Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs

Larsen, Finn; Ormarsson, Sigurdur

doi:10.1515/hf-2012-0149

Cited by 16 publications

(8 citation statements)

References 20 publications

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“…Zhan and Avramidis separated MS creep from viscoelastic creep strain and determined the relative magnitude of each drying strain under different drying temperatures [11,12]. Larsen and Ormarsson reported on the moisture-induced strains and tensile strength in a tangential direction under different climatic conditions based on finite element modeling [13,14]. That is the most written about topic for a long time, but no research has been published on the difference of drying strains between the tangential and radial directions.…”

Section: Introductionmentioning

confidence: 99%

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

Zhao

Yeli

et al. 2016

Forests

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Abstract:In this study, wood disks of 30 mm in thickness cut from white birch (Betula platyphylla Suk) logs were dried at a constant temperature (40˝C). The drying strains including practical shrinkage strain, elastic strain, viscoelastic creep strain and mechano-sorptive creep were measured both tangentially and radially. The effects of moisture content and radial position on each strain were also discussed qualitatively. Overall, the difference of the practical shrinkage strain between the tangential and radial directions was proportional to the distance from the pith. The tangential elastic strain and viscoelastic creep strain were higher than these strains in a radial direction, and they all decreased with the decrease of moisture content. Additionally, there were opposite mechano-sorptive creep between tangential and radial directions.

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Section: Introductionmentioning

confidence: 99%

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

Zhao

Yeli

et al. 2016

Forests

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“…4 represent the creep compliance changes over 20 min for 13 temperature levels (10°C intervals in the range 30-150°C). The curves showed the expected response from isothermal creep segments: increasing creep compliance with time and temperature for each specimen irrespective of grain orientation [2,7,21]. There were differences in compliance among the specimens with three grain orientations.…”

Section: Resultsmentioning

confidence: 92%

Application of time–temperature superposition principle to Chinese fir orthotropic creep

Peng

Jiang

et al. 2017

J Wood Sci

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The application of time-temperature superposition principle (TTSP) to orthotropic creep in dry Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) was investigated through a sequence of short-term tensile creep for longitudinal (L), radial (R), and tangential (T) specimens in the temperature range of 30-150°C. A visual assessment for the validity of TTSP was carried out by applying the approximated complex plane (ACP). The results showed that TTSP was well matched for R and T specimens using horizontal shift factor to construct master curves. As for L specimen, an additional vertical shift factor was applied to construct a smooth master curve, owing to the temperaturedependent compliance. Based on the application of ACP, the creep model governed by a power law was proposed to successfully depict the master curve for each main anatomy direction. The present study partially provided the firsthand data in verifying the applicability of TTSP of the orthotropic viscoelasticity of Chinese fir wood, and successfully constructed the rheological model to predict the orthotropic creep response. More importantly, the result can function as the base to the structural safety designs for the engineering structures of Chinese fir in practice.

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“…The actual drying shrinkage strains include elastic strain, viscoelastic creep strain, and mechanical adsorption creep strain. The actual drying shrinkage strain obtained when drying the product to target moisture content could accurately determine the machining allowance [16][17][18]. Free drying shrinkage of wood relies upon negligible drying stress of small thin specimens during slow drying (desorption).…”

Section: Introductionmentioning

confidence: 99%

Laws Governing Free and Actual Drying Shrinkage of 50 mm Thick Mongolian Scotch Pine Timber

Zhu

Zhao

Wan-hui

et al. 2021

Forests

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The relationships between free shrinkage and actual shrinkage of different layers in Mongolian Scotch pine (Pinus sylvestris var. mongolica Litv.) were explored to provide basic data for the further study of drying shrinkage properties. The free shrinkage coefficients at different temperatures and the actual shrinkage strain of each layer were examined under conventional drying. The results showed high precision of free drying shrinkage of corresponding layers of thin small test strips in each layer of sawn timber. The free shrinkage increased linearly as moisture content declined. At the same temperature, the free shrinkage coefficient reached the largest values for the first layer (above 0.267%), while the smallest values were recorded for the ninth layer (below 0.249%). Except for the ninth layer, the free shrinkage coefficients in width directions of other representative layers decreased as temperature increased. At constant temperature, the difference in free shrinkage coefficient of test materials in the length direction of sawn timber was small for the first layer, but slightly larger and changed irregularly in the fifth and ninth layer direction. At the end of conventional drying, the plastic deformation of each layer in the early stage of drying showed a reducing trend or even reversal due to the effects of reverse stress and later damp heat. In sum, these findings look promising for future optimization of wood drying process.

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Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs

Cited by 16 publications

References 20 publications

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

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

Application of time–temperature superposition principle to Chinese fir orthotropic creep

Laws Governing Free and Actual Drying Shrinkage of 50 mm Thick Mongolian Scotch Pine Timber

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