• Title/Summary/Keyword: bending MOR

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Manufacturing Characteristics of Boards Recycling Waste Wood Particle (폐목재파티클을 이용한 재생보드의 제조특성)

  • Kim, Wae-Jung;Suh, Jin-Suk;Han, Tae-Hyung;Park, Jong-Young
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.1
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    • pp.120-127
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    • 2006
  • The hammer-milled characteristics of waste wood materials such as lumber, plywood, particleboard(PB), MDF and railroad tic were investigated in this study. The physical and mechanical properties of recycled boards according to types of recycled particle and the mixing ratios were also studied. The hammer-milled, waste wood materials had the dimensional distributions suitable for the core layer panicle. Bending strengths of recycled boards (one layer) were shown in order of plywood, PB(laboratory-fabricated with particles used in the PB factory), lumber, tego film-overlaid plywood, MDF, waste railroad tie, PB(factory-made) and LPL-overlaid PB. Cured resin and creosote containing waste wood contributed to dimensional stability of reconstituted boards. Considering the mixing effects between lumber and plywood with recycled PB particle, lumber particle was contributive to bending strength, MOE and internal bond(IB) strength, whereas plywood particle was contributive to dimensional stability. The bending and IB strength of 3 layer boards composing only recycled waste wood particles in core layer of board were in order of lumber, plywood, PB and MDF. On the other hand, the thickness swelling was in order of PB, lumber, plywood and MDF. Bending strength of the 3 layer boards mixed with recycled PB-particle in the core layer had a decreasing tendency, as the mixing ratios of recycled PB-particles increased. The dimensional stability of 3 layer recycled board was improved as the mixing ratio of recycled PB-particle increased same as in one layer. Formaldehyde emission of boards fabricated with recycled PB-particles in the core layer of the PB was in the range of E2 grade (below 5.0mg/l).

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Effect of Hot-Pressing Time and Temperature on Properties of Bamboo Zephyr Boards (대나무 Zephyr 보드의 제조에 있어서 열압시간과 열압온도가 보드성능에 미치는 영향)

  • Jung, Ki-Ho;Kim, Yu-Jung;Roh, Jeang-Kwan;Park, Sang-Jin
    • Journal of the Korean Wood Science and Technology
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    • v.31 no.2
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    • pp.77-83
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    • 2003
  • In this research, in order to investigate the effect of hot-pressing condition, properties of bamboo zephyr boards (target density 0.7 g/cm3, 400×400×12 mm) produced by different hot-pressing time and temperature were compared through Korean Standard(KS) F 3104 and F 3113, and the results were summarized as follows: All of the boards had comparatively high values in bending properties (MOR, MOE) irrespective of hot-pressing condition, and the boards hot-pressed by 160℃ and 12 min showed the highest strength in parallel direction of board-surface to span. Internal bond (IB) strength of the boards generally increased with the increase of hot pressing temperature. Boards produced by hot pressing temperature and time of 160℃ and 12 min and 180℃ and 10 min exhibited relatively higher wet-bending strength. Thickness swelling (TS) of all the boards showed good dimensional stability of 6% or less.

Effect of Bonding on Bending and Shear Strength of COMPLY Composed of Fire Retardant Treated Particleboard (내화처리(耐火處理) 파티클보오드의 COMPLY접착(接着)이 휨강도(強度)와 전단강도(剪斷強度)에 미치는 영향(影響))

  • Lee, Phil Woo;Kwon, Jin Heon
    • Journal of Korean Society of Forest Science
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    • v.64 no.1
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    • pp.26-32
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    • 1984
  • This research was conducted to examine the effect of bonding on the bending and shear strength of COMPLY-board when used with meranti face veneer and fire retardant treated particle-board core. For ammonium sulfate, modulus of rupture (MOR) of COMPLY-board increased with increasing chemical concentration up to 10 percent and then decreased after that concentration. However, Minalith showed reverse effect to the result for ammonium sulfate. Modulus of elasticity (MOE) of COMPLY-hoard decreased with increasing chemical concentration and its differences were not significant between concentration. Shear strength was shown better when treated with ammonium sulfate than with Minalith. Wood failure of COMPLY increased with increasing chemical concentration up to 15 percent and then decreased after that concentration. The products of parallel and cross veneer laminated were better than those of COMPLY composed of fire retardant treated particle-board core. Non-treated particle-board was the least in strength. MOE of fire retardant treated COMPLY increased by 136 percent and its MOE by 170 percent as compared with non treated particle-board.

