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1. Modelling the growth stress in tree branches: eccentric growth vs. reaction wood

Author

Van Rooij, Arnoul, Badel, Eric, Barczi, Jean-François, Caraglio, Yves, Almeras, Tancrede, and Gril, Joseph

Subjects
Archaeology, CC1-960, Science
Abstract

This work aims to model the mechanical processes used by tree branches to control their posture despite their increasing weight loading. The two known options for a branch to maintain its orientation are the asymmetry of maturation stress, including reaction wood formation, and eccentric radial growth. Both options can be observed in nature and influence the stress distribution developed in the branch each year. This so-called "growth stress" reflects the mechanical state of the branch. In this work, a growth stress model was developed at the cross-section level in order to quantify and study the biomechanical impact of each process. For illustration, this model was applied to branches of two 50-year-old trees, one softwood Pinus pinaster, and one hardwood Prunus avium (wild cherry tree), both simulated with the AmapSim discrete element software. For the wild cherry tree, the computed outputs highlighted that the eccentricity of radial growth seems to be as efficient as the formation of reaction wood to maintain postural control despite the increasing gravity. For the pine tree, eccentric radial growth appears to be less efficient than the formation of reaction wood. But although it does not necessarily act as a relevant lever for postural control, it greatly modifies the profile pattern of mechanical stress and could provide mechanical safety of the branch. This work opens experimental perspectives to understand the biomechanical processes involved in the formation of branches and their mechanical safety.

Published
2023
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2. Tree growth forces and wood properties

Author

Thibaut, Bernard and Gril, Joseph

Subjects
Archaeology, CC1-960, Science
Abstract

Living wood in the tree performs a muscular action by generating forces at the sapwood periphery and residual strains in dead sapwood fibres. Dissymmetric force generation around the tree trunk is the motor system allowing movement, posture control and tree reshaping after accidents. Rather young trees are able to restore the verticality of their trunk after accidental rotation of the soil-root system due to wind or landslide, leading to typically curved stems shape. The very high dissymmetry of forces for the motor action is associated with the occurrence of reaction wood on one side of the inclined stem during many successive years. A method to reconstitute this biomechanical history from observations after tree felling, on either green or dry wood, is discussed. A selection of 17 trees from 15 different species (13 different families), tropical and temperate, hardwoods and softwoods, were selected and peripheral residual strains were measured in situ before felling, on 8 positions for each stem. Matched wooden rods were sawn and measured for their mechanical and physical properties in the green and dry states, allowing the estimation of tree growth stress, i.e., the force created by the living wood. It was possible to build easy-to-use conversion coefficients between the growth stress indicator (GSI), measured in situ by the single hole method, and growth strain and growth stress with the knowledge of basic density and green longitudinal elastic modulus. Maturation strain, specific modulus (as a proxy of micro-fibril angle) and longitudinal shrinkage are properties independent from basic density, whose variation among species was very large. For the whole range of compression wood, normal wood and tension wood, strong relationships between these 3 properties were observed, but together no single model, based on cell-wall microfibril angle only, could be defined. Growth forces are the product of 4 parameters: ring width, basic density, basic specific modulus and maturation strain, all of them being the result of wood formation. Thanks to the wide range of wood types and species, simple and highly significant formulas were obtained for the relationship between basic and dry density, green and dry longitudinal modulus of elasticity, basic and dry specific modulus. To estimate ring width in the green state from values in dry state, radial shrinkage needs to be measured afterwards on dry specimens. Maturation strains is less accurately linked to late measurements on dry wood, but longitudinal shrinkage offers a rather good solution for an estimation provided that the wood type (softwood, hardwood with-G layer, hardwood without G-Layer) is known.

Published
2021
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7. Revisiting the notion of 'resonance wood' choice: a decompartementalised approach from violin makers' opinion and perception to characterization of material properties' variability

Author

Carlier, Capucine, Alkadri, Ahmad, Gril, Joseph, and Brémaud, Iris

Subjects
Physics - Classical Physics
Abstract

This work aims to improve our understanding of the resonance wood and to investigate the interactions between their physical-mechanical properties, natural variability, and the violin makers' ways of choosing their materials. In order to identify the luthiers' practices and opinions, a socio-technical survey was conducted. Physical, vibrational, and visual/structural characteristics of the resonance wood obtained from several provenances with a variety of quality grades were also determined. Finally, these two approaches were completed by a psychosensory evaluation to compare the measurements that we have conducted with the perception and qualification of wood by the violin makers.

