Variation of Drying Strains between Tangential and Radial Directions in Asian White Birch

Fu, Zhihao; Zhao, Jun; Yeli, Yang; Cai, Yingchun

doi:10.3390/f7030059

Cited by 13 publications

(16 citation statements)

References 15 publications

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“…These results confirmed the MC effect under loading on MS strains. The same conclusion was reported by Rice and Youngs (1990) and Fu et al (2016), who confirmed that MS strain is a function of moisture change and increases with decreased moisture content. Table 2 shows the MS strain results and mechano-sorption coefficient (m) for each perpendicular direction measured and load level.…”

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confidence: 76%

Perpendicular Mechano-Sorptive Strains during Moisture Desorption from Eucalyptus nitens Specimens

et al. 2016

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aThe purpose of this paper was to determine the mechano-sorptive strains produced during desorption of moisture from Eucalyptus nitens specimens, from a perspective of modeling wood drying stresses. Eucalyptus nitens samples were tested in the radial and tangential directions. The mechano-sorptive strain was measured by cantilever bending during desorption. The runs were performed in a conditioning chamber at constant low temperature and variable equilibrium moisture content. Four load levels were considered for testing. The results showed that the mechano-sorptive strain during desorption of moisture was proportional to applied stress and reached the maximum value in the tangential direction. Also, the mechano-sorption coefficient depended on wood orientation and reached the maximum value of 5.46 × 10 -2 in the tangential direction. Bio-Bio, Av. Collao 1202, 4081112, Concepción, Chile; *Corresponding author: nattperez@gmail.com Keywords INTRODUCTIONChile has approximately 0.74 million hectares of Eucalyptus plantations available for industrial processing, and approximately 30% contain Eucalyptus nitens (INFOR 2015). E. nitens plantations are mainly distributed in the VIII and X regions, and they are the fastest growing species in Chile. E. nitens plantations grow as fast as 77 m 3 /ha/year (INFOR 1989), and they are well adapted to the cold winter conditions in Southern Chile (INFOR 2004).The volume of wood from E. nitens available in Chile for commercial use is estimated to reach 7 million m 3 per year in 2040 (INFOR 2015). This abundance is an incentive for processing this species into solid wood products for domestic and international markets. Unfortunately, the development of commercial solid products from this species is currently limited by the sawlog performance due to longitudinal growthstrains (Valencia et al. 2011) and drying difficulties due to their propensity of surface and internal checking, collapse, and higher transversal shrinkage (Ananías et al. 2009(Ananías et al. , 2014Sepúlveda et al. 2016). A more comprehensive understanding of the drying properties of E. nitens is essential for the successful processing of this species in commercial solid wood products.E. nitens is highly prone to internal checking (Leandro et al. 2008;Rebolledo et al. 2013). E. nitens of lower density tends to be associated with higher internal intra-ring PEER-REVIEWED ARTICLE bioresources.com Pérez et al. (2016). "Mechano-sorptive strain," BioResources 11(4), 8277-8284. 8278checking. The drying of E. nitens solid wood is also limited by collapse propensity (Ananías et al. 2009(Ananías et al. , 2014Sepúlveda et al. 2016). During the initial stages of drying, the surface layers shrink and exert compressive stresses on the core-wood, inducing drying stresses. These behaviors change with moisture content and temperature variations during drying. The drying stresses cause permanent and transitory deformations on the wood, i.e., warping and internal checking. For E. nitens, Pérez et al. (2013) observed that drying stres...

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Perpendicular Mechano-Sorptive Strains during Moisture Desorption from Eucalyptus nitens Specimens

et al. 2016

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“…Cutting wood log into thin disks is an advantageous to better understand the evolution of drying stresses because of the possibility to compare drying strains between tangential and radial directions [28]. Shrinkage ratio is an important parameter that can be used to characterize the performance of wood drying.…”

Section: Bd and Transverse Shrinkagementioning

confidence: 99%

Transverse shrinkage variations within tree stems of Melia azedarach planted in northern Vietnam

Duong

Matsumura

2018

J Wood Sci

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This study quantified variations within tree stems in tangential shrinkage (α T), radial shrinkage (α R), and tangential/radial shrinkage ratio (α T /α R) of Melia azedarach grown in two different sites in northern Vietnam. The overall values of α T , α R , and α T /α R were 7.05%, 4.38%, and 1.64, respectively. The variation pattern in α T and α R was found to increase gradually from pith to bark and this trend was similar on both sites. In radial direction, the α T /α R decreased significantly from 10 to 50% of the radial length from pith before approaching a constant value toward the outside. The transverse shrinkage variation with height was very small and without statistical significance. There were strong positive relationships between transverse shrinkage and basic density (BD). This implies that the selection for high wood density may lead to increase wood transverse shrinkage. In addition, the α T and α R had significant positive linear relationships with both acoustic wave velocity (V L) and dynamic modulus of elasticity of log (DMOE log). This result suggests that it might be possible to sort lumber with large transverse shrinkage by stress wave method for M. azedarach planted in northern Vietnam.

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“…During drying, shrinkage varied in different parts of the specimen due to the non-uniform distribution of MC and the differences in grain direction. For wood discs, the shrinkage in the tangential direction was restrained by the radial direction, and the shrinkage in lower MC parts was retrained by the higher MC parts (Fu et al 2016b). Therefore, the shrinkage strain was not just induced by only the loss of MC, but also due to the restrained drying stresses.…”

Section: Effect Of Pre-steaming On Restrained Shrinkage Strain and Frmentioning

confidence: 99%

Effects of saturated vapor pre-steaming on drying strain in Asian White Birch: Experimentation and modelling

Avramidis

Zhao

et al. 2019

Maderas, Cienc. tecnol.

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The effect of low pressure saturated vapor pre-steaming on restrained shrinkage strain, mechanosorptive creep and the distribution of moisture content was investigated during conventional drying of wood discs. Mechano-sorptive creep was furthermore modelled by artificial neural network theory with five inputs, i.e., pre-steaming and drying temperatures, wood moisture content, relative humidity and distance from the pith. Results revealed that, pre-steaming partly reduced the variation of moisture content distribution along radial direction, increased restrained shrinkage strain in heartwood and decreased in sapwood and slightly decreased the mechano-sorptive creep. The neural network model provided reasonable prediction results, namely, the coefficient of determination for training, validation and test sets greater than 0,95.

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Variation of Drying Strains between Tangential and Radial Directions in Asian White Birch

Cited by 13 publications

References 15 publications

Perpendicular Mechano-Sorptive Strains during Moisture Desorption from Eucalyptus nitens Specimens

Perpendicular Mechano-Sorptive Strains during Moisture Desorption from Eucalyptus nitens Specimens

Transverse shrinkage variations within tree stems of Melia azedarach planted in northern Vietnam

Effects of saturated vapor pre-steaming on drying strain in Asian White Birch: Experimentation and modelling

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