Wood and Fiber Science (E-Journal)
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Determination of Effective Coefficient of Chinese Fir (Cunninghamia Lanceolata) During Adsorption and Desorption Process
Full text linkEstablishing an accurate moisture transport model in wood is essential to analyze the hygroscopic behavior and estimate the stability of wood structures in the ambient environment. In this article, the effective diffusion coefficients (EDCs) of Chinese fir in radial and tangential directions during absorption and desorption processes were measured based on the differential model, and numerical simulations were performed to verify the rationality of measured results. The results show that 1) for adsorption process, the surface emission coefficient (SEC) and EDC of Chinese fir are all greater in the radial direction; 2) for desorption process, the SEC is higher in the radial directions, whereas the EDC in the tangential direction is higher than that in the radial direction when the MC is greater than 10%; 3) the SEC and EDC in the adsorption process are larger than those in the desorption process. Because there is a reasonable agreement between experimental and mumerical simulation results, the measured results could be used to predict the MC distribution of Chinese fir in the ambient environment
Assessing Southern Pine 2x4 and 2x6 Lumber Quality: Longitudinal and Transverse Vibration
Full text linkA primary goal of structural lumber grading is the identification of the strength-reducing characteristics that impact the modulus of rupture (MOR). Non-destructive evaluation technology can be used to identify material of greater stiffness. This study investigates the use of longitudinal and transverse vibration methods to evaluate the mechanical properties of 2x4 and 2x6 southern yellow pine lumber. A total of 1240 samples were conditioned to 12% equilibrium moisture content. All samples were first non-destructive tested using transverse vibration equipment (Metriguard E-computer) in edgewise and flatwise directions and three different longitudinal vibration devices (Fakopp Portable Lumber Grader, Director HM200, and Falcon A-grader) to obtain the vibration properties using transverse and longitudinal methods. The dynamic modulus of elasticity (MOE) of each sample was calculated based on the fundamental wave equation. Static bending was subsequently conducted according to ASTM 198 (2012), and the rate of loading followed ASTM D4761 (ASTM 2012). The results showed statistically significant correlations between static MOE and the dynamic MOE measured by non-destructive techniques. Weaker correlations were found between MOR and the dynamic MOE values. Likely this finding is because it is related to the ultimate strength of material, often associated with the existence of localized defects, such as a knot, on the lumber piece. This study indicates that non-destructive techniques can potentially be used to evaluate 2x4 and 2x6 stiffness and improvements can be done for a better evaluation of southern pine lumber
Effect of Supercritical Carbon Dioxide Treatment on Gas Permeability of Paulownia Fortunei Heartwood and Sapwood
Full text linkMany wood species are resistant to penetration of liquids. Impermeability can affect a variety of properties including the ability to deliver preservatives, adhesive bonding, and coating applications. Developing methods for altering this characteristic could help in utilization of impermeable species. One method for altering wood properties is through the use of supercritical carbon dioxide (SC-CO2) which can solubilize a wide range of organic compounds. In this report, we examined the ability of varying SC-CO2 conditions to improve the permeability of Paulownia fortunei. All of the processes tested improved gas permeability and most reduced the frequency of tyloses in the vessels. The results suggest that SC-CO2 could be used to modify the permeability of this species
EFFECT OF GROWTH RING WIDTH AND FIBER DIMENSIONS ON THE COMPRESSIVE STRENGTH OF SOME MEMBERS OF THE MORACEAE FAMILY
Full text linkInvestigations were carried out on the effect of growth ring width, fiber morphometrics, and wood type on the compressive strength of three members of the Moraceae family namely; Milicia excelsa, Treculia africana, and Antiaris toxicaria. Fiber diameter (D), Fiber length (L), fiber lumen diameter (l), cell wall thickness (c), derived fiber values, and growth ring width were measured and correlated with compressive strength. Results obtained revealed significant relationships: negative between growth ring width and compressive strength and positive between wood type and compression strength at p = 0.05 and p < 0.01 levels. A. Toxicaria had the highest compression strength which differed significantly (p = 0.05) when compared with T. africana and M. excelsa. On the other hand, T. africana was observed to have the smallest growth ring width and shorter fibers. It is evident from the results that species with narrower growth rings widths have higher compression strength, although some factors other than this, which may depend on the wood type, could equally influence the compression strength positively
Life-time improvement and the cutting forces in nitrogen-implanted drills during wood-based material machining
Full text linkThis study explored the effects of nitrogen (N) ion implantation of drills for wood-based materials. Modification of a tool’s surface is a common process of prolonging its lifetime. For the purpose of this study, ion implantation was used for modification of drills commonly used in the furniture industry. The rake face of high-speed steel drills was implanted with different doses of nitrogen ions. Durability tests were conducted with the use of a computerized numerical control woodworking machine used for drilling laminated particleboards. The cutting force and drilling torque were measured. The obtained results were presented as wear curves of the examined drill bits. Based on the results, tools implanted with nitrogen ions at different doses had a longer tool life