Published
2019

12. Wood Science for Conservation of Cultural Heritage – Braga 2008

Author

Gril, Joseph

Abstract

COST Action IE0601 "Wood Science for Conservation of Cultural Heritage" (www.woodculther.org) aims to improve the conservation of European wooden cultural heritage objects, by fostering research and interaction between researchers in various fields of wood science, conservators of wooden artworks, scientists from related fields. These proceedings contain the papers presented in the 2nd International Conference held in Braga (Portugal) 5-7/11/2008, dealing with themes such as material properties, biological degradation, characterization and measurement techniques, conservation, structures. This conference was patronized by the European Society for Wood Mechanics (ESWM), an informal body promoting wood mechanics in Europe by regular organisation of meetings through running COST Actions.

Published
2022
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21. Role of the Gelatinous Layer (G-Layer) on the Origin of the Physical Properties of the Tension Wood of Acer sieboldianum

Author

Yamamoto, Hiroyuki, Abe, Kentaro, Arakawa, Yoshiharu, Okuyama, Takashi, and Gril, Joseph

Subjects
Physics - Classical Physics
Abstract

The tension wood (TW) properties of a 70 year-old Acer sieboldianum Miq were analyzed by using the G-fiber model which was proposed in our previous paper. The roles of the G-layer on the origins of (1) a high large tensile growth stress, (2) a large longitudinal Young's modulus, and (3) a high longitudinal drying shrinkage in the tension wood xylem were discussed on the basis of the simulations using the G-fiber model. The results suggest that the G-layer generates a high tensile stress in the longitudinal direction during the xylem maturation; the longitudinal Young's modulus of the green G-layer becomes significantly higher than that of the lignified layer; furthermore, the G-layer tends to shrink extraordinarily higher than that of the lignified layer during the moisture desorption., Comment: J Wood Sci, in press (accepted April 12, 2004)

Published
2005
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22. Mod\'{e}lisation des d\'{e}formations de maturation de la fibre

Author

Sassus, François, Alméras, Tancrède, Gril, Joseph, and Yamamoto, Hiroyuki

Subjects
Physics - Classical Physics
Abstract

The generation mechanism of growth strains is investigated theoretically by developing an elastic analysis of a wood cell viewed as a composite tube, with layers composed of a ligno-cellulosic material of varying composition and microfibrillar orientation. For each layer, the kinetics of induced strain is assumed synchronous with that of rigidification. In this case, variations of polymer behaviour concomitant with orientation must be invoked to account for observed variations of the growth strain., Comment: to be published in Cahiers Scientifiques du Bois

Published
2005

23. Swelling of acetylated wood in organic liquids

Author

Obataya, Eiichi and Gril, Joseph

Subjects
Physics - Chemical Physics, Condensed Matter - Materials Science
Abstract

To investigate the affinity of acetylated wood for organic liquids, Yezo spruce wood specimens were acetylated with acetic anhydride, and their swelling in various liquids were compared to those of untreated specimens. The acetylated wood was rapidly and remarkably swollen in aprotic organic liquids such as benzene and toluene in which the untreated wood was swollen only slightly and/or very slowly. On the other hand, the swelling of wood in water, ethylene glycol and alcohols remained unchanged or decreased by the acetylation. Consequently the maximum volume of wood swollen in organic liquids was always larger than that in water. The effect of acetylation on the maximum swollen volume of wood was greater in liquids having smaller solubility parameters. The easier penetration of aprotic organic liquids into the acetylated wood was considered to be due to the scission of hydrogen bonds among the amorphous wood constituents by the substitution of hydroxyl groups with hydrophobic acetyl groups., Comment: to be published in J Wood Science (Japanese wood research society)

