Wood and Fiber Science (E-Journal)
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Effects of Long-Term Outdoor Exposure on Properties of I-joists
Full text linkI-joists manufactured using wood composites are intended for dry service condition. Situations arise where I-joists are exposed to excessive weather conditions. This exposure to moisture can degrade structural properties of I-joists. In a follow-up to a previous published study (King et al 2014) looking at the short-term exposure to moisture (138 d), this study extends the exposure days further to 1351 d (approx. 3.5 yr) to gain an insight into property changes and fine-tune the degradation model presented by King et al (2014). Long-term exterior exposure was associated with continued declines in maximum load and deflection at maximum load, but the rate of property loss decreased as the exposure period was extended. Bending failure modes shifted back from web buckling to shear type failures at the web-web and web-flange joints
Ductility and Brittleness in small clear notched S-P-F beams
Full text linkBecause wood has both brittle and ductile behaviors, the impact of stress concentration around notches is difficult to quantify. This research used the bending stiffness to strength ratio as a means of evaluating stress concentrations in the tension and compression faces of small clear spruce-pine-fir beams. The bending strength and stiffness behavior of wood and wood composites is of particular interest in ladder rails, laminated beams, and structural cross laminated timber, and other heavy timber construction. It was found that rectangular notches up to half of the beam depth located on the tension face reduced the bending strength by 10.5%. The drop in in ductility, as measured by MOE/MOR, was significantly higher, up to 52%. Beams loaded with the notch on the compression face had no statistically significant change in MOR; however, ductility dropped by as much as 30%.
Salvaged lumber for Structural Mass Timber Panels: Manufacturing and Testing
Full text linkPortland, OR, was the first US city to implement a deconstruction ordinance in 2016. Although salvaged lumber can have a high demand, the market for small-sized lumber from deconstructed dwellings is near saturation. New applications for this material are required for market development, industry diversification, and increasing deconstruction practices. Mass timber products such as cross-laminated timber (CLT) could be a new market for this material, but presently there is minimal information qualifying the performance of mass timber panels made with salvaged lumber. Three, full-sized 3-ply experimental layups, with varying amounts of salvaged/recycled wood content, were manufactured and tested to characterize panel properties. Manufacturing processes and testing methods followed ANSI/APA PRG 320-2018; Standard for Performance Rated Cross-Laminated Timber. Each panel layup had three replicates for nine panels in total. Panels measured 1.1 m by 2.3 m by 3 plys, and test results were used to calculate the effective flatwise bending moment resistance ((FbS)eff), effective flatwise bending stiffness ((EI)eff) effective shear stiffness in flatwise bending ((GA)eff), flatwise shear resistance (Vs), percent wood failure (WF%), and percent delamination (Delamination %). Results were compared with E3 grade 3-ply CLT panels made in the United States and indicated that salvaged lumber could be used as feedstock for mass timber panels in core layers or all layers. All panel layups passed benchmarks for (FbS)eff and (EI)eff benchmarks with values greater than PRG320. Panels having salvaged lumber in core layer also met Vs benchmarks. Furthermore, all panels passed examination for WF% but struggled to meet delamination requirements. Possibilities exist for better performance if panels were made in a commercial setting. This research shows salvaged lumber has promise for manufacturing structural CLT, but more research and a larger samples size is needed to verify findings
INDENTATION COEFFICIENT AND INDENTATION BEHAVIOR OF BAMBOO
Full text linkBamboo hardness test standards are not available. The study aimed to develop a new method of testing bamboo indentation hardness. With the V-shaped prismatic head, bamboo rings with different lengths were tested. The V-shaped indentation coefficient (IC) was defined. The results showed that the IC had a good correlation with compression strength. The V-shaped IC increased with the increase in the longitudinal height of the bamboo pole, and the variance analysis showed significant differences in different axial directions of the same bamboo ring. In addition, the correlation between density and IC is good. The V-shaped IC can be applied in bamboo gr
EFFECT OF ALKALI TREATMENT ON THE TENSILE PROPERTIES OF GRAPE CANE FIBERS BY INTEGRATING DIGITAL IMAGE CORRELATION METHOD
No full textThe objective of this study was to investigate tensile properties of two grape cane fibers, namely, outer bark (OB) and inner bark (IB). The cane is a necessary annual by-product from vineyards and is produced at approximately 36 million tons yearly around the world, which currently has no substantial commercial utilization. Grape cane fibers were subjected to an alkali treatment, at different concentrations, to separate the fibers from the cane. Moreover, two displacement methods such as system compliance (Cs) and digital image correlation (DIC) were performed to determine Young’s modulus of the samples, and the results were compared. The OB fibers had better overall properties than IB fibers. The effect of the treatment concentrations (1, 3, 5, and 7 wt% of sodium hydroxide) and gage lengths (10, 25, and 40 mm) on the tensile properties was not consistent for both fiber types. The DIC method consistently yielded greater tensile modulus of the samples than the Cs method for OB fibers.
