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Effect of Climate and Wood Type on Elastic modulus of Heat-treated Wood and its Optimization by the Taguchi Method

BIORESOURCES 2024年第2期19卷 3138-3148页

作者： Gunes, Mehmet Ersin, Cagatay Altunok, Mustafa Cankiri Karatekin Univ Vocat Sch Design Dept Cankiri Turkiye Cankiri Karatekin Univ Elect & Automat Dept Vocat Sch Cankiri Turkiye Gazi Univ Fac Technol Wood Prod Ind Engn Ankara Turkiye

Wood, as the oldest building material, provides some of the basic needs of human beings, including shelter and protection. Wood is used in exterior cladding, carrier systems, joinery, ceiling -floor coverings, windows, doors, and furniture production. When wooden material is exposed to external weather conditions, due to its hygroscopic structure, its physical and mechanical properties deteriorate from exposure to moisture, temperature, and biological organisms. The bending modulus of elasticity of Scots pine (Pinus sylvestris L.), oak (Quercus petraea L.), and chestnut (Castanea sativa M.) wood that was tannin -impregnated and heat -treated at 160 degrees C, was investigated using Taguchi L9 (3 3 ). The sequence was optimized. After heat treatment, the carrier elements were subjected to artificial climate conditions. In the optimization of the data obtained, it was understood that the highest impact factor was the tree type. In contrast, the climate on the elastic modulus was the lowest impact factor. In Taguchi analysis, a mathematical prediction model was created using actual and predicted data using the S/N ratio's biggest -best equation. The R 2 of the model can be predicted with an accuracy rate of 98.6%.

关键词： Wooden Tannin impregnation modulus of elasticity in bending Taguchi method Optimization

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Bulk metallic glass cantilever beams: Outstanding at large-deflection deformation and their application in complaint mechanisms

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JOURNAL OF ALLOYS AND COMPOUNDS 2022年第0期906卷 164335-164335页

作者： Li, Diao-Feng Bai, Chun-Guang Zhang, Zhi-Qiang Chinese Acad Sci Shi Changxu Innovat Ctr Adv Mat Inst Met Res 72 Wenhua Rd Shenyang 110016 Peoples R China

Excellent combination of mechanical properties of bulk metallic glasses (BMGs) are a class of relatively young and promising candidate materials for compliant mechanisms (CMs), which are usually associated with the nonlinear large-deflection deformation. In this study, an effective design strategy was proposed to enhance the flexibility of BMG cantilever beam quantitatively, which by means of increasing the ratio of loading distance to beam thickness. Moreover, the accuracy of modulus of elasticity in bending, Eb, which measured by cantilever bending test was affected seriously by the support compliance of the fixed end, and the accurate Eb value of BMG beam can be attained after eliminating this influencing factor. The critical boundary condition of cantilever beams within the scope of small-deflection deformation was identified, which situates at non-dimensional deflection parameter, delta(y)/L, is 0.2. Correspondingly, the critical loading distance-to-thickness ratios, (L/t)(c), of cantilever beams within small-deflection deformation were derived for BMGs and conventional crystalline metals, which provide a criterion to predict the potential to achieving large-deflection deformation. It is noticed that by plotting the flexural stress-delta(y)/L relations for BMG and several conventional crystalline metals used in CMs, the unique advantages of BMG cantilever beam in the aspect of achieving large-deflection deformation and enduring higher flexural stress can be reflected more intuitively. These advantages of BMG cantilever beam are well suitable for CMs which designed to have a small footprint and requirement of large-deflection motions, such as in the fields of microelectromechanical systems (MEMS) and biomedicines. (c) 2022 Elsevier B.V. All rights reserved.

关键词： Metallic glasses Compliant mechanisms Cantilever beam Large deflection deformation modulus of elasticity in bending

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The effect of bending parameters on mechanical properties of bent oak wood

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EUROPEAN JOURNAL OF WOOD AND WOOD PRODUCTS 2018年第2期76卷 633-641页

作者： As, Nusret Hindman, Daniel Buyuksari, Umit Istanbul Univ Dept Wood Mech & Technol Fac Forestry Istanbul Turkey Virginia Tech Dept Sustainable Biomat Blacksburg VA USA Duzce Univ Dept Wood Mech & Technol Fac Forestry Duzce Turkey

The aim of this study was to investigate the mechanical properties of oak (Quercus petraea Liebl.) wood bent at different radii for locations of the tension and compression sides of wood using micro-mechanical test specimens. Two oak trees having straight stems with approximately 40 cm diameter were selected and two 4 m long logs were cut. Two different steaming pressures, two setting methods, and three different bending radii were examined. Additionally, a set of three controls was unbent. Mechanical properties including the modulus of rupture, modulus of elasticity in bending, tension and compression strength parallel to grain were measured from the convex and concave sides of all samples. bending strength, modulus of elasticity in bending, tension strength and compression strength properties on convex sides were greater than the corresponding properties on concave sides. All strength values significantly decreased with decreasing bending radius on both sides. On the convex side, strength and stiffness values of oak wood at 300 mm radius were greater when compared to control groups while the strength and stiffness values of oak wood were lower for 100 mm radius. The values for 200 mm radius, on the other hand, were not significantly different compared to the control group value. On the concave side, all of the bent groups had significantly lower strength and stiffness values than that of control group. The effect of bending radius and setting method on the strength and stiffness values of oak wood was statistically significant on both concave and convex sides. The effect of steam pressure was not significant.