Published
2005
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24. Shrinkage of cane (Arundo donax L.) II Effect of drying condition on the intensity of cell collapse

Author

Obataya, Eiichi, Gril, Joseph, and Perré, Patrick

Subjects
Condensed Matter - Materials Science, Physics - Classical Physics
Abstract

To improve the drying method in the manufacture of woodwind reeds, green canes (Arundo donax L.) were dried under various humidity-temperature conditions and the intensity of cell collapse was evaluated from the swelling due to steaming involving the recovery of collapse. At 30 C, the intensity of collapse was increased by slower drying. It was considered that: 1) slower drying resulted in higher sample temperature in the early stage of drying to increase the collapse; 2) rapid drying stiffened the surface of sample and such "shell" prohibited the following collapse; 3) slower drying i.e. longer loading of liquid tension caused more remarkable and/or frequent viscoelastic yields of cells. Consequently the intensity of collapse increased when the cane was dried from its waxy outer surface or in the presence of node: both of them retarded the drying. On the other hand, higher drying temperature caused greater intensity of collapse in spite of faster drying. It was suggested that the thermal softening of cane cells leads to easier yield of the cell wall, at the same time the rapid drying does not allow the recovery of collapse after the disappearance of free water. These results indicated that faster drying at lower temperature is preferable for drying cane with less collapse., Comment: Will be published in J. Wood Sci. (Japanese wood research society) - follows part I: J. Wood Sci. 50 : 295-300

Published
2005
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25. Studies on European beech (Fagus sylvatica L.). Part 1: Variations of wood colour parameters

Author

Liu, Shengquan, Loup, Caroline, Gril, Joseph, Dumonceaud, Olivier, and Thibaut, Bernard

Subjects
Quantitative Biology - Tissues and Organs
Abstract

Colour parameters of European beech were measured using CIELab system. 103 logs from 87 trees in 9 sites were cut into boards to study the variations of wood colour parameters. Both site and tree effect on colour were observed. Patterns of red heartwood occurrence were defined. When excepting red heartwood there was still a highly significant effect of site and tree; differences remained after veneer processing. Axial variations were small, except very near the pith or in red heartwood, suggesting possible early selection at periphery under colour criteria. Red heartwood is darker, redder and more yellow than normal peripheral wood., Comment: to be published in Annals of Forest Science reception 12.8.04; acceptation 15.2.05

Published
2005

26. Reduction of wood hygroscopicity and associated dimensional response by repeated humidity cycles

Author

Esteban, Luis García, Gril, Joseph, De Palacios, Paloma De Palacios, and Casasús, Antonio Guindeo

Subjects
Physics - Classical Physics, Condensed Matter - Materials Science, Quantitative Biology - Tissues and Organs
Abstract

The reduction of wood response to variations of ambient humidity, described as kind of ageing, has been studied from both points of view of moisture uptake and dimensional changes. Clearwood specimens from 3 gymnosperms (Pinus sylvestris L., Pinus pinaster Ait., Pinus insignis Dougl.) and 4 angiosperms (Populus spp., Quercus pyrenaica Willd., Entandrophragma cylindricum Sprague, Chlorophora excelsa Benth. & Hook f.) were subjected to five wet-dry cycles and their moisture content and dimensional changes in radial and tangential direction at three increasing levels of relative humidity (57.6, 84.2 and 90.2%) were measured before and after the treatment. For a given increase of relative humidity, a coefficient of hygroscopic ageing was defined as the relative decrease of moisture uptake, and the coefficient of dimensional ageing as the difference of swelling strain before and after ageing. All species exhibited a clear ageing effect, much stronger in the wet range than in the dry range. Calculation of swelling coefficients suggested that in some cases the relation between swelling strain and moisture content is no longer linear in aged wood., Comment: to be published in Annals of Forest Science

Published
2005

27. Evidence and quantitative evaluation of tensile maturation strain in flax phloem through longitudinal splitting

Author

Almeras, Tancrede, Petrova, Anna, Kozlova, Liudmila, Gril, Joseph, and Gorshkova, Tatyana