CUTTING TEST AS SOURCE OF FRACTURE TOUGHNESS AND SHEAR YIELD STRENGTH FOR AXIAL-PERPENDICULAR MODEL OF WOOD CUTTING
Full text linkThe objective of this study was to develop and design a model of calculation of fracture parameters for axial-perpendicular model of wood cutting. Two selected wood species of Central Europe provenance spruce (Picea abies L.) and beech (Fagus sylvatica L.) of two different levels of moisture content (w = 8% and 16%) were sawn. The measurements of energetic effects (cutting power and cutting force) while sawing wood were carried out on the laboratory stand which simulates conditions of circular saw blade cutting. Using the newly designed model, it is possible to determine fracture toughness and shear yield strength only on the basis of the cutting tests. Unknown parameters, which are then applied in the model, were set based on calculation of the forces acting on the workpiece and the tool. Using the measured cutting force and the feed force, other component of the resulting active force were calculated. The computation was based on Ernst-Merchant’s force decomposition diagram. Results confirmed the obvious influence of the anatomical structures and moisture content on the size of fracture parameters
OPTIMIZATION FOR THE LIQUEFACTION OF MOSO BAMBOO IN PHENOL USING RESPONSE SURFACE METHODOLOGY
Full text linkBamboo liquefaction is a key process during bamboo high-value utilization, such as bamboobased nano-carbon fiber manufacturing. Liquefaction parameters have direct effects on the performance of final products. The impact of mass ratio of phenol/bamboo (P/B) powder, temperature, and liquefaction time during moso bamboo liquefaction was studied. All these parameters were studied to perform experiments based on response surface methodology (RSM). Residue content was calculated to evaluate the efficiency of moso bamboo liquefaction. Mathematical models were developed to establish the relationship between the liquefaction parameters and residue content. The results showed that within certain limits the residue content decreased with the increase of P/B and temperature; however, a further increase of P/B and temperature caused the residue content to increase. In the selected range of liquefaction time in this study, the residue content decreased with the increase of liquefaction time. The optimized combination of liquefaction parameters was 4.5, 163°C, and 46 min for P/B, temperature, and liquefaction time, respectively. The optimized result of residue content from RSM was 7.41934E-008 (%), which meant the bamboo almost completely liquefied. Because of the reasonable error of experiment, the optimized result of residue content from the confirmation experiment was 0.06%.
METHOD FOR ASSESSING THE NATIONAL IMPLICATIONS OF ENVIRONMENTAL IMPACTS FROM TIMBER BUILDINGS—AN EXEMPLARY STUDY FOR RESIDENTIAL BUILDINGS IN GERMANY
Full text linkSince 2012, a set of new standards describing, among other aspects, the use of life cycle assessment (LCA) in the construction sector is available in Europe and provides a framework for consistently assessing the environmental performance of buildings. This article gives an overview of the actual state of art for evaluating the environmental properties of timber buildings in Europe and shows how these methods could be used as a basis for estimating the influence of a possible shift from conventional buildings to timber buildings on the national “Greenhouse Gas (GHG) budget,” whereby Germany serves as an example. Results from up-to-date LCA calculations of residential buildings for Germany are shown on a building level. Then a scaling from the building level to a national level is presented. On the national scale, the potential GHG impact of wood consumption in the building sector is modeled based on an insinuated future increase of the market share of timber buildings. The deviation of future emissions and removals due to the biogenic carbon storage effects for changing scenarios is presented. The approach shows how increasing timber construction (mass timber and timber frame) can contribute to achieving climate protection targets
MECHANICAL PROPERTY ASSESSMENT FOR ESTABLISHING DESIGN VALUES OF WESTERN JUNIPER
Full text linkWestern juniper (Juniperus occidentalis) is a conifer that is native to Oregon, California, Washington, Nevada, and Idaho. Juniper is highly decay resistant and, therefore, is a popular choice for fence posts and landscape timbers. Forest management practices over the past 100 yr have resulted in an immense population increase in western juniper stands, transforming the grasslands/sagebrush biome into juniper forests. Landowners have been encouraged to cut back western juniper to restore grassland habitat, but there is no major market associated with juniper lumber. This study assessed the mechanical properties of western juniper to develop its design values for inclusion in the National Design Specification. Small clear samples were prepared from juniper harvested from three locations in eastern Oregon, one location in northeast California, and one location in southwest Idaho according to ASTM D143 for compression, bending, and shear. Average strength values were calculated and compared with similar wood species. Most properties were similar to those of other species, but modulus of elasticity was significantly lower. Compressive properties of western juniper also differed, with compression parallel-to-grain being lower and compression perpendicular-to-grain being relatively higher. Differences between species might be attributed to cell wall structure and distribution of lignin in the cells. Design values for western juniper were calculated using the strength values to establish allowable properties for visually graded lumber