Wood and Fiber Science (E-Journal)
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GRAIN ANGLE EFFECTS ON ACOUSTIC EMISSION CHARACTERISTICS OF SOUTHERN YELLOW PINE COLUMNS UNDER COMPRESSION
No full textThis study investigated the influence of wood grain angle (0, 10, 20, 30, 45, 60, 75, and 90 degrees) on acoustic emission (AE) characteristics of southern yellow pine columns subjected to compressive loading. Four AE parameters considered were counts, cumulative counts, count rate, and amplitude. The main conclusion was that AE cumulative counts versus time curves can be characterized with three distinct stages in terms of AE count rates: initiation, growth, and acceleration. The initiation stage had a constant mean count rate of 0.33 counts/s compared to the growth stage mean count rate of 19.10 counts/s, while the acceleration stage had a mean count rate of 608.40 counts/s. Within each stage, count rates increased as grain angle increased from 0 to 30 degrees, then dropped as grain angle further increased to 90 degrees. Maximum AE counts and total cumulative AE counts all increased as grain angle increased from 0 to 30 degrees and decreased as grain angle further increased to 90 degrees. Higher AE amplitudes were observed in the yield and failing stages of tested wood columns according to their stress-strain curves plotted together with their corresponding amplitude-time curves. Maximum amplitude increased as grain angle increased from 0 to 20 degrees, then had a decreasing trend as grain angle increased to 45 degrees, followed by an increasing trend as grain angle increased to 75 degrees. These differences in AE characteristics suggested that AE “signatures” in terms of AE signals do exist for timber materials when subjected to compressive loading
Evaluation of flame retardant impregnation in perforated Hinoki (Chamaecyparis obtusa) plywood: Flame retardant impregnation in perforated Hinoki plywood
No full textRecently, perforated plywood has become widely used as an indoor sound absorber. Flame retardant treatment is essential for utilization of wood materials as indoor building materials. Among the various flame retardant treatment methods, we focused on pressure impregnation of water-soluble phosphate flame retardant (WPFR) on commercial Hinoki (Chamaecyparis obtusa) plywood. Perforation rates were 0.06, 0.1, 0.3, and 1.7%, and impregnation times were 30, 60, and 90 min. Then, we evaluated the impregnation effect according to the plywood perforation frequency and impregnation time using Pearson's coefficient correlation analysis and multi-linear regression analysis. The higher were the perforation frequency and impregnation time, the greater was the impregnation effect
Effect of drying of different light hardwood tropical timber species on durability against Coptotermes curvignathus Holmgren under laboratory and field tests
Full text linkThe effects of drying temperature and duration on the durability of Lagerstroemia sp. and Cinnamomum sp. against subterranean termites, Coptotermes curvignathus, were evaluated in no-choice and choice laboratory tests as well as in the aboveground test. Samples measuring 25 mm × 25 mm × 6 mm and 100 mm × 40 mm × 20 mm were dried in an oven at three different temperatures: 60°C, 80°C, and 100°C for two different time periods: 10 and 15 d. In comparison between the control sample and the treated sample, the control sample showed the highest MC, the lowest visual rating, the lowest termite mortality, and the highest weight loss. For the treated samples, the results show that the samples for both wood species have a low resistance limit to termites at low temperatures and a short-drying time. The weight loss is also high for samples with high MC. The mortality rate of termites was also high in samples dried at high temperatures over a long period of time compared with samples dried at low temperatures for a short period of time. The visual rating results also showed the same trend as the weight loss results. The results for these three categories are identical for the no-choice, choice, and aboveground tests. The analysis demonstrates that the high material resistance of tropical wood species is mostly dependent on the temperature and length of time spent in the kiln
Evaluation of relationships between age-related changes in radial growth increments of stems and wood properties in Paulownia tomentosa trees grown in Fukushima, Japan: RADIAL GROWTH AND WOOD PROPERTIES IN PAULOWNIA TOMENTOSA
No full textThe information on the relationship between age-related changes in stem size and wood properties is essential for promoting plantation forestry and wood utilization using fast-growing tree species. In this study, age-related changes in radial growth increments of stems and wood properties were preliminarily examined using mixed-effects modeling in about 25-year-old Paulownia tomentosa trees planted in Fukushima, Japan. Gompertz model was well-fitted to age-related changes in stem diameter. The cambial ages showing the maximum current annual increment and mean annual increment estimated by the radial growth model were 5.4 and 7.3 yrs, respectively. Although radial growth decreased after certain cambial age, the mean annual increment value still showed more than 2 cm per yr until 25 yrs. Most anatomical characteristics increased from the pith and stabilized towards the cambium. On the other hand, physical and mechanical properties were stable from the pith towards the cambium: the fixed-effect parameter estimates in the selected y-intercept model were 0.29 g • cm–3 for air-dry density, 4.02 GPa for MOE, and 40.3 MPa for MOR, respectively. Thus, a large volume of xylem with low and stable values of physical and mechanical properties was produced for more than 20 yrs, suggesting that the rotation age of the plantation of this species can be determined from the viewpoints of wood quantity.In addition, the wood that forms at any cambial age can be used for utility applications