Subjects
Biological sciences
Abstract

The stems of flax (Linum usitatissimum L. cv. 'Mogilevsky') contain many gelatinous fibers in their phloem. These fibers are important for the mechanical stability of the plant as well as for industrial applications. Gelatinous fibers are known to have a motor function in the xylem of trees and in many plant organs. This function arises from the so-called maturation strain, i.e., the tendency of the gelatinous layer to shrink during fiber maturation, resulting in a state of residual tensile stress. However, the occurrence of tensile maturation strain in flax phloem fibers remains to be demonstrated, and its magnitude has never been evaluated. Here we present a novel method to highlight and quantify this strain. The method consists in splitting a stem segment longitudinally, and measuring the curvature of the half segments through their opening distance. By using a mechanical model, the maturation strain can be calculated from the curvature, the dimensions of the component tissues, and their elastic properties. The model is validated by the agreement between model predictions and observations. The splitting experiment provides qualitative evidence that flax phloem develops tensile stress during maturation, just as xylem gelatinous fibers do. Calculations enable quantitative estimation of the maturation strain. The magnitude of this strain for the material studied is, on average, -1.5%. Keywords: flax, bast fibers, gelatinous fibers, tension, stem splitting, maturation strain. Les tiges du lin (Linum usitatissimum L. cv. 'Mogilevsky') contiennent plusieurs fibres gelatineuses dans leur phloeme. Ces fibres sont importantes pour la stabilite mecanique de la plante de meme que pour ses applications industrielles. Les fibres gelatineuses sont connues pour avoir une fonction motrice dans le xyleme des arbres et dans plusieurs organes vegetaux. Cette fonction provient de ce que l'on appelle une tension de maturation, c'est-a-dire la tendance de la couche gelatineuse a se contracter lors de la maturation des fibres, donnant lieu a un etat de contrainte de traction residuelle. Toutefois, l'existence d'une tension de maturation par traction dans les fibres du phloeme du lin reste a demontrer, et son ampleur n'a jamais ete evaluee. Les auteurs presentent ici une nouvelle methode qui permet de mettre en evidence et de quantifier cette tension. La methode consiste a scinder un segment de la tige de maniere longitudinale et a mesurer la courbure des demi-segments par la distance de leur ouverture. En utilisant un modele mecanique, la tension de maturation peut etre calculee a partir de la courbure, des dimensions des tissus constituants et de leurs proprietes elastiques. Le modele est valide par la concordance entre les predictions du modele et les observations. L'experience de scission fournit une preuve qualitative que le phloeme du lin developpe une contrainte de traction lors de la maturation, tout comme le font les fibres gelatineuses du xyleme. Les calculs rendent possible une estimation quantitative de la tension de maturation. L'ampleur de cette tension pour le materiel etudie est de -1,5% en moyenne. [Traduit par la Redaction] Mots-cles : lin, fibre du liber, fibres gelatineuses, tension, division de la tige, tension de maturation., Introduction Flax plants, like other fiber crops, have straight standing stems with a high height to width ratio (Goudenhooft et al. 2019). The ability of such long but narrow stems [...]

Published
2020
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30. Introduction

Author

Barnett, J. R., Gril, Joseph, Saranpää, Pekka, Wimmer, Rupert, Series editor, Gardiner, Barry, editor, Barnett, John, editor, Saranpää, Pekka, editor, and Gril, Joseph, editor

Published
2014
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33. Some aspects of beech biomechanics: juvenile wood properties, sapwood pre-stress and growth forces

Author

Jullien, Delphine, Liu, Shengquan, Loup, Caroline, Gril, Joseph, Thibaut, Bernard, Bois (BOIS), Laboratoire de Mécanique et Génie Civil (LMGC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Anhui Agricultural University [Hefei], Herbier MPU - Université de Montpellier (MPU), Université de Montpellier (UM), Institut Pascal (IP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA), Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), and CNRS K. C. Wong post-doctoral program and China Scholarship Council

Subjects
Beech, [SPI]Engineering Sciences [physics], Radial variation, Growth stress, [SDV]Life Sciences [q-bio], Wood properties, Variability
Abstract

