Growth stresses, end splitting and sawing distorsions in Eucalyptus from plantation

End splits, distorsions and cracks during sawing frequently depreciate the quality of Eucalypts solid wood products from fast growth plantations. These defects are mainly due to the release of growth stresses when processing. Experimental data underscore a close relation between the level of growth strains and an index which allows to quantify the severity of end splits. However, this relation depends simultaneously on the material splitting property in the naturel weakness plane RL and on the apparent splitting property; this splitting property depends on the grain angle. When sawing, modifications of the field of self-balanced stresses in a standing tree can generate distorsions of wood. These distorsions can be modelized using basic concepts of strength of materials, applied to long length beams according the axial direction. Tests in order to open Eucalypts logs in quarters has allowed to establish a relation between sawing distorsions and growth strains measured on the surface of logs before sawing. The elaboration of a model taking into accourt radial variations of the longitudinal modulus of elasticity and the circumferential dissymmetry of growth strains has allowed to obtain a good adjustment between modelized values and measured values.

Bibliographic Details

Main Authors:	Baillères, Henri, Fournier-Djimbi, Meriem, Gérard, Jean, Thibaut, Bernard
Format:	conference_item biblioteca
Language:	eng
Published:	FMPA
Subjects:	K50 - Technologie des produits forestiers, Eucalyptus, propriété mécanique, http://aims.fao.org/aos/agrovoc/c_2683, http://aims.fao.org/aos/agrovoc/c_4683,
Online Access:	http://agritrop.cirad.fr/390995/
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