Predicting oak wood properties using X-ray inspection: representation, homogenisation
and localisation.
 
Part I: Digital X-ray imaging and representation by finite elements

Badel, Éric; Perré, Patrick

doi:10.1051/forest:2002063

Cited by 16 publications

(11 citation statements)

References 16 publications

(14 reference statements)

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“…Changes in MC are accompanied with swelling and shrinkage stresses, which are highly relevant for the application of wood as construction material, because the stresses can induce cracks that decrease the service life of wooden structural members (Niemz 1993). Variations in the magnitude and relation of the swelling coefficients have been observed with respect to tree species, wood density, cellulose microfibril angle, presence of reaction wood, distance from pith, and growth ring width (Kollmann and Côté 1968;May 1978;Quirk 1984;Skaar 1988;Bengtsson 2001;Badel and Perré 2002;Donaldson 2008). However, these studies have been generally conducted on macroscopic wood samples, thus neglecting the variability on the growth ring scale.…”

Section: Introductionmentioning

confidence: 98%

Combination of neutron imaging (NI) and digital image correlation (DIC) to determine intra-ring moisture variation in Norway spruce

et al. 2013

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Abstract:The hygroscopic behavior of wood has a strong influence on its mechanical performance, yet the moisture gradients within the growth ring structure have not been sufficiently investigated. The main challenge is that moisture variations are coupled with strong sample deformation, which complicates the spatial referencing of moist and dry states. In this work, neutron imaging (NI) for the detection of water and digital image correlation (DIC) for the detection of local deformation were combined to calculate the local gravimetric moisture content (MC grav ) and the volumetric moisture content (MC vol ) within single growth rings. Specimens of Norway spruce [Picea abies (L.) Karst.] were exposed to an adsorption-desorption cycle, with relative humidity (RH) steps varying from 0% (oven dry) up to 95% RH. After each acclimatization step, neutron transmission and DIC images were acquired. The local deformations determined by DIC were used to assign the corresponding dry density in the undeformed state to the compartment in a moist state and thus to calculate its MC by NI. No significant MC gradients could be found between earlywood (EW) and latewood (LW) within ± 0.5% accuracy. However, strong density gradients between EW and LW can be directly correlated with MC vol . It appears that the MC in the cell wall is constant regardless of the particular growth ring position.

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Section: Introductionmentioning

confidence: 98%

Combination of neutron imaging (NI) and digital image correlation (DIC) to determine intra-ring moisture variation in Norway spruce

et al. 2013

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“…For several years, we have been presenting the different elements of a complete modelling tool chain. In two previous papers, (Badel and Perré 2002;Perré and Badel 2003), we described a modelling tool that is able to predict the shrinkage/swelling and the elastic properties of oak wood in the transverse directions. This model is based on the description of the actual anatomical structure of the annual ring and takes the microscopic properties of each tissue into account (Badel andPerré 1999, 2001).…”

Section: Introductionmentioning

confidence: 99%

The shrinkage of oak predicted from its anatomical pattern: validation of a cognitive model

Badel

Perré

2006

Trees

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This paper deals with the ability of a scientific strategy to compute the shrinkage behaviour of any oak sample, regardless of its origin, density, growth ring, etc. This approach uses the description of the actual oak structure at the annual ring level (i.e. the spatial organisation of the radial ray-cells, fibre, parenchyma areas and large vessels), to evaluate its shrinkage/swelling and elastic properties in the transverse directions. For the shrinkage properties, computed results were compared with experimental values measured on a set of samples depicting a very large diversity of anatomical patterns. The accuracy of our prediction is about 5% in the tangential direction and 20% in the radial direction, which is much better than statistical models over a wide range of variables. These results are discussed and a few microscopic observations with ESEM allow explanation of anomaly points of behaviour to be formulated. Such good results could allow this approach to be used to study the influence of growing conditions or of global changes upon physical wood properties