The building of a tree is the result of wood growth through successive division, expansion and maturation of living cells at the periphery of the trunk and branches. During this process, diameter growth is combined with sapwood pre-stress to allow posture control by the generation of growth forces in the living wood cells. These mechanical aspects of tree building can be characterised at each peripheral position by parameters describing the amount of material produced, wood rigidity and the strain induced by the maturation process. In-situ assessment of maturation strains at the trunk periphery of beech trees, combined with laboratory measurements of ring width (RW), wood density (D) and wood specific modulus (SM), was used to examine biomechanical aspects of juvenility corresponding to young stages of the tree, as well as the correlation or trade-off between sapwood pre-stressing and the generation of forces in the living wood layer used to control tree posture. The radial variations of RW, D and SM, averaged over 86 trees, were close to the “typical radial pattern” of juvenile wood for softwood plantation trees: decrease in RW and increase in D and SM from pith to bark in the juvenile phase. But D only increased in the very first rings, then remained more or less constant. Furthermore, for all three parameters there were many discrepancies in the pattern of variation between trees and even between plots. This is a good indication that the mechanical juvenility of the wood was more related to the biomechanical conditions experienced by the trees in the young ages than to the age of the tree as such (which is the case for fibre length). The level of pre-stress and posture control forces were strongly dependent on the maturation strain as the first explanatory factor. But pre-stress is independent of RW, whereas posture control force is strongly dependent on this growth parameter. This opens the way to trade-offs between these two biomechanical functions of wood fibres.; La construction d'un arbre est le résultat de la croissance du bois par division, expansion et maturation successives des cellules vivantes à la périphérie du tronc et des branches. Au cours de ce processus, la croissance en diamètre est combinée à la précontrainte de l'aubier pour permettre le contrôle de la posture par la génération de forces de croissance dans les cellules vivantes du bois. Ces aspects mécaniques de la construction des arbres peuvent être caractérisés à chaque position périphérique par des paramètres décrivant la quantité de matière produite, la rigidité du bois et la déformation induite par le processus de maturation. L'évaluation in situ des contraintes de maturation à la périphérie du tronc des hêtres, combinée à des mesures en laboratoire de la largeur des cernes (RW), de la densité du bois (D) et du module spécifique du bois (SM), a été utilisée pour examiner les aspects biomécaniques de la juvénilité correspondant aux jeunes stades de l'arbre, ainsi que la corrélation ou le compromis entre la précontrainte de l'aubier et la génération de forces dans la couche de bois vivant utilisée pour contrôler la posture de l'arbre. Les variations radiales de RW, D et SM, moyennées sur 86 arbres, étaient proches du "schéma radial typique" du bois juvénile pour les arbres de plantation de résineux : diminution de RW et augmentation de D et SM de la moelle à l'écorce dans la phase juvénile. Mais D n'a augmenté que dans les tout premiers cernes, puis est resté plus ou moins constant. En outre, pour les trois paramètres, il existe de nombreuses divergences dans le schéma de variation entre les arbres et même entre les parcelles. Cela indique bien que la juvénilité mécanique du bois était davantage liée aux conditions biomécaniques subies par les arbres dans les jeunes âges qu'à l'âge de l'arbre en tant que tel (ce qui est le cas pour la longueur des fibres). Le niveau de précontrainte et les forces de contrôle de la posture dépendent fortement de la contrainte de maturation, qui est le premier facteur explicatif. Mais la précontrainte est indépendante du RW, alors que la force de contrôle de la posture est fortement dépendante de ce paramètre de croissance. Cela ouvre la voie à des compromis entre ces deux fonctions biomécaniques des fibres de bois.

