Determination of elastic properties of latewood and earlywood by digital image analysis technique

Kuo, Tzu-Yu; Wang, Wei-Chung

doi:10.1007/s00226-019-01096-x

Cited by 12 publications

(4 citation statements)

References 26 publications

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“…However, deriving theoretical formulas from elasticity mechanics for the partial compression problem of wood, which is both orthotropic and heterogeneous, presents significant challenges. The FEA approach could be employed to explore the strain distribution of the partial compression test specimens, but this requires the measurement of mechanical properties of earlywood and latewood (Kang et al 2014;Kuo et al 2019), as well as precise identification of the distribution of these wood types within the specimen using techniques such as X-ray computed tomography imaging. Validating strain gauges in partial compression tests of wood remains a task for future research.…”

Section: Errors In Dic System and Strain Gaugementioning

confidence: 99%

Accuracy of digital image correlation system for compressive behaviour of wood

Teranishi,

Matsubara

2024

Preprint

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The digital image correlation (DIC) system is a powerful tool for measuring distributions of displacement and strain on the surface of a specimen. DIC systems are employed not only for homogeneous materials such as metals but also for heterogeneous materials such as wood. Although numerous validations of DIC system accuracy for metallic materials exist, accuracy verification for wood, especially under multiaxial stress conditions, is less common. This study investigated the accuracy of a DIC system equipped with a bilateral telecentric lens on wood (Douglas fir). The accuracy verification in uniaxial stress fields was conducted through full compression testing, while verification in multiaxial stress fields was performed through partial compression testing. Additionally, compression tests on A6063 (aluminium alloy) were conducted to examine the differences in DIC system accuracy between homogeneous and heterogeneous materials. The accuracy of the DIC system was assessed by comparing the results with those obtained from strain gauges. The results from the full compression tests indicate that the accuracy of axial strain measured by the DIC system was comparable for the specimens of A6063 and Douglas fir in the longitudinal (L) direction but was inferior for Douglas fir in the radial (R) direction. Furthermore, the differences in Young’s modulus obtained from the DIC system and strain gauge for the specimens of A6063, Douglas fir (L), and Douglas fir (R) were 2.3%, 2.4%, and 13.7%, respectively. In the partial compression tests, the accuracy of equivalent strain measured by the DIC system in the specimens of Douglas fir (R) was lower than that in A6063, attributable to a high strain gradient in the attachment region of the strain gauge. A novel variable was proposed using the standard deviation of strain to evaluate this strain gradient within the region. This variable demonstrated correspondence to the difference in equivalent strain obtained from the DIC system and the triaxial strain gauge, regardless of the material’s homogeneity or heterogeneity.

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Section: Errors In Dic System and Strain Gaugementioning

confidence: 99%

Accuracy of digital image correlation system for compressive behaviour of wood

Teranishi,

Matsubara

2024

Preprint

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“…Bjurhager et al [13] used DIC technology to compare the elastic moduli of juvenile European aspen and hybrid aspen. Kuo et al [14] used the DIC technology to analyze Poisson's ratio of earlywood and latewood. Li et al [15] employed the DIC technology to measure the modulus of elasticity, shear modulus, and Poisson's ratio of dense balsam fir wood.…”

Section: Introductionmentioning

confidence: 99%

Fine Characterization and Analysis of Drying Strain of the ELM Board via DIC Technology

Liu¹,

Zhu²,

Jin³

et al. 2023

Journal of Renewable Materials

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In this paper, the occurrence and development mechanism of strain on the cross-section during the wood drying is explored. Therefore, strain regularity on the cross-section of 50 mm thickness elm (Ulmus rubra) board at the temperature of 40°C and 80°C is detected via digital image correlation technology. Hence, the difference between tangential and radial strain at surface and core layers was denoted. The results showed that strain distribution in the width direction of the board is uneven. Moreover, a large drying shrinkage strain occurs at the near-core layer, while the maximum strain difference reaches 4.08%. Hence, the surface of the board is cracked along the thickness direction. The radial strain of the board is higher than the tangential strain in the early stage of drying, while these strains are reversed in the later stage of drying. The temperature is related to the difference between the tangential and radial strains of the elm board. These differences at the core layer are larger than those of the surface layer. The conducted research results provide a theoretical basis for process optimization.

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“…Jeong and Park (2016) evaluated orthotropic properties of wood using DIC and achieved good results. Kuo and Wang (2019) used digital image analysis to measure the elastic properties of latewood and earlywood. To sum up, DIC technology has been widely used in the testing of wood mechanics and dry shrinkage properties, but there are few studies on the application of DIC technology in the testing of wood strain variation in the drying process.…”

Section: Introductionmentioning

confidence: 99%

Digital image correlation method for detecting strain in wood drying process

Chai

Cai

et al. 2023

BioRes

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Stress and strain monitoring is of great significance for wood drying. Using digital image correlation (DIC), this study measured displacement and strain changes during wood drying in real time. The results showed that when wood is dried below the fiber saturation point, the difference of the radial and tangential shrinkage ratio gradually increased. An analysis of tangential and radial shrinkage ratio revealed that in the early stage of drying, the tangential and radial shrinkage ratio was relatively flat; in the middle stage of drying, the shrinkage ratio began to gradually increase; and in the later stage of drying, the tangential shrinkage ratio was approximately twice as large as that in the radial direction. Further, regarding the tangential and radial strain distribution, the radial strain distribution was more scattered than that in the tangential direction. The radial strain distribution exhibited compressive strain on both ends of the specimen, and the tensile strain was in the center. The tangential strain distribution was tensile strain on the left side of the specimen and compression strain on the right. Overall, DIC is stable and reliable, and it can be used to monitor well the stress and strain changes during wood drying.

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Determination of elastic properties of latewood and earlywood by digital image analysis technique

Cited by 12 publications

References 26 publications

Accuracy of digital image correlation system for compressive behaviour of wood

Accuracy of digital image correlation system for compressive behaviour of wood

Fine Characterization and Analysis of Drying Strain of the ELM Board via DIC Technology

Digital image correlation method for detecting strain in wood drying process

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