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“…In particular, each node situated at the boundary must have its "periodic" equivalent. This requirement has been fulfilled when constructing the partitioned boundaries of the unit cell contours (see Part I, [5]). …”

Section: Computational Aspectsmentioning

confidence: 99%

“…After image segmentation, the contours are extracted and smoothed. The length of each contour segment can be chosen as an input parameter (mesh refinement) for the mesh generator (see Part I, [5]). …”

Section: Computational Aspectsmentioning

confidence: 99%

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Predicting of oak wood properties using X-ray inspection: representation, homogenisation and localisation. Part II: Computation of macroscopic properties and microscopic stress fields

Perré¹,

Badel²

2003

Ann. For. Sci.

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-This paper is the second part of a comprehensive approach that allows the elastic and shrinkage properties of oak to be determined from the properties of the anatomical tissues and the spatial distribution of those tissues, obtained by a high resolution digital X-ray imaging device. The computation of the macroscopic properties employs a 2-D numerical tool, called MorphoPore, that utilises periodic homogenisation over the representative volume. The paper starts with the derivation of the mechanical formulation and analyses the effect of mesh refinement on the overall solution quality. Thereafter, a first example is presented that depicts the effect of fibre proportion and fibre zone shape on the macroscopic properties using a virtual anatomical pattern and a second example uses finite element meshes built from actual patterns coming from two positions of the same tree, just before and just after thinning the forest stand. The approach presented in this research allows the increase of rigidity and shrinkage coefficients due to the increase of the annual ring width to be quantified. Finally, two localisation problems are proposed in which the micro-stress fields are computed from the macroscopic loading. The first case assumes that no macroscopic stress field exists (free shrinkage configuration), whereas the second assumes that the macroscopic displacement is constrained along one direction (drying configuration).wood / homogenisation / modelling / numerical computation Résumé -Utilisation de l'imagerie X pour la prédiction du bois de chêne : représentation, homogénéisation et localisation. Partie II : Calcul des propriétés macroscopiques et des champs de micro-contraintes. Cet article est la deuxième partie d'une approche complète qui permet de prédire les propriétés élastiques et de retrait du chêne à partir des propriétés des tissus qui le composent et de leur distribution spatiale décrite par un système d'imagerie X de haute résolution spatiale. Le calcul des propriétés macroscopique est effectué par homogénéisation de milieux périodiques sur un volume élémentaire représentatif à partir d'un code numérique 2-D, appelé MorphoPore. Ce papier commence par la présentation de la formulation mécanique. Viennent ensuite quelques considérations sur l'effet du raffinement du maillage numérique. À l'aide de plans ligneux virtuels, le premier exemple d'application montre l'effet de la proportion des fibres et de la forme de zone de fibres sur les propriétés macroscopiques. Le deuxième exemple utilise deux plans ligneux réels, provenant du même arbre. La seconde zone produite juste après éclaircie, a un accroissement annuel très important. Notre approche permet de quantifier l'augmentation des rigidités et des coefficients de retrait. Enfin, deux exemples de localisation sont proposés. Cette démarche permet le calcul des champs de micro-contraintes à partir du chargement macroscopique de la structure. Le premier cas considère l'absence de contrainte macroscopique (retrait libre) tandis que le deuxième considère...

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Predicting oak wood properties using X-ray inspection: representation, homogenisation and localisation. Part I: Digital X-ray imaging and representation by finite elements

Cited by 16 publications

References 16 publications

Combination of neutron imaging (NI) and digital image correlation (DIC) to determine intra-ring moisture variation in Norway spruce

Combination of neutron imaging (NI) and digital image correlation (DIC) to determine intra-ring moisture variation in Norway spruce

The shrinkage of oak predicted from its anatomical pattern: validation of a cognitive model

Predicting of oak wood properties using X-ray inspection: representation, homogenisation and localisation. Part II: Computation of macroscopic properties and microscopic stress fields

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