Published
2023

34. Reversible and irreversible effects of mild thermal treatment on the properties of wood used for making musical instruments: comparing mulberry to spruce

Author

Karami, Elham, Brémaud, Iris, Bardet, Sandrine, Almeras, Tancrede, Guibal, Daniel, Langbour, Patrick, Pourtahmasi, Kambiz, Gril, Joseph, Department of Wood Processing and Biomaterials, (DWPB, CZU Faculty of Forestry and Wood Sciences), Bois (BOIS), Laboratoire de Mécanique et Génie Civil (LMGC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), BioWooEB (UPR BioWooEB), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Université de Montpellier (UM), Département Performances des systèmes de production et de transformation tropicaux (Cirad-PERSYST), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Natural Resources Faculty, University of Guilan, Institut Pascal (IP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA), Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), and Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA)

Subjects
[PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], K50 - Technologie des produits forestiers, Ecology, Musical Instruments, CIELab, Thermal Treatment, Anisotropy, Forestry, Reconditioning, Vibrational Properties, Morus alba, Nature and Landscape Conservation
Abstract

International audience; Thermal treatments can be considered as an accelerated ageing, bringing partly similar changes in properties as naturally aged wood. Thermal treatment was applied on white mulberry (Morus alba L.), a dominant species for making musical instruments from middle-East to Far-East, to investigate the effects on the vibro-mechanical and physical properties of this wood, and the results compared to previously published data on spruce (Picea abies Karst.) as a reference for the soundboard of Western string instruments. Thermal treatment (TT) at 150 °C and 0% of relative humidity was applied to five analogous groups of specimens with five different durations (2.5, 8, 24, 72, 261 hours). Humidity reconditioning of specimens was done to explore the reversibility of TT effects. Physical and vibrational properties such as specific gravity (γ), equilibrium moisture content (EMC), CIELab colorimetric values, specific modulus of elasticity (E'/γ) and damping coefficient (tanδ) in longitudinal (L) and radial (R) directions, have been measured after stabilisation of samples in standard conditions (20 °C, 65% RH), before and after TT and then after reconditioning. Untreated mulberry had a low EMC, very low L/R anisotropy and low E'L/γ, and relatively low tanδ. Weight loss (WL) and CIELab values evolved similarly during TT for mulberry and for previous results on spruce, however, their EMC and vibrational properties were affected differently. This could be explained in part by the low anisotropy of mulberry, and in part by its particular extractives. The parts of irreversible effects, linked to chemical modification or degradation, and of reversible effects, linked to physical configuration, were different between mulberry and spruce. The applied treatments did not bring permanent "improvements" in vibrational properties of mulberry, yet its colour appearance was enhanced.

Published
2022
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35. Timber structures in subtropical climate on design: Bois Duramhen programs for Guadeloupe, Martinique and Guyane

Author

Quistin, Paul, Fournely, Eric, Gril, Joseph, Godi, Gael, Cador, Luc, Lamadon, Thierry, Romana, Laurence, Beauchêne, Jacques, Moutou Pitti, Rostand, Quistin, Paul, Fournely, Eric, Gril, Joseph, Godi, Gael, Cador, Luc, Lamadon, Thierry, Romana, Laurence, Beauchêne, Jacques, and Moutou Pitti, Rostand

Abstract

Mainly due to a lack of information on the local climate and its consequences on timber buildings, and regarding Eurocode standard, French West Indies islands and French Guiana remain considered as a service class 3 (SC3). Based on Meteo France (MF) data and moisture content measurements on more than 300 sites in the three departments, on local surrounding air humidity and temperature, the three programs Bois Duramhen 971 (European Synergîle), 972 and 973 (PACTE) are devoted to give answers on the impact of this climate on soft and tropical woods integrated in traditional or new timber structures. Data acquisition and analysis are described. Measurements are performed during more than one year, they are compared and completed by Meteo France data. The analysis is divided in two phases: equilibrium moisture content (EMC) calculated from HR(%) - T(°C) with NFEN1995-1.1/NA moisture diagram and direct measurement of instantaneous MC. Monitoring approaches are performed on, at least few members of two real buildings. In Guiana, drying element are also monitored in order to analyse this natural drying phase. Results obtained by the different approaches, comparison of measurements, calibration of measurement equipment, led to a wide data base and proposals of mapping have been deduced.

