• 제목/요약/키워드: Tension wood

검색결과 82건 처리시간 0.019초

합판 접착제의 첨가제로서 폴리에틸렌의 이용 (Use of Polyethylene as an Additive in Plywood Adhesive)

  • 오용성
    • Journal of the Korean Wood Science and Technology
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    • 제26권1호
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    • pp.14-18
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    • 1998
  • A low density polyethylene(LDPE) was examined as an additive in phenol-formaldehyde(PF) resin adhesive for bonding radiata pine plywood. The LDPE was supplied by the commercial manufacturer. The LDPE was compared to a commercial filler commonly used in structural plywood adhesives in the United States. The adhesive mixes were made by following the recommended procedure of Georgia-Pacific Resins Inc.. using plywood-type PF resin. A total of 48 three-ply plywoods. 6.3 mm nominal thickness and 30 by 30 em in size, were made at two press times (4 and 5 min). two press temperatures (150 and $160^{\circ}C$) and 30 minute assembly times for four adhesive mixing types. Evaluations of the LDPE addition were carried out by performance tension shear tests after two cycle boil aging tests on plywood per the U.S. Product Standard PS I-83. After accelerated-aging tests. plywoods were exhibited no delamination. The test results included tension shear strength and estimated wood failure values. The plywood test results support the use of polyethylene as an additive in plywood adhesives.

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충전제의 종류가 합판용 페놀수지 접착제에 미치는 효과 (Effect of Filler Types on Phenol-Formaldehyde Resin Adhesive for Plywood)

  • 오용성
    • Journal of the Korean Wood Science and Technology
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    • 제26권3호
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    • pp.48-52
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    • 1998
  • Residues such as walnut, pinenut and peanut shells were used as a filler in adhesive for bonding radiata pine plywood. The nutshell residues were prepared by simply drying to 8% moisture content and grinding the dry material using a laboratory Wiley mill with a $75{\mu}m$ (200 mesh) screen. The nutshells residues were compared to a commercial filler commonly used in adhesives by the structural plywood and laminated veneer lumber industry in the United States. The adhesive mixes were made by following the recommended procedure of Georgia-Pacific Resins, Inc., using phenol-formaldehyde resin. For each filler type, three-ply plywoods, 6 mm nominal thickness and 30 by 30 cm in size, were fabricated at two press times (4 and 5 min) and around 30 minute assembly time. Evaluations of the nutshell residues were carried out by tension shear tests after cyclic boil tests on plywood. The results of the performance test included tension shear strength and wood failure. All plywoods made with the nutshell fillers were comparable to those made with the control filler. These results indicate that nutshell residues would be suitable as filler for plywood adhesives.

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Essential Oil Penetration Depth in Prunus sargentii Rehder

  • Ahmed, Sheikh Ali;Hong, Seong-Du;Chun, Su-Kyoung
    • 한국가구학회지
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    • 제18권4호
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    • pp.307-311
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    • 2007
  • An experiment was conducted to know the essential oil penetration depth in radial and longitudinal direction of Prunus sargentii. Oil penetration depth was found greater than radial flow depth. Vessel conducted oil more than wood fiber. In radial direction, body ray parenchyma was found more permeable than marginal ray parenchyma and it was about 138% times higher. Furthermore penetration depth of oil in intercellular space was greater than ray parenchyma and it was about 250% higher than ray parenchymas. Initial flow speed was found high and then it gradually decreased.

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Shear Performance of Glass Fiber Reinforced Glulam Bolted Connection

  • Kim, Keon-ho;Hong, Soon-il
    • Journal of the Korean Wood Science and Technology
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    • 제43권5호
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    • pp.661-671
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    • 2015
  • To evaluate the shear performance of the textile glass fiber and the sheet glass fiber reinforced glulam bolted connections, a tension type shear test was conducted. The average yield shear strength of the bolted connection of reinforced glulam was increased by 12% ~ 31% compared to the non-reinforced glulam. It was confirmed that the shear performance of 5D end distance of the glass fiber reinforced glulam connection corresponds to that of 7D of the non-reinforced glulam connection proposed in building design requirements in various countries. Compared to the non-reinforced glulam, the average shear strength of textile glass fiber reinforced glulam was markedly increased. The non-reinforced glulam and the GFRP reinforced glulam underwent a momentary splitting fracture. However, the failure mode of textile glass fiber reinforced glulam showed a good ductility.

유한요소해석을 이용한 응력적층 바닥판의 구조성능평가 (Structural Performance Evaluation on Stress-Laminated Timber Bridge Deck Using Finite Element Analysis)

  • 신유경;엄창득;이상준
    • Journal of the Korean Wood Science and Technology
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    • 제42권1호
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    • pp.20-26
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    • 2014
  • 본 연구에서는 유한요소해석을 이용하여 응력적층 바닥판의 구조성능을 평가하였다. 바닥판의 구조성능은 처짐과 응력, 압체력의 변화로 평가할 수 있다. 하중 재하 후 바닥판의 처짐 형상을 확인한 결과 하나의 판처럼 거동하는 것을 확인하였다. 이는 압체력에 의해 각 부재 사이에 마찰력이 작용했기 때문이다. 또한 초기 압체력과 산출된 압체력을 비교한 결과 바닥판의 처짐과 함께 압체력이 감소했다. 이는 하중에 의해 바닥판의 변형이 발생하면서 작용하는 힘이 줄어듦에 따라 압체력이 감소한 것으로 판단된다. 그러나 재료의 소성 특성이 제대로 반영되지 않았기 때문에 잔류응력과 잔류변형이 고려되지 않았으므로 추후 이에 대한 연구가 필요하다.

