initiates in the plan of low strength and the types of fracture observed during its propagation are intercellular and transcellular. In the glued wood the crack starts in the glue joint for the holm-oak, and both in the glue and wood for the grown eucalyptus. Whereas, its propagation is always adhesive for the holm-oak and mixed for the grown eucalyptus (alternately in wood and glue).
Document type :
Theses
Complete list of metadatas

Cited literature [18 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01752462
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 1:48:41 PM
Last modification on : Monday, April 16, 2018 - 10:42:48 AM

File

Daya.Abdelmajid.SMZ0615.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01752462, version 1

Collections

Citation

Abdelmajid Daya. Études des contraintes de croissance des arbres sur pied d'eucalyptus grandis et du chêne vert : caractérisation et valorisation sous forme de bois collé. Autre. Université Paul Verlaine - Metz, 2006. Français. ⟨NNT : 2006METZ015S⟩. ⟨tel-01752462⟩

Share

Metrics

Record views

39

Files downloads

50