Published
2023

37. Modelling the growth stress in tree branches: eccentric growth vs. reaction wood

Author

van Rooij, A, Badel, Eric, Barczi, Jean-François, Caraglio, Yves, Almeras, Tancrede, Gril, Joseph, Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), Institut Pascal (IP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA), Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Montpellier (UM), Bois (BOIS), Laboratoire de Mécanique et Génie Civil (LMGC), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)

Subjects
[PHYS.MECA.BIOM]Physics [physics]/Mechanics [physics]/Biomechanics [physics.med-ph], growth stress, biomechanics, tree branches
Abstract

This work aims to model the mechanical processes used by tree branches to control their posture despite their increasing weight loading. The two known options for a branch to maintain its orientation are the asymmetry of maturation stress, including reaction wood formation, and eccentric radial growth. Both options can be observed in nature and influence the stress distribution developed in the branch each year. This so-called "growth stress" reflects the mechanical state of the branch. In this work, a growth stress model was developed at the cross-section level in order to quantify and study the bio-mechanical impact of each process. For illustration, this model was applied to branches of two 50-year-old trees, one softwood Pinus pinaster and one hardwood Prunus avium (wild cherry tree), both simulated with the AmapSim discrete element software. For the wild cherry tree, the computed ouputs highlighted that the eccentricity of radial growth seems to be as efficient as the formation of reaction wood to maintain the postural control despite the increasing gravity. For the pine tree, eccentric radial growth appears to be less efficient than the formation of reaction wood. But although it does not necessarily act as a relevant lever for postural control, it greatly modifies the profile pattern of mechanical stress and could provide mechanical safety of the branch. This work opens experimental perspectives to understand the biomechanical processes involved in the formation of branches and their mechanical safety.

Published
2023

38. Time4WoodCraft – the time of wood craftspersons, the time of crafts’ wood – a transdisciplinary exploration

Author

Brémaud, Iris, primary, Alix, Claire, additional, Backes, Bernadette, additional, Cabrolier, Pierre, additional, Čufar, Katarina, additional, Gilles, Nicolas, additional, Grabner, Michael, additional, Gril, Joseph, additional, Matsuo-Ueda, Miyuki, additional, Poidevin, Nelly, additional, Pont, Olivier, additional, and Rooney, Samuel, additional

Published
2023
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39. Hygromechanical Behaviour of a 16th Century Painted Wooden Panel: In-Situ Experiments to Quantify the Mechanical Effect of the Frame and the Cradle

Author

Jullien, Delphine, primary, Dupre, Jean-Christophe, additional, Gauvin, Cécilia, additional, Uzielli, Lucas, additional, Hesser, Franck, additional, Riparbelli, Lorenzo, additional, Mazzanti, Paola, additional, Gril, Joseph, additional, Tournillon, Gilles, additional, Amoroso, Danièle, additional, Hazael Massieux, Philippe, additional, Stepanoff, Pierre, additional, and Bousvarou, Marina, additional

Published
2023
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44. Reduction of wood thermal conductivity by delignification

Author

Chin, Yi Hien, Biwole, Pascal Henry, Moutou Pitti, Rostand, Gril, Joseph, Vial, Christophe, Ouldboukhitine, Salah-Eddine, Gurcel, Benjamin, Institut Pascal (IP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA), Dagard Company, Centre Procédés, Énergies Renouvelables, Systèmes Énergétiques (PERSEE), Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre national de la recherche scientifique et technologique (CENAREST), Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), This work is supported by the French National Research Agency (ANR) and the companyDagard, under « France Relance » plan., GDR 3544 'Sciences du bois', and Prudon, Magalie

Subjects
delignification, wood nanotechnology, [SPI]Engineering Sciences [physics], [SPI] Engineering Sciences [physics], [SPI.MECA.THER]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Thermics [physics.class-ph], Cellulose nanofibrils, thermal conductivity, [SPI.MECA.THER] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Thermics [physics.class-ph]
Abstract

International audience

Published
2022

45. Isothermes de sorption de bois guyanais en relation avec le projet Bois Duramhen 973

Author

Lefranc, Théo, Bontemps, Arthur, Godi, Gaël, Fournely, Eric, Gril, Joseph, Moutou Pitti, Rostand, Beauchêne, Jacques, Lamadon, Thierry, Cador, Luc, Romana, Laurence, Quistin, Paul, Institut Pascal (IP), SIGMA Clermont (SIGMA Clermont)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-SIGMA Clermont (SIGMA Clermont)-Centre National de la Recherche Scientifique (CNRS), Centre national de la recherche scientifique et technologique (CENAREST), Groupe de Technologie des Surfaces et Interfaces [URp2_2] (GTSI), and Université des Antilles (UA)