关键词： Convexity Agrostis turning radius modulus of elasticity in bending Compressive strength OAK WOOD CONCAVE Tensile Strength Steam pressure modulus of rupture sidings set method Mechanical properties

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Environmentally-Friendly High-Density Polyethylene-Bonded Plywood Panels

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POLYMERS 2019年第7期11卷 1166-1166页

作者： Bekhta, Pavlo Sedliacik, Jan Ukrainian Natl Forestry Univ Dept Wood Based Composites Cellulose & Paper UA-79057 Lvov Ukraine Tech Univ Zvolen Dept Furniture & Wood Prod Zvolen 96053 Slovakia

Thermoplastic films exhibit good potential to be used as adhesives for the production of veneer-based composites. This work presents the first effort to develop and evaluate composites based on alder veneers and high-density polyethylene (HDPE) film. The effects of hot-pressing temperature (140, 160, and 180 degrees C), hot-pressing pressure (0.8, 1.2, and 1.6 MPa), hot-pressing time (1, 2, 3, and 5 min), and type of adhesives on the physical and mechanical properties of alder plywood panels were investigated. The effects of these variables on the core-layer temperature during the hot pressing of multiplywood panels using various adhesives were also studied. Three types of adhesives were used: urea-formaldehyde (UF), phenol-formaldehyde (PF), and HDPE film. UF and PF adhesives were used for the comparison. The findings of this work indicate that formaldehyde-free HDPE film adhesive gave values of mechanical properties of alder plywood panels that are comparable to those obtained with traditional UF and PF adhesives, even though the adhesive dosage and pressing pressure were lower than when UF and PF adhesives were used. The obtained bonding strength values of HDPE-bonded alder plywood panels ranged from 0.74 to 2.38 MPa and met the European Standard EN 314-2 for Class 1 plywood. The optimum conditions for the bonding of HDPE plywood were 160 degrees C, 0.8 MPa, and 3 min.

关键词： alder plywood high-density polyethylene film bending strength modulus of elasticity in bending shear strength thickness swelling water absorption

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USE OF bending TESTS AND VISUAL INSPECTION FOR MULTI-SCALE EXPERIMENTAL EVALUATION OF CHESTNUT TIMBER BEAMS STIFFNESS

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JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2016年第6期22卷 728-738页

作者： Sousa, Helder S. Branco, Jorge M. Lourenco, Paulo B. Univ Minho ISISE Dept Civil Engn P-4719 Braga Portugal

The assessment of existing timber structures requires the determination of the mechanical properties of the individual timber members, which is often obtained by visual grading combined with information of small clear wood specimens. The purpose of this work is to present the results obtained in a multi-scale experimental evaluation of 20 old chestnut (Castanea sativa Mill.) beams, aimed at defining the correlations between bending modulus of elasticity (MOE) in different scales of timber members in combination with visual grading. The results of bending tests, according to EN 408: 2010 (2010), were statistically analyzed to obtain correlations of bending MOE between and within different scales size. The results of visual inspection according to UNI 11119: 2004 (2004) regarding the presence and distribution of defects were considered for variation analysis of MOE, evidencing a significant variance between samples of different visual strength grades. Strong correlations within the same phase (coefficient of determination r(2) from 0.82 to 0.89) and moderate to high correlations for different phases (r(2) from 0.68 to 0.71) were found for bending MOE. Cumulative distribution functions for global MOE remained similar throughout the experimental phases. Moreover, percentage of segments attributed to a specific visual grade is given for each member and compared between scales.

关键词： chestnut beams modulus of elasticity in bending visual grading properties correlation bending stiffness variation

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Hydraulic efficiency compromises compression strength perpendicular to the grain in Norway spruce trunkwood

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TREES-STRUCTURE AND FUNCTION 2011年第2期25卷 289-299页

作者： Rosner, Sabine Karlsson, Bo Univ Nat Resources & Life Sci Dept Integrat Biol Inst Bot BOKU Vienna A-1180 Vienna Austria Forestry Res Inst Sweden Skogforsk S-26890 Svalov Sweden