증점제를 함유한 미분무수의 목재화재 소화효과 (Efficiency of Water Mist Suppression System Containing Viscosity Agent to Extinguish Wood Cribs Fire)

  • 김민형;신창섭
    • 한국안전학회지
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    • 제29권4호
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    • pp.78-84
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    • 2014
  • Viscosity agents were added to water to improve extinguishing performance of low pressure water mist suppression system on wood cribs fire, and a small scale wood cribs fire experiment was conducted to measure the extinguishing performance. CMC and agar were used for viscosity agent and as the amount of viscosity agent enlarges, it showed the increase of the viscosity of aqueous solution and the decrease of the fluidity. On wood cribs fire experiment, the extinguishing efficiency was improved with supplemental viscosity agent as it enhanced the adhesive time of aqueous solution on the wood, and therefore expanded the contact time of fire surface. The surface tension of aqueous solution was decreased with the addition of agar which to be assumed as an increase factor of extinguishing efficiency. By the extinguishing experimental result, the most effective extinguishing agent was CMC 0.6 wt.%, with the flame suppression time and the extinguishing time were reduced by 70s and 93s respectively at this concentration.

폴리모 모르터를 이용한 강화목재보의 개발 (Development of Reinforced Wood Beams Using Polymer Mortar)

  • 연규석
    • 한국농공학회지
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    • 제32권3호
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    • pp.79-86
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    • 1990
  • Based on limited number of tests on reinforced wood beams using polymer mortar in this study, following conclusions were drawn ; 1.Reinforcing compression side of wood beam using polymer mortar was effective in reducing deflection. 2.By increasing thickness of polymer mortar, effective beam stiffness was improved, but energy absorption was reduced. 3.Polymer mortar reinforcement improved compressive strength and reduced strain in compression side of the beam. Therefore, it was possible to change the failure mode from by compression in control beam to by tension in composite beams. 4.The composite beams that have more than 2cm of polymer mortar layer did not perform well because a strain redistribution and separation of meterials at interface were induced in moment span. 5.To maximize the load carrying capacity of composite beam, it is necessary to make polymer mortar and wood behave together without failing at interface. To do this, it is needed to use a polymer mortar which has high strength with such elastic modulus that is closer to elastic modulus of wood. otherwise, it is recommended to use shear connectors at interface to prevent separation of materials under ultimate load.

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산성(酸性) 조건하(條件下)에서 Sitka spruce의 기상(氣象) 열화(劣化) 가속(加速)에 관(關)한 연구(硏究) (Study of the Accelerated Weathering of Sitka spruce under Acidic Conditions)

  • 김재진;김규혁
    • Journal of the Korean Wood Science and Technology
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    • 제21권2호
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    • pp.9-14
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    • 1993
  • Weathering of wood in a region of acid rain was performed by the test which thin veneers of Sitka spruce were exposed to outdoor weathering for a total of 18 weeks, with a daily soaking for 30 minutes in acidified water in the pH range 2~5.6. The weathering measured by weight loss and loss in maximum failure load in tension was accelerated by the increase in the acidity of acidified water and in the period of outdoor exposure. It was also shown that the weathering was accelerated even with low acidic conditions in the case of long exposure period, although the weathering was rapidly accelerated with high acidic conditions. When compared the degree of weight loss with that of loss in failure load by weathering, the latter was much greater. From the results of this research, it could be concluded that at pH 4.0 or below of precipitation, the acceleration of weathering of exterior wood would become serious problems, which would be caused deterioration in performance of exterior wood.

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Longitudinal Penetration of Water through the Vessel and Wood Fiber in Castanea crenata

  • Ahmed, Sheikh Ali;Chun, Su-Kyoung
    • 한국가구학회지
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    • 제19권2호
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    • pp.111-115
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    • 2008
  • An experiment was conducted to know ultra-pure distilled water penetration depth through large vessel, small vessel, latewood fiber and earlywood fiber in longitudinal direction of Castanea crenata. In heartwood, latewood fiber transported water more than large and small vessel. While in sapwood, small vessel conduction depth was found the highest. Penetration depth of water after 15.0 seconds, no significant difference was observed among earlywood fiber, latewood fiber and earlywood vessel. Whilst in heartwood, no statistical difference was observed among earlywood fiber, latewood fiber and earlywood vessel. At the beginning, the speed of water penetration was high and then gradually decreased.

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Flow Behavior of Safranine Solution in Prunus sargentii Rehder

  • Hong, Seong-Du;Ahmed, Sheikh Ali;Chun, Su-Kyoung
    • 한국가구학회지
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    • 제18권4호
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    • pp.282-286
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    • 2007
  • An experiment was conducted to compare the 1% safranine solution flow depth in radial and longitudinal direction of Prunus sargentii. Longitudinal flow of safranine solution was found higher than radial flow. Body ray parenchyma was found more permeable than marginal ray parenchyma and it was about 1.3 times higher. Intercellular space conducted safranine solution more than ray parenchyma. Vessel was found to be the main avenue for liquid conduction in longitudinal direction. Different anatomical features of ray, vessel and fiber affected the penetration depth of safranine solution. Moreover initial penetration depth was found to be high and thereafter decreased gradually.

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