Subjects
[SPI]Engineering Sciences [physics]
Published
2022

46. Modelling the growth stress in tree branches: impact of different growth strategies

Author

van Rooij, A, Badel, Eric, Barczi, Jean-François, Caraglio, Yves, Almeras, Tancrede, Gril, Joseph, Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Montpellier (UM), Bois (BOIS), Laboratoire de Mécanique et Génie Civil (LMGC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Institut Pascal (IP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), and Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA)

Subjects
[PHYS.MECA.BIOM]Physics [physics]/Mechanics [physics]/Biomechanics [physics.med-ph]
Published
2022

48. Durabilidad natural y estabilidad dimensional de mora blanca (Morus alba L.) para laudes del Medio Oriente

Author

Se Golpayegani, Aida, Thevenon, Marie-France, Bremaud, Iris, Pourtahmasi, Kambiz, and Gril, Joseph

Subjects
Forest products industry
Abstract

Los fabricantes de instrumentos musicales (lauderos) prefieren madera de especies que no solo tengan excelentes propiedades acústicas, sino que además tiendan a mantener su estado natural durante su fabricación y pretratamientos. En este estudio se hicieron pruebas de inmersión en agua, un protocolo común entre los lauderos iraníes, para determinar la durabilidad natural y estabilidad dimensional de la madera de mora blanca (Morus alba L.). La madera de esta especie, la cual es la única que ha utilizado para la fabricación de los laúdes iraníes por más de un siglo, fue probada para determinar su resistencia natural al ataque de hongos y termitas. Los especímenes fueron estudiados para detectar cambios en sus dimensiones durante cuatro meses de inmersión en agua. La madera en estudio, lixiviada o no, mostró muy alta resistencia tanto al ataque de hongos como al de termitas. La remoción gradual de extractivos durante la inmersión resultó en un incremento en la contracción parcial. Se concluyó que, aun cuando la lixiviación en agua no afecta la durabilidad natural, tiende a reducir la estabilidad dimensional de la madera de mora blanca. Palabras clave: estabilidad dimensional, instrumentos musicales, durabilidad natural, Reticulitermes flavipes (ex.santonensis), filtración de agua, morera blanca (Morus alba L.). Instrument makers prefer wood species which not only have excellent acoustical properties, but also tend to keep their natural state when going through preparations and pretreatments. In this study long time water soaking, a common protocol among Iranian lute makers, was used to investigate the natural durability and dimensional stability of White mulberry (Morus alba L.). The wood of white mulberry, which is the only source for making Iranian lutes for more than a century, was examined for its natural resistance towards fungi and termites. Samples were also studied for their dimensional change during four months of water soaking. White mulberry, whether leached or unleached, showed to be a very resistant species towards both termites and fungi. Gradual removal of the extractives during water immersion resulted in an increase in partial shrinkage. It was concluded that water leaching, though not affecting the natural durability, tends to reduce the dimensional stability of white mulberry. Keywords: dimensional stability, musical instruments, natural durability, Reticulitermes flavipes (ex.santonensis), water leaching, white mulberry (Morus alba L.)., Natural durability and dimensional stability of white mulberry (Morus alba L.) for Middle Eastern lutes INTRODUCTION Wood has been the most commonly chosen material for making musical instruments. From ancient [...]

Published
2017
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50. Modelling the growth stress distribution in tree branches: impact of different growth strategies

Author

van Rooij, A, Badel, Eric, Barczi, Jean-François, Caraglio, Yves, Almeras, Tancrede, Gril, Joseph, Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA), Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Montpellier (UM), Bois (BOIS), Laboratoire de Mécanique et Génie Civil (LMGC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Institut Pascal (IP), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), and Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA)

Subjects
[PHYS.MECA.BIOM]Physics [physics]/Mechanics [physics]/Biomechanics [physics.med-ph]
Published
2022

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