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Bending Creep of Glulam and Bolted Glulam under Changing Relative Humidity

  • PARK, Junchul;SONG, Yojin;HONG, Soonil
    • Journal of the Korean Wood Science and Technology
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    • v.48 no.5
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    • pp.676-684
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    • 2020
  • This study was carried out in order to evaluate the bending creep deflection of glulams and bolted glulams beam-to-beam connection with steel-gusset plates and bolts under changing relative humidity. The two types of glulam beams (130 mm in width, 175 mm in thickness, and 3000 mm in length) used in this study were made from domestic larch and composed of seven layers. The gussets were made of 8-mm-thick steel plates. Creep testing was conducted under constant loads in an uncontrolled environment. The test was carried out in a room that was well ventilated through a window. The creep test specimens were loaded for 33,000 hours. A bending creep test for the glulams was conducted through four-point loading. The applied stresses were 20% and 30% of the MOR in the static bending test for the glulam and bolted glulam, respectively. After 33,000 hours, the creep deflection of the glulam at a 20% stress level increased by 39% to 99%, while the creep deflection of the glulam at a 30% stress level increased by 27% to 67%, as compared with instantaneous elastic deflection. The relative creep increased during autumn and winter, and recovered during spring and summer. The relative creep of the bolted glulams was changed abruptly by loading up to 5,000 hours, but stabilized after 5,000 hours, and then gradually increased until 33,000 hours. The relative creep of the bolted glulam increased 2.11 times on average after 33,000 hours.

Effect of Annual Ring Angles on Static Bending Strength Performances of Cross-Laminated Woods Made with Spruce (연륜경사각이 가문비나무 직교형적층재의 정적 휨 강도성능에 미치는 영향)

  • Sung, Eun-Jong;Kwon, Chang-Bae;Ryu, Hyun-Soo;Byeon, Hee-Seop;Park, Han-Min
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.3
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    • pp.290-300
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    • 2014
  • In this study, cross-laminated woods were made with spruce wood and the effects of annual ring angles of perpendicular direction laminae on static bending strength performance were investigated. Static bending strength performances of parallel laminated woods with all layers composed of laminae perpendicular to the grain ($P_{\bot}$ type) were in the order of $90^{\circ}$ > $0^{\circ}$ > $45^{\circ}$. The MOE and MOR for the $45^{\circ}$ annual ring angle were 0.0989 GPa and 3.25 MPa, and it showed the lowest values. By placing longitudinal-direction laminae in the core of $P_{\bot}$ type, the strength performances were markedly improved. In the case of cross-laminated woods with perpendicular-direction laminae in the faces ($C_{\bot}$ type), the bending strength performances were in the order of $90^{\circ}$ > $0^{\circ}$ > $45^{\circ}$, but the differences among annual ring angles were less than those of the parallel-laminated woods. In the case of cross-laminated woods with perpendicular-direction laminae in the core ($C_{\parallel}$ type), the bending strength performances were in the order of $45^{\circ}$ > $90^{\circ}$ > $0^{\circ}$ unlike $P_{\bot}$ type and $C_{\bot}$ type. The MOE and MOR for the $45^{\circ}$ annual ring angle were 12.0 GPa and 55.8 MPa, and it showed the highest values.

Studies on Manufacturing Wood Particle-Polypropylene Fiber Composite Board

  • Lee, Chan-Ho;Eom, Young-Geun
    • Journal of the Korean Wood Science and Technology
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    • v.29 no.3
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    • pp.47-58
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    • 2001
  • For finding both ways of recycling the wood and plastic wastes and solving the problem of free formaldehyde gas emission through manufacturing wood particle-polypropylene fiber composite board without addition of formaldehyde-based thermosetting resin adhesive, control particleboards and nonwoven web composite boards from wood particle and polypropylene fiber formulation of 50 : 50, 60 : 40, and 70 : 30 were manufactured at density levels of 0.5, 0.6, 0.7, and 0.8 g/$cm^3$, and were tested both in the physical and mechanical properties according to ASTM D 1037-93. In the physical properties, control particleboard had significantly higher moisture content than composite board. In composite board, moisture content decreased with the increase of target density only in the board with higher content of polypropylene fiber and also appeared to increase with the increase of wood particle content at a given target density. Control particleboard showed significantly greater water absorption than composite board and its water absorption decreased with the increase of target density. In composite board, water absorption decreased with the increase of target density at a given formulation but increased with the increase of wood particle content at a given target density. After 2 and 24 hours immersion, control particleboard was significantly higher in thickness swelling than composite board and its thickness swelling increased with the increase of target density. In composite board, thickness swelling did not vary significantly with the target density at a given formulation but its thickness swelling increased as wood particle content increased at a given target density. Static bending MOR and MOE under dry and wet conditions increased with the increase of target density at a given formulation of wood particle and polypropylene fiber. Especially, the MOR and MOE under wet condition were considerably larger in composite board than in control particleboard. In general, composite board showed superior bending strength properties to control particleboard, And the composite board made from wood particle and polypropylene fiber formulation of 50 : 50 at target density of 0.8 g/$cm^3$ exhibited the greatest bending strength properties. Though problems in uniform mixing and strong binding of wood particle with polypropylene fiber are unavoidable due to their extremely different shape and polarity, wood particle-polypropylene fiber composite boards with higher performance, as a potential substitute for the commercial particleboards, could be made just by controlling processing variables.

