Wood and Fiber Science (E-Journal)
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“A TASTE OF GRADUATE SCHOOL WITHOUT REALLY FULLY COMMITTING TO IT" THE UNDERGRADUATE EXPERIENTIAL LEARNING PROJECT AT OREGON STATE UNIVERSITY
No full textUndergraduate research experience has been proven to improve student learning and retention. Since 2018, Oregon State University Department of Wood Science and Engineering has offered Research and Extension Experiences for Undergraduates (REEU) through support from the United States Department of Agriculture (USDA) Education and Workforce Development program. Between 2018 and 2020, 31 undergraduate students conducted research and/or gained experience in Extension projects during a 12-wk summer internship. The goal of this work is to assess the success of mentor–mentee relationships and how the program benefits the mentees’ career. Data for this research consists of transcribed interviews of seven mentor–mentee pairs. Transcripts are qualitatively analyzed to capture insights regarding participants’ experiences in the program. Students who participated in the REEU program improved their research skills and soft skills such as adaptation, writing, and communication. As a result of their participation, students are more likely to attend graduate school
DIMENSIONAL STABILITY OF MODIFIED COMPOSITE PANELS
No full textDimensional stability of wood-based composites with changing moisture content remains an important challenge in the industry for many applications. Wood identification technologies have shown significant promise to improve dimensional stability. The main objective of this research project was to study the effectiveness of impregnation and heat treatments on wood composites when exposed to selected moisture environments. Moisture exposure conditions included one-sided water spray, one-sided liquid water contact, constant high RH, and cyclic exposure to high and low RH. Commercial moisture-resistant medium-density fiberboard (MDF) and birch plywood panels, as well as laboratory manufactured birch plywood panels, were modified by impregnation with phenol-formaldehyde (PF) resin, 1,3-dimethylol-4,5-dihydroxyethylenurea (DMDHEU) resin, or subjected to heat treatment at 205oC for 2 h to improve dimensional stability. All treatments improved moisture resistance. Plywood impregnated with PF or DMDHEU resin showed the lowest thickness swelling values, with maximum values not higher than 5% after 192 h of exposure. Heat-treated MDF and heat-treated plywood samples resulted in 11% and 6% thickness swell after water spray exposure, respectively. The heat-treated plywood resulted in lower linear expansion (LE) than untreated plywood, with an average reduction of 54%; whereas the heat-treated MDF material did not show improvement of LE relative to control MDF samples
DEVELOPMENT OF A MODIFIED STANDARD TERMITE TEST FOR MASS TIMBER PRODUCTS
Full text linkU.S. manufacturers are looking to expand the use of cross laminated timber panels (CLT) into the North American market, including states located in the southeast. However, there is no current assessment method for determining CLT vulnerability to the highly destructive native termites found throughout the U.S. The impact of these termites is particularly high in areas with suitable climate to their proliferation, such as the southeastern U.S. This study aimed to evaluate durability of CLT panels and to develop a laboratory assay to test susceptibility of this product to termites. Untreated CLT suffered mass loss of up to 43.8% in testing with an average visual rating of 7.2, indicating a moderate to severe attack with 10 to 30% of the cross-section of the product affected by termite intrusion. Recommendations were developed for inclusion in standardized testing protocols and will be presented to standards organizations as appropriate. The proposed method can also be applied to evaluate termite resistance of other mass lumber products such as parallel strand lumber, laminated veneer lumber, and Glulam
SWST STUDENT CHAPTERS: A VALUABLE MEANS OF BROADENING STUDENT PERSPECTIVES IN WOOD SCIENCE AND TECHNOLOGY
Full text linkI believe abstracts are not required for Editorials
EXPERIMENTAL MODAL ANALYSIS OF A PALM TREE LOG UNDER RADIAL VIBRATIONAL EXCITATION
Full text link Trees may be subject to rot-inducing agents that degrade the strength of the material making their trunk, and decrease the quality of their crop. Several techniques, both non-destructive and destructive, are available for assessing the extent of damage caused by rot in a tree trunk. The present work presents the results of a preliminary study conducted on a palm tree trunk for isolating a specific mode from its response to a vibrational excitation, namely the so-called “ovalling” mode. This latter is cross-sectional and in a circular cylinder manifests itself relatively locally, i.e. has little dependence on the lateral extension of the cylinder. An experimental modal analysis is made on a piece of a date palm tree trunk when set into vibration through a radial mechanical excitation, and the response is collected at points along a circumference on the trunk. The value of the resonance frequency of the ovalling mode was found to be somehow variable, probably resulting from some coupling phenomena between various modes of vibration due to the inhomogeneity, anisotropy and fibre-like structure of the trunk wood. As rot usually affects markedly the strength of the trunk wood, the frequency of the ovalling mode, which depends on the strength of the material, can be used for estimating the severity of rot attack in the trunk. A numerical simulation is also made to a cylinder as a simplified representation of a tree trunk
COMPARISON OF RESISTANCE AND BIODEGRADABILITY PROPERTIES OF WOOD-PLASTIC COMPOSITES FROM WOOD FLOUR/ PHB / HDPE / STARCH
Full text linkIn this study, mechanical and biodegradability properties of wood plastic composite were investigated. Beech (fagus orientalis) flour 40 wt% was used as a reinforcing base material, maleic anhydride as a coupling agents and nano clay to improve the properties were added. The polymer studied was polyhydroxybutyrate (PHB) and the other polymer was high-density polyethylene (HDPE) .Three groups of composites were produced, in two groups each of the polymers alone and in the third group a combination of two types of polymers was used as a matrix. Starch 8 wt% and 12wt% was used as a copolymer. The specimens were mixed using a twin-screw extruder and made with an injection molding machine and subjected to mechanical tests: tensile strength and module, bending strength and module, impact resistance tests and biodegradability tests. In mechanical properties, it was observed that wood plastic composite with PHB base material has lower resistance properties than composites containing HDPE. With the addition of starch, all resistance properties were significantly reduced compared to the control sample without starch in all three groups of composite samples. Starch could not play the role of copolymer well in any of the groups. The third group of samples presented better results in terms of resistance properties than the first group. Modulus and resistances increased compared to the first group. In the biodegradability test, the samples were buried at a height of 25 cm for three months. Weight loss was due to the destruction of wood flour, starch and natural polymers by soil microorganisms. The weight loss trend of the samples was increasing until the end of the second month and then decreasing
PERFORMANCE OF TIMBER BOARD MODELS FOR PREDICTION OF LOCAL BENDING STIFFNESS AND STRENGTH – WITH APPLICATION ON DOUGLAS FIR SAWN TIMBER
Full text linkEfficient utilization of structural timber requires accurate methods for machine strength grading. One of the most accurate methods presented this far is based on data of local fiber orientation on board surfaces, obtained from laser scanning. In this paper, two potential improvements of this method are examined. The first one consists of replacing a model based on simple integration over cross sections of boards for calculation of local bending stiffness by a 3D solid finite element (FE) model from which local bending stiffness is derived. The second improvement concerns replacement of a simple model for the fiber orientation in the interior of board by a more advanced one taking location of pith and growth direction of knots into account. Application of the alternative models on a sample of more than 200 Douglas fir boards, size 40 mm X 100 mm X 3000 mm, cut from large logs, show that each of the evaluated model improvements contributes to improved grading accuracy. When local bending stiffness is calculated utilizing the herein suggested FE model in combination with the improved model of fiber orientation in the interior of boards, a coefficient of determination to bending strength as high as 0.76 is obtained. For comparison, a coefficient of determination of 0.71 is obtain using the simpler original models