The aim of this study was to investigate bending stiffness and compression strength perpendicular to the grain of Norway spruce (Picea abies (L.) Karst.) trunkwood with different anatomical and hydraulic properties. Hydraulically less safe mature sapwood had bigger hydraulic lumen diameters and higher specific hydraulic conductivities than hydraulically safer juvenile wood. bending stiffness (MOE) was higher, whereas radial compression strength lower in mature than in juvenile wood. A density-based tradeoff between MOE and hydraulic efficiency was apparent in mature wood only. Across cambial age, bending stiffness did not compromise hydraulic efficiency due to variation in latewood percent and because of the structural demands of the tree top (e.g. high flexibility). Radial compression strength compromised, however, hydraulic efficiency because it was extremely dependent on the characteristics of the "weakest" wood part, the highly conductive earlywood. An increase in conduit wall reinforcement of earlywood tracheids would be too costly for the tree. Increasing radial compression strength by modification of microfibril angles or ray cell number could result in a decrease of MOE, which would negatively affect the trunk's capability to support the crown. We propose that radial compression strength could be an easily assessable and highly predictive parameter for the resistance against implosion or vulnerability to cavitation across conifer species, which should be topic of further studies.

关键词： Compression strength perpendicular to the grain Conduit wall reinforcement Hydraulic efficiency modulus of elasticity in bending Norway spruce Structure-function relationships Vulnerability to cavitation Wood shrinkage

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Analysis of Selected Mechanical Properties of Construction Wood KVH and Parallam 2.0 E

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DRVNA INDUSTRIJA 2010年第1期61卷 15-26页

作者： Hrazsky, Jaroslav Kral, Pavel Mendel Univ Agr & Forestry Brno Fac Forestry & Wood Technol Brno 61300 Czech Republic

This paper summarizes the results of the analysis of selected physical and mechanical properties of construction wood KVH and composite material Parallam 2.0 E (below Parallam). The following properties were determined: bending strength, local modulus of elasticity in bending, modulus of elasticity in pure bending, modulus of elasticity in shear by the constant span method, compression strength along the grain, compression strength across the grain, tensile strength across the grain, density and moisture content. The determined values were compared to each other and the best material was evaluated. The analyzed materials showed not only different values of monitored properties but also different behavior in particular tests. The presented tables and diagrams show that Parallam demonstrates better strength properties in many cases than construction wood KVH but with respect to the high purchase price of Parallam a manifold higher difference was expected. Comparing both analyzed materials from the aspect of purchase costs, two-fold higher values of the majority of analyzed mechanical properties of Parallam as against the construction wood KVH are irrelevant. The price of construction wood KM is about EUR 250, and the price of Parallam is about EUR 1540 per m(3). Such a high price is the main cause of the minimum use of Parallam as against construction wood KVH.

关键词： construction materials construction wood KVH Parallam bending strength modulus of elasticity in bending tensile strength compression strength density moisture content

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THE INFLUENCE OF MOISTURE CONTENT ON THICKNESS SWELLING AND modulus OF elasticity IN ORIENTED STRAND BOARD bending

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WOOD RESEARCH 2009年第4期54卷 79-90页

作者： Boehm, Martin Czech Univ Life Sci Fac Forestry & Wood Sci Dept Wood Sci & Technol Prague 16521 Czech Republic

The main theme of this study was an analysis of the moisture content (MC), thickness swelling (TS) and its relationship to modulus of elasticity in bending (MOE), For this case samples from OSB/3 SUPERFINISH (Czech producer Kronospan) were used. All analyses were performed with EN 310 standard-sized specimens. The specimens were exposed to 15, 35, 50, 65, 85 and 100% relative humidity (RH) and 20 degrees C for absorption and desorption. Analysis results clearly show that MOE decreases with an increase of board moisture content. For an MC change from 5 to 22%, an average MOE loss of 44% in the parallel direction and 39% in the perpendicular direction was measured. This MOE loss corresponded to a 21% thickness swelling. Predictive equations expressing the MOE bending as a function of MC and TS were determined.

关键词： oriented strand boards (OSB) moisture content thickness swelling modulus of elasticity in bending

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Anisotropic characterization of particleboard by ultrasonic and static techniques

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RUSSIAN JOURNAL OF NONDESTRUCTIVE TESTING 2004年第9期40卷 605-610页

作者： Najafi, SK Marasht, AA Ebrahimi, C Tarbiat Modares Univ Nat Resources Fac Wood & Paper Sci & Technol Noor Iran

The anisotropic properties of particleboard (PB) are studied by ultrasonic and static techniques. Ultrasonic wave velocity and modulus of elasticity in bending (MOE) are determined at parallel and perpendicular to manufacturing direction and at the interval angles of 15degrees in clockwise and counter-clockwise directions. The experimental results are compared with the predicted values using empirical formulas such as the Hankinson and Jacoby equations. The results show that the ultrasonic wave velocity and MOE are the highest in the parallel direction in PB and the lowest values occurred in the perpendicular direction. The predicted ultrasonic wave velocity using the Hankinson and Jacoby equations are in close agreement with the measured value. The relationship among particles' angle, ultrasonic wave velocities, and MOE could be successfully presented by cubic and quadratic regression equations as well.

关键词： Cubic Parallel Lines Anisotropy Ultrasonic Waves modulus of elasticity in bending Anticlockwise Particle board Wave velocity Regression Equation

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