A comparative study on the bending strength of European spruce and Fujian Chinese fir
Full text linkThis paper compared the bending properties of European spruce (Picea abies (L.) H. Karsten) and Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) with differing densities and knot patterns to identify the most appropriate uses for the latter species. As expected, reduced density and increased knot size negatively affected the modulus of elasticity (MOE) and the modulus of rupture (MOR) of both species. The MOEs of European spruce were higher than those of Fujian Chinese fir and were higher in samples without knots. The effect of knots on bending strength was more pronounced in European spruce. The results indicated that Fujian Chinese fir and European spruce could be substituted for each other in some less-demanding structural applications, which helps improve the utilization of the latter species
Evaluation of withdrawal strength of self-tapping screw inserted into cross-laminated timber with different anatomical aspects: ABSTRACT
Full text linkThe use of cross-laminated timber (CLT) technology is witnessing an upsurge in Japan because of its satisfactory performance under seismic conditions. The withdrawal strength (fax) of a single self-tapping screw (STS) inserted into the CLT was observed using a withdrawal test. The experimental results showed that fax of the partially threaded STS was higher than that of the fully threaded STS when inserted perpendicular to the grain. The empirical model used to predict fax provided in the European standard for the design of timber structures was evaluated by comparing the predicted values with the experimental results, which showed that the empirical model was only suitable for predicting the withdrawal strength of specimens with STSs inserted perpendicular to the grain. Therefore, a new probabilistic model was proposed for specimens inserted with STSs inserted parallel to the grain. The failure modes with respect to the orthotropic anatomy of wood materials were observed.
Keywords: withdrawal strength, probabilistic model, failure mode
Mechanical Characteristics of Custom CLT Layups Laminated by Ponderosa Pine Harvested from Restoration Programs
No full textNational forest restoration programs aimed at effective mitigation of catastrophic wildfires and pest outbreaks in Western region of the United States yield a substantial amount of small diameter Ponderosa pine logs. Lumber produced from these logs is considered low-value due to lower mechanical properties compared to commercially harvested lumber. US Forest Service is seeking a value-added market for this material to offset the high costs of the forest restoration operations. Cross laminated timber (CLT) is considered one of the potential markets for the material. This study was a part of a larger project aimed at determination of feasibility of utilizing CLT fabricated from restoration harvested Ponderosa pine in a class of low-rise modular mass-timber construction. A CLT layup was designed based on the design requirements of a modular construction system determined in a parallel study. The mechanical characteristics of that layup were empirically verified through mechanical tests on prototype panels, three fabricated at a pilot-plant line at Oregon State University and two at an industrial manufacturing line. In all prototypes, grades No. 1, 2, 3 and ungraded laminations were assigned to all layers randomly. Standard ASTM D198 methods for long- and short-span flatwise bending tests were conducted to derive effective moment capacity, effective stiffness, and shear capacity of the layups. Optical measurement based on digital image correlation was used to derive effective shear rigidity of the specimens. There was no significant difference between the results obtained from the prototypes fabricated in the pilot-plant compared to those fabricated in an industrial setting. The outcomes of mechanical tests indicate that the prototype CLT panels exceeded the structural requirements. The effective moment capacity, stiffness, and shear rigidity were higher than the values estimated by the shear analogy method. Shear capacity was lower than predicted. It is concluded that the restoration program PP CLT layups can be custom designed to meet mechanical requirements for structural elements in certain class of modular buildings.  
Review on wood properties of indigenous tree species for pulp and paper production
Full text linkREVIEW ON WOOD PROPERTIES OF INDIGENOUS TREE SPECIES FOR PULP AND PAPER PRODUCTION
Abstract
This comparative review of the anatomical and chemical properties of indigenous tree species to determine their suitability for pulp and paper production, a sector crucial for industrial and economic development. Recognizing the critical gap in comprehensive documentation on the wood properties essential for paper production, this paper aims to serve as a benchmark for future research, guiding pulp and paper producers in selecting the most appropriate materials. It delves into the global and Indian scenarios, highlighting the pressing need for sustainable materials in the face of escalating greenhouse gas emissions from the building sector and the burgeoning demand for wood amidst dwindling supplies. By examining a variety of species, such as Albizia lebbeck, Albizia falcataria, Gmelina arborea, Melia dubia, Leucaena leucocephala, Acacia auriculiformis, and Dalbergia sissoo.The study not only explores their potential in pulp and paper production but also considers their ecological values, thereby emphasizing a holistic approach to resource utilization.
Keywords: Indigenous Tree Species, Wood Properties, Sustainable Utilization, Anatomical and Chemical Composition
 
