Composite wood products
Abbas Tamjidi; Mohammad Mehdi Faezipour; Kazem Doosthoseini; Ghanbar Ebrahimi; Habibollah Khademieslam
Abstract
In this study, the effects of mat moisture content and press temperature on physical and mechanical properties of three layered oriented strand boards were evaluated. Two levels of mat moisture content 7% and 10% and three levels of press temperature 180 ˚c , 200 ˚c and 220 ˚c were applied and 12 ...
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In this study, the effects of mat moisture content and press temperature on physical and mechanical properties of three layered oriented strand boards were evaluated. Two levels of mat moisture content 7% and 10% and three levels of press temperature 180 ˚c , 200 ˚c and 220 ˚c were applied and 12 mm in nominal thickness laboratory boards were made from mixture of three clones of ten-year-old hybrid poplar ( populous euramericana vernirubensis, p. e. I-214, P. e. 561/41) while the strands on the surface layers are aligned in the long direction of the board and the middle layer strands are cross aligned to the surface layers. In all treatments, board targeted density of 0/7 g/cm3 and press time of 8 min and phenol-formaldehyde resin (PF) content of 7% based on the oven dry weight of the strands were held constant. The mechanical and physical properties of the boards were measured as defined in relevant European standards EN 300 for OSB/1 and OSB/2. Overall results showed that all boards made from above mentioned conditions exceed the EN 300 standards for MOR, MOE, IB and TS24. The bending properties (MOR and MOE) of boards were significantly improved as the mat moisture content increased from 7 to 10%. The highest MOR was achieved at 10% mat moisture content and 220 ˚c press temperature and the highest MOE was achieved at 10% mat moisture content and 180 ˚c press temperature. The Modulus of Rupture (MOR) and Thickness swelling (TS24) were significantly improved as the press temperature increased from 180 ˚c to 220 ˚c. The lowest TS24 was achieved at 7% mat moisture content and 220 ˚c press temperature and the highest IB was achieved at 7% mat moisture content and 200 ˚c press temperature.
Mechanical conversion of wood and wooden fittings
Hamideh Abdolzadeh; Ghanbar Ebrahimi; Mohammad Layeghi
Abstract
In this study, structural performance of corner joint reinforced by fiber reinforced polymers (FRP) at the area of maximum tension stress was investigated under diagonal tension loading. Therefore 1 to 3 layers of unidirectional woven Glass, Carbon and Kevlar fibers were used and hand ...
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In this study, structural performance of corner joint reinforced by fiber reinforced polymers (FRP) at the area of maximum tension stress was investigated under diagonal tension loading. Therefore 1 to 3 layers of unidirectional woven Glass, Carbon and Kevlar fibers were used and hand lay-up was done by vinyl ester and epoxy resins. Results of load-displacement curve at yield point exhibited capability of the reinforcing layers in preventing joint opening to some extent under load. However, failure was observed at the joint due to picking fibers from wood surface or members fracture near the interface when loading increased. Since the reinforced zones of the joints by FRP show the maximum shear stress, consequently the separation of fibers from wood surfaces increased at these locations. The adhesion of FRP layers to joint surface was not appropriate due to difficult process of layering at right angle of joints followed by probable formation of air bubbles. The results of assessing FRPs reinforcing behaviour indicated that application of vinyl ester in comparison with epoxy as matrix exhibited better performance. In addition, glass and carbon fibers showed better performance than Kevlar fibers as reinforcing agents.
Sadegh Maleki; Mohammad Mehdei Faezipour; Ghanbar Ebrahimi; mohammad Layeghi
Abstract
The goal of this study was to investigate bending moment resistance of L-shaped screwed corner joints constructed of Plywood members. The thickness of plywood members was nominal 19mm that were compared with medium density fiberboard (MDF) and particleboard with 18mm thicknesses. Effects of thread screws ...
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The goal of this study was to investigate bending moment resistance of L-shaped screwed corner joints constructed of Plywood members. The thickness of plywood members was nominal 19mm that were compared with medium density fiberboard (MDF) and particleboard with 18mm thicknesses. Effects of thread screws (coarse and fine), screw diameter (3.5, 4 and 5 mm), and penetration depth (9, 15 and 28) on bending moment capacity of joints under diagonal tension were investigated. Test results indicated that a screw corner joint becomes stronger as either screw diameter or screw length is increased. Screw length was found to have a greater effect on moment capacity than the diameter. The highest bending moment resistance was observed for joints made with coarse screw which were 5 mm in diameter and 28 mm depth of penetration. The lowest bending moment resistance was observed in joints having fine screw, with 3.5 mm diameter and 9 mm penetrations. Results also showed that bending moment resistance with coarse thread drywall screws was higher than those of the fine thread drywall screws. Bending moment resistance of joints made of plywood was higher than those of joints made of medium density fiberboard (MDF) and particleboard.
Mechanical conversion of wood and wooden fittings
Mohssen Bahmani; Ghanbar Ebrahimi; Lyla Fathi
Abstract
Although doweled joints are vastly used in furniture frame, these are little. Information about its withdrawal strength. The intent of this study is both to obtain initial and primary information concerning the withdrawal strength of dowel pin and, as far as possible, to develop generalized expression ...
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Although doweled joints are vastly used in furniture frame, these are little. Information about its withdrawal strength. The intent of this study is both to obtain initial and primary information concerning the withdrawal strength of dowel pin and, as far as possible, to develop generalized expression to estimate its strength. In this study, the effect of dowel diameter from three levels of 6, 8 and 10 mm and two penetration depth levels of 9 and 12 mm on withdrawal strength has been investigated. The results show that the highest withdrawal strength belongs to dowel with diameter of 8 mm and penetration depth of 12mm. Based on statistical results the experimental model of has been obtained to predict withdrawal strength.
