A model of anisotropic swelling and shrinking process of wood

Yamamoto, Hiroyuki; Sassus, F.; Ninomiya, Manabu; Gril, Joseph

doi:10.1007/s002260000074

Cited by 80 publications

(71 citation statements)

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“…The MFA x shrinkage plot did not show a clear trend (Figure 2). The works of Meylan (1968) and Yamamoto et al (2001) reported a strong influence of the MFA on the wood shrinkage for a range from 30° to 50°. In this study, the maximum value of MFA was 24° which explained the quasi-absence of relationship between MFA and shrinkages.…”

Section: Correlations Among Wood Traitsmentioning

confidence: 98%

Correlations among microfibril angle, density, modulus of elasticity, modulus of rupture and shrinkage in 6-year-old Eucalyptus urophylla × E. grandis

Hein

Silva

Brancheriau

2013

Maderas, Cienc. tecnol.

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The cellulose microfibril angle (MFA) in the cell wall is known to have major effects on wood stiffness and shrinkage. However, its influence on juvenile wood traits is not fully understood, especially in Eucalyptus. The aim of this study was to evaluate the relationships among MFA, density (ρ), dynamic modulus of elasticity (E), modulus of rupture (MOR), and shrinkage (δ) in 6-year-old Eucalyptus urophylla × E. grandis. Small clear specimens (L 410 mm x R 25 mm x T 25 mm) were cut from central boards for the determination of E and MOR. Cubic samples (25 mm³) were removed after the dynamic and static tests to evaluate ρ and δ. MFA was finally measured by X-ray diffraction on small strips coming from the cubic samples. A quasi-absence of statistical link was found for MFA -δ and MFA -ρ (R²<0.20). The parameter ρ/MFA was used to estimate E (R²=0.66) and MOR (R²=0.37). In a next step, the additive and interaction effects were investigated using multiple linear regressions with a forward selection method. The property E was found to be linked only with the additive effects of ρ and 1/MFA (R²=0.76). The additive and interaction effects were all significant for MOR (R²=0.54). This study showed that a general model including both additive and interaction effects should be used for the prediction of the modulus of elasticity and the modulus of rupture.

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Section: Correlations Among Wood Traitsmentioning

confidence: 98%

Correlations among microfibril angle, density, modulus of elasticity, modulus of rupture and shrinkage in 6-year-old Eucalyptus urophylla × E. grandis

Hein

Silva

Brancheriau

2013

Maderas, Cienc. tecnol.

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“…However, for reaction woods, both CW and TW, drying shrinkage has much higher values, often larger than 1% (numerous references in [74]). The reason for this has long been identified for CW: shrinkage occurs in the matrix, and, due to the large microfibril angle, is substantially redirected into the longitudinal direction [81,94]. For TW, this high shrinkage appears paradoxical, because cellulose microfibrils, in view of their abundance, stiffness and axial orientation, should prevent longitudinal shrinkage.…”

Section: Drying Shrinkagementioning

confidence: 99%

Critical review on the mechanisms of maturation stress generation in trees

Alméras

Clair

2016

J. R. Soc. Interface.

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Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering.

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“…Dans cette perspective, la complexité structurale évidente des essences feuillues impliquera de substituer à certains changements d'échelle envisagés ici des modèles parfois moins simplistes [37].…”

Section: Conclusion Et Perspectivesunclassified

Paramètres structuraux et/ou ultrastructuraux facteurs de la variabilité intra-arbre de l’anisotropie élastique du bois

Guitard

Gachet

2004

Ann. For. Sci.

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Résumé -La simulation de l'anisotropie élastique d'un bois résineux sans défaut est réalisée par empilement de trois échelles de descriptions, faisant passer successivement du niveau de la paroi cellulaire, à celui de chacun des tissus ligneux et enfin au niveau du cerne. Les modèles micromécaniques utilisés à chaque étape restent basés sur la recherche du solide élastique homogène équivalent, par des lois des mélanges simples appliquées à des assemblages série ou parallèle de sous domaines supposés homogènes. Un jeu utile de 17 paramètres réalistes, en regard de données bibliographiques variées, est optimisé sur la base des données caractéristiques élastiques anisotropes du « résineux standard ». L'outil de modélisation est adapté à l'analyse de la sensibilité des propriétés élastiques à la variabilité des paramètres adoptés bien que s'éloignant quelque peu de la stricte réalité ultrastructurale. Une originalité réside dans la schématisation de la paroi cellulaire en une couche unique, renforcée par un squelette de microfibrilles, dont l'orientation est empruntée à l'angle des microfibrilles de la sous couche S 2 ; le caractère rigidifiant du squelette, par comparaison à une structure renforcée par des fibres parallèles traduit les renforcements transverses de la paroi, le plus souvent imputés aux sous couches S 1 et S 3 . bois / anisotropie / élasticité / micromécanique / ultrastructureAbstract -Structural and/or ultrastructural parameters governing the variability inside the tree of the elastic anisotropy of wood. Three levels of modelling are introduced to simulate the elastic anisotropy of solid clear softwood, from the cell wall level, via wooden tissues, to the annual ring level. The micro-mechanical models used, at each step, are based on the homogeneous elastic equivalent solid method. Quite simple mixture laws are used for series or parallels assembling of two assumed homogeneous media. 17 realistic parameters are identified by optimisation on the base of given orthotropic elastic properties of the "standard softwood". The modelling tool allows analysing the sensibility of elastic parameters to the variability of internal structural parameters even if it doesn't express quite the ultrastructural reality. One of the originalities is include in cellular wall schematization by a unique layer, reinforcing by a microfibrille skeleton, in which the microfibrillar orientation belongs to S 2 layer. The stiffening of this skeleton, in front of a structure with parallels fibers, represents the cell walls tranverses reinforcements generally assigned to S 2 and S 3 layers.wood / anisotropy / elasticity / micro mechanics / ultrastructure

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A model of anisotropic swelling and shrinking process of wood

Cited by 80 publications

References 0 publications

Correlations among microfibril angle, density, modulus of elasticity, modulus of rupture and shrinkage in 6-year-old Eucalyptus urophylla × E. grandis

Correlations among microfibril angle, density, modulus of elasticity, modulus of rupture and shrinkage in 6-year-old Eucalyptus urophylla × E. grandis

Critical review on the mechanisms of maturation stress generation in trees

Paramètres structuraux et/ou ultrastructuraux facteurs de la variabilité intra-arbre de l’anisotropie élastique du bois

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