Effect of Coating Thickness on Sound Absorption Property of Four Wood Species Commonly Used for Piano Soundboards
Full text linkEffects of polyurethane (PU) coating thicknesses (0.15, 0.30, 0.45, and 0.60 mm) on sound absorption coefficients of four wood species were investigated using the standing wave ratio method with an input sound vibration frequency range set between 125 and 4000 Hz. Wood species of four specific gravity (SG) levels were Korean spruce, European spruce, Sitka spruce, and Picea brachytyla. Experimental results indicated that PU coating can significantly increase sound absorption coefficients of higher SG species such as Sitka spruce and Picea brachytyla in all tested frequency levels, but this significant increase was not observed in lower SG species such as Korean and European spruces when tested in the frequency range from 800 to 2000 Hz. Effects of coating thickness on sound absorption coefficients of four evaluated species were found to interact with wood SG values and input sound vibration frequency ranges. Specifically, coating 0.30-mm-thick PU on Korean and European spruces tends to result in significantly lower sound absorption coefficients among the ones coated with four evaluated thicknesses when tested at the frequency less than 800 Hz, but PU coating thickness resulting in lower sound absorption coefficients on Sitka spruce and Picea brachytyla was 0.15 mm. Sitka spruce and Picea brachytyla coated with 0.30- and 0.6-mm-thick PU had lower sound absorption coefficients when tested at the frequency ranging from 1000 to 2000 Hz. When tested at the frequency greater than 2500 Hz, sound absorption coefficients of four coated species increased as coating thickness increased from 0.30 to 0.60 mm with an increment of 0.15 mm, but these four species coated with three thicker PU had significantly lower sound absorption coefficients than the ones coated with 0.15-mm-thick PU. The uncoated higher SG species tended to have lower sound absorption coefficients than uncoated lower SG ones when tested in the frequency ranging from 500 to 4000 Hz, but the differences were not found when tested under the frequency less than 400 Hz. Coating four species with different thicknesses of PU could alter their SG effects on their sound absorption coefficients
Fiber Morphology, Chemical Composition, and Pulping of Nine Introduced Poplar Clones Grown in Beijing, China
Full text linkEvaluating the wood properties of poplar clones to be used in fast-growing and high-yield plantation and select superior clones are critical to increase both quantity and quality of wood production. This study determined the fiber morphology, chemical composition and pulping of nine introduced poplar clones after six growing seasons and assessed their suitability for pulping and papermaking. Results showed that the fiber morphological differences among nine clones were not obvious. Fiber with length less than 1.0 mm accounted for 91.7% of the total fibers which were mainly short. Taro had longer and thinner fibers with the largest length-width ratio, followed by Bellatto, whereas Lambro owned the shortest and thickest fiber with a small length-width ratio. Neva had the Runkel ratio much high as 1.0, which was larger than that of other eight clones. From the point of view of chemical composition, Taro contained low content of ash, cold/hot water-soluble content, benzene ethanol-soluble content, and lignin, but higher content of holocellulose. 1% sodium hydroxide-soluble and pentosan contents were 20.47% and 22.62% respectively, on average; thus Taro can be suggested as good-quality industrial material applied in pulping and papermaking. On the contrary, Bellotto got imperfect overall performance, which was considered comprehensively before selection.
Technical Note: Properties of Wood from Frost-Tolerant Eucalyptus Planted in Brazil
No full textThe study of the technological characteristics of wood is of great importance as it provides information that may help to direct its best use. It is also useful in forest breeding programs and in the choice of which species to plant. Traditionally, the most planted tree in Brazil is the hybrid Eucalyptus grandis x Eucalyptus urophylla. The planting of Eucalyptus in Brazilian cold regions has intensified in recent years, and this and other species of the genus have also been used for this. Wood basic density, fiber dimensions, chemical composition, and higher heating value (HHV) of Eucalyptus benthamii,Eucalyptus dunnii, and Eucalyptus saligna, all species with a tolerance to frost, were analyzed. Basic densities, all greater than 460 kg/m3, were not significantly different among species. E. dunnii had the longest fiber ().98 mm), the highest holocellulose content, and the lowest lignin content, showing its potential for pulping. E. Benthamii and E. Salignatogether have higher lignin content with greater HHV, and so are more indicated for energy. Total extractive and ash content were high, but there were no significant differences among the species.