Influence of timber moisture content on wave time-of-flight and longitudinal natural frequency in coniferous species for different instruments

Llana, Daniel F.; Íñiguez-González, Guillermo; Martínez, Roberto D.; Arriaga, Francisco J.

doi:10.1515/hf-2017-0113

Cited by 20 publications

(7 citation statements)

References 15 publications

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“…One possible explanation is that the hammer and accelerometer of the MTG instrument were too close to the edge of a board during the measurements on the smaller boards for optimum performance, although this cross-section is still within the permitted size range of the instrument (CEN 2009). Llana et al (2018a) found linear relationships between SWV obtained using five different devices on four pine species and MC measured on timber boards. The relationships were different above or below FSP, but the prediction of timber properties was not affected by MC.…”

Section: Influence Of Pre-sortingmentioning

confidence: 81%

Predicting structural timber grade-determining properties using acoustic and density measurements on young Sitka spruce trees and logs

et al. 2018

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In Ireland, most structural timber from Sitka spruce (Picea sitchensis[Bong.] Carr.) is machine graded into C16 strength class. However, timber from early thinnings is mostly used for non-structural applications. There is an increased demand for structural timber, and timber from young trees could contribute to wood supply. However, this timber has lower mechanical properties than mature timber. In order to pre-sort the resource for structural application of wood from thinning, the possibilities of acoustic and density (D) measurements on young trees and logs have been investigated. The stress wave velocity (SWV) and pin penetration depth (PD) were measured on standing trees, which were then felled and cut into 10-m-long logs and subsequently into 3-m-long logs. Fundamental frequency was measured on logs. Finally, the logs were processed into boards, which were tested in accordance with EN 408 to obtain modulus of elasticity (MOE) in bending, bending strength (BStr) and D. The results showed good relationships between timber properties and acoustic and D measurements. Models for predicting grade properties of timber from thinnings are presented. Pre-sorting of young Sitka spruce trees and logs helped obtain higher C16 yields.

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Section: Influence Of Pre-sortingmentioning

confidence: 81%

Predicting structural timber grade-determining properties using acoustic and density measurements on young Sitka spruce trees and logs

et al. 2018

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“…Hassan et al (2013) determined the dynamic modulus of elasticity as 11,000 N/mm 2 in small-clear Scots pine samples. In studies conducted on structural Scots pine timbers, Montero et al (2015) found 9,680 N/mm 2 at 12% moisture content, Arriaga et al (2012) found 10,900 N/mm 2 , and Llana et al (2018) found approximately 11,100 N/mm 2 . Güntekin et al (2013Güntekin et al ( , 2014 found the dynamic modulus of elasticity as 9,840 N/mm 2 using the vibration method for Turkish red pine structural timbers at 27.1% moisture content.…”

Section: Resultsmentioning

confidence: 97%

Visual and machine strength gradings of Scots and red pine structural timber pieces from Türkiye

Kurul,

2024

BioRes

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Scots (Pinus sylvestris L.) and red pine (Pinus brutia Ten.) structural timbers (540 pieces) from Türkiye were first visually graded according to TS 1265 (2012). Then, non-destructive tests were conducted using vibration and time of flight (ToF) methods, followed by destructive tests on a four-point bending test setup according to EN 408 (2012). The vibration method showed a higher correlation than ToF with strength and stiffness. The dynamic modulus of elasticity (MOEd) obtained by the vibration method was 12.3% and 15.4% lower in Scots and red pine, respectively, compared to the ToF method. Mechanical testing determined local MOE was 14% and 15% higher than global MOE for Scots and red pine, respectively. An alternative formula to the existing conversion formula in EN 384 (2018) was derived. The average bending strength of red pine was 7% higher than Scots pine. For visual strength grading, local and global MOE in Scots pine, class 1, 2, and 3 structural timbers were assigned to C35, C27, and C22, respectively. Red pine was assigned to C40, C27, and C24 for local MOE and C35, C24, and C22 for global MOE. In machine strength grading, the grade combination was C40-C30-C22-C16-R for both species. The best results were achieved in settings where vibration method and local MOE were used together. Machine strength grading achieved higher efficiency than visual strength grading.

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“…Most of the research works related to the MC influence on NDT results focused on acoustic and resonance techniques [28][29][30][31][32]. Most of them found a more substantial MC influence below than above the fiber saturation point (FSP) [33][34][35][36][37]. Fewer research works dealing with MC influence on NDT-punctual techniques (probing, drilling, and coring) were found [38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Wood Density and Moisture Content Estimation by Drilling Chips Extraction Technique

et al. 2020

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The novelty of this study is the development of an accurate wood moisture content (MC) estimation method based on a relatively brand-new, non-destructive testing technique (drilling chips extraction). The method is especially important in the assessment of existing timber structures, where non-destructive testing (NDT) results are affected by wood MC and should be adjusted to a reference MC, usually 12%. In the assessment of timber structures, it is not possible to determine MC by oven drying method and this should be estimated. Electrical resistance and capacitance are the conventional methods used for MC estimation. This research work aims to present an accurate MC estimation method based on the drilling chips extraction technique. For that, 99 specimens (90 × 65 × 38 mm3) from three softwood and hardwood species covering a wide range of densities (from 355 to 978 kg m−3) were tested after conditioning at five different MCs (5%, 10%, 15%, 20%, 25%). The Wood Extractor device based on the drilling chips extraction technique was used. The mass of the chips collected (drilling residue) from each drill was recorded. The results show that the MC of the chips extracted was statistically significantly different than the MC of the specimen and cannot be directly used as MC determination. However, the chips MC can be used as an estimator of specimen MC with high determination coefficients (R2 from 71% to 86%). As the main result, models to estimate density directly adjusted to a reference 12% MC from the wet and dry mass of chips extracted were developed with an R2 of 98%. In sum, the drilling chips extractor is a dependable and straightforward method to estimate MC and density from only one measurement. Density adjusted to a reference 12% MC can be directly estimated from a single model.

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Influence of timber moisture content on wave time-of-flight and longitudinal natural frequency in coniferous species for different instruments

Cited by 20 publications

References 15 publications

Predicting structural timber grade-determining properties using acoustic and density measurements on young Sitka spruce trees and logs

Predicting structural timber grade-determining properties using acoustic and density measurements on young Sitka spruce trees and logs

Visual and machine strength gradings of Scots and red pine structural timber pieces from Türkiye

Wood Density and Moisture Content Estimation by Drilling Chips Extraction Technique

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