Physics and anatomy
Fardad Golbabaei; Ghanbar Ebrahimi; Abolfazl Kargarfard; Abbas Fakhryan roghani
Abstract
Oak (Quercus castaneafolia C.A. Mey) is one of the most important broadleaf species in the Caspian Forests of Iran. The wood of oak is highly appreciated in domestic wood industries especially furniture industry.
In this study which is a part of the extensive surveying project of the main wood engineering ...
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Oak (Quercus castaneafolia C.A. Mey) is one of the most important broadleaf species in the Caspian Forests of Iran. The wood of oak is highly appreciated in domestic wood industries especially furniture industry.
In this study which is a part of the extensive surveying project of the main wood engineering properties of Iranian woods, the natural variations of strength and related properties of two trees of about 70 years old from Shafarod Forests in Gilan province were investigated.
The properties were determined from tests on small clear specimens in the green and dry conditions following the ASTM Standard. The mechanical and physical properties studied include: stress at elastic limits, modulus of rupture, modulus of elasticity and modulus of elasticity in static bending; shear parallel to grain, maximum crushing strength, fiber stress at proportional limit and modulus of elasticity in compression parallel to grain; compression perpendicular to grain and specific gravity.
The results of statistical analysis showed that the mechanical strength of the wood was found to be affected by percentage of moisture content of wood specimens, height of sample tree and to some extend by geographical; cal direction.
Composite wood products
Mohammad ali Podinehpoor; Ghanbar Ebrahimi; Mehdi Tajvidi; Majid Chahar mahali; Ali akbar Ramtin
Abstract
In this investigation, the influences of two kinds of agricultural wastes (wheat and barely straws) mixed with Aspen particles were studied for use as insulation boards. Barely and wheat straws were chosen because of their availability. The manufacturing parameters were: a specific gravity of 0.2, 0.4 ...
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In this investigation, the influences of two kinds of agricultural wastes (wheat and barely straws) mixed with Aspen particles were studied for use as insulation boards. Barely and wheat straws were chosen because of their availability. The manufacturing parameters were: a specific gravity of 0.2, 0.4 and 0.6 gr/cm3, and residual agriculture contents (0/1 00, 10/90, 20/80 and 30/70 weight of residual agriculture/ wood particle) of 0, 10, 20 and 30wt%. A commercial urea-fonnaldehyde adhesive was used as composite binder. Sound absorption coefficients were measured at five frequencies (250, 500, 1000, 2000, and 4000 hertz).The results showed when frequencies increased, sound absorption increased until it reaches to 2000 hertz but in 4000 hertz, sound absorption decreased. Between manufacturing parameters, kind of straws didn't have significant influence on noise reduction coefficient. The best density for absorb waves under 1000 in hertz was 0.4 gr/cm3 with 30% of straws but for waves with frequency higher than 1000 in hertz the best density was 0.2 gr/cm3 with 30% of straws.
Physics and Mechanical Wood
Ghanbar Ebrahimi; Hossein Mahjob; Saeid Kazemi najafi
Abstract
Ultrasonic wave speed was measured in the longitudinal direction of Basswood on the top and bottom surfaces and center of lumbers during kiln drying in 3 Kiln load programs with final dry bulb of 80oC and different relative humidities. On the surfaces, wave speed decreased rapidly with MC declining from ...
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Ultrasonic wave speed was measured in the longitudinal direction of Basswood on the top and bottom surfaces and center of lumbers during kiln drying in 3 Kiln load programs with final dry bulb of 80oC and different relative humidities. On the surfaces, wave speed decreased rapidly with MC declining from green to FSP, but from FSP down to 7% moisture content wave speed did increased slowly. In the center of lumber, with decreasing MC from green to FSP, wave speed increased slowly, but by reducing MC to 7%, wave speed was rapidly increased. 5% MC, on the three surface of lumber, wave speed had no drastic difference. Results indicated that ultrasonic wave speed and MC of wood show a parabolic relationship. Further, results have shown that measuring ultrasonic wave speed is an appropriate method to control kiln drying program for hardwood lumber
Physics and Mechanical Wood
Habibalah Arabtabar; Abdolrahman Hosseinzadeh; Ali Rezanezhad; Ghanbar Ebrahimi
Abstract
The economical importance of railroads and their development in Iran have been caused those annually 500000 wood sleepers to be required, if sleepers are to be maintained in suitable condition. However, the wood resources are also limited, specially producing roadbeds with high classes. For conservation ...
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The economical importance of railroads and their development in Iran have been caused those annually 500000 wood sleepers to be required, if sleepers are to be maintained in suitable condition. However, the wood resources are also limited, specially producing roadbeds with high classes. For conservation of natural resources (Forests) we need to use logs with lower classes as well. The process of lamination can permits manufacturing sleepers from small logs. Therefore, the manufacturing of two half laminated ties (interface vertical or horizontal) were lower. As in Iranian beech is usually used for manufacturing sleepers, in this study it was also utilized to make dowel-laminated sleepers. The results of this study showed that, the processes of impregnation of dowel-laminated sleepers with preservative (Creosote) and depth of its penetration were better established than in usual sleepers. Laboratory test indicated that modulus of elasticity of two half laminated - vertical sleepers was the same as the usual sleepers but this resistance in two half laminated - horizontal sleepers was decreased. Finally after five years exposure under extensive service, tests no failures in dowel-laminated sleepers especially in vertical shapes were observed.