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A study on the Bending Property of Structural Size Skin-Timber (대단면 스킨팀버의 휨 성질에 관한 연구)

  • Kim, Gwang-Chul
    • Journal of the Korean Wood Science and Technology
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    • v.40 no.1
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    • pp.26-37
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    • 2012
  • Recently, the demand and supply on the Hanok have been increased. However, Hanok should be requested larger section of structural members because of excessive roof weight. So, structural skin-timber was manufactured to get a lightweight structural member. The structural skin-timber has exterior shape with larger section but a great volume of wood be removed. The reduced strength of structural skin-timber can be supplemented by hybridizaion of structural member. Japanese larch and Domestic pine were used to manufacture the structural skin-timber. Structural skin-timbers of rectangular shape and cylinder shape were manufactured and tested to evaluate the bending properties. The intended strength property could not be obtained because member had been suffered severe damage by precision deficiency of manufacturing machine. However, if precision of manufacturing machine would be improved and additional hybridizaion of structural skin-timber would be done, lightweight structural member will be able to be manufactured. Structural skin-timber did not showed statistical significancy between two species, so it is possible to use pine mixed with larch. Only MOR of larch showed statistical significancy between rectangular shape and cylinder shape, so it is necessary to use of those as separate things. However, the rest of skin-timber can be judged mixed using because of non statistical significancy. The objective of this study was the development of lightweight larger structural member with relatively strength. If hybrid member of skin-timber could be developed with wood-ceramics, lightweight steel and more, it can be possible to be used as a building material of Hanok, interior material, post & beam construction material and more.

Bending and Bonding Strength Performances of Larix Block-glued Glulam (낙엽송 블록접착집성재의 접착 및 휨 강도 성능)

  • Lee, In-Hwan;Hong, Soon-Il
    • Journal of the Korean Wood Science and Technology
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    • v.44 no.3
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    • pp.315-322
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    • 2016
  • Block-glued glulam is a structural material that can be used as a construction member of a large-section wooden building, which is produced by edgewise bonding of two or more glulam beam elements. The edgewise bonding performance of the block-glued glulam was examined through delamination test and block shear strength test. According to the test results, the block-glued glulam that was manufactured with 1.5 MPa of compressive pressure after applying $500g/m^2$ of Resorcinol adhesive showed the best edgewise bonding performance. The block-glued glulam produced in a good edgewise bonding condition was compared with a control glulam with the same section modulus for bending strength performance. The modulus of elasticity (MOE) in bending was similar to that of the control glulam. The modulus of rupture (MOR) of the block-glued glulam was higher by 27% than that of the control glulam. No interfacial failure or cohesive failure were observed in the edgewise bonding layer.

The Mechanical Properties of Heat-Compressed Radiata Pine (Pinus radiata D.Don) - Effect of Press Temperature & Time - (열압밀화 라디에타 소나무재의 역학적 특성)

  • Hwang, Sung-Wook;Lee, Won-Hee
    • Journal of the Korean Wood Science and Technology
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    • v.39 no.4
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    • pp.303-310
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    • 2011
  • The mechanical properties of heat-compressed Radiata pine (Pinus radiata D.Don) by compression temperature and time were investigated. The compressive strength and bending strength of heat-compressed wood increased with increasing compression temperature and time. But the compressive strength and bending strength decreased with press temperature $220^{\circ}C$. It was considered due to thermal degradation during high temperature conditions. The surface hardness of heat-compressed wood increased with increasing compression temperature. However, the effect of compression time was negligible. The nail holding power was not affected by compression temperature and time.

Study on the Evaluation of Performance for Pitch Pine Round Timbers as Safety Barrier Beam Members

  • Lim, Jin-Ah;Yeo, Hwan-Myeong;Lee, Jun-Jae
    • Journal of the Korean Wood Science and Technology
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    • v.39 no.5
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    • pp.390-397
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    • 2011
  • In this study, bending test was conducted as beam members in timber roadside safety barrier. The flexural properties of pitch pine round timber according to the diameters were evaluated. And then grading based on the growth characteristics applied to choosing the pitch pine round timbers which is met the criteria of guideline (Japan, 2008). MOR of round timber 160 mm is higher than other specimens from 100 mm to 140 mm. Because of lower juvenile wood ratio and higher density. The MOE of round timber is decreased according to the increment of diameter. Only 32% of the specimens has passed the limitations. Performance of pitch pine round timbers has confirmed to suitability roadside safety beam members according to the guideline (Japan, 2008).