• Title, Summary, Keyword: physical & mechanical properties

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Changes of Physical and Mechanical Properties of Firefighter Protective Clothing After Radiant Heat Exposure (노출시간과 열강도에 따른 복사열 노출후의 소방보호복의 물리적 특성과 역학적 특성변화)

  • ;N.Pan;G.Sun
    • Journal of the Korean Society of Clothing and Textiles
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    • v.23 no.6
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    • pp.853-863
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    • 1999
  • the change of physical properties (thickness, weight, air permeability) and mechanical properties(abrasion resistance breaking load and displacement) of samples were determined after heat exposure by a RPP tester. The effect of exposure time and heat flux intensity on the changes and the relationship between physical properties and mechanical properties were investigated. FR treated cotton Kevlar/PBI and Nomex with different structureal characteristics were chosen for specimens. The changes of physical properties and mechanical properties were calculated based on their initial values before heat exposure. The longer exposure time and the high heat flux intensity the more changes of those properties. Heat flux intensity was more effective on the changes, The showed to be affected by an interplay of shrinkage and pyrolysis products loss. The changes of thickness and abrasion resistance showed to be higher for plain weave fabric and those of air permeabiliyt and breaking load and displacement for twill weave fabric. While FR treated cotton which have high RPP value experienced serious and detrimental changes after heat exposure Kevlar/PBI which has low RPP value showed no high changes. In conclusion it could be confirmed that when total performance of a protective clothing is estimated retention capability of physical and mechanical properties after heat exposure as well as RPP value must be considered.

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Physical and Mechanical Properties of Methyl Methacrylate-Impregnated Wood from Three Fast-Growing Tropical Tree Species

  • Hadi, Yusuf Sudo;Massijaya, Muh Yusram;Zaini, Lukmanul Hakim;Pari, Rohmah
    • Journal of the Korean Wood Science and Technology
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    • v.47 no.3
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    • pp.324-335
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    • 2019
  • Timber from plantation forests has inferior physical and mechanical properties compared to timber from natural forest because it is mostly from fast-growing tree species that are cut at a young age. Filling cell voids with methyl methacrylate (MMA) can improve the wood properties. The purpose of this study was to determine the physical and mechanical properties of MMA-impregnated wood from three fast-growing wood species, namely jabon (Anthocephalus cadamba (Roxb.) Miq.), mangium (Acacia mangium Willd) and pine (Pinus merkusii Jungh. & de Vriese). Wood samples were either immersed in MMA monomer or impregnated with it and then heated to induce the polymerization process. Jabon, which was the lowest density wood, had the highest polymer loading, followed by pine and mangium. The physical and mechanical properties of samples were affected by wood species and the presence of MMA, with higher-density wood having better properties than wood with a lower density. Physical and mechanical properties of MMA wood were enhanced compared to untreated wood. Furthermore, the impregnation process was better than immersion process resulting the physical and mechanical properties. Based on MOR values, the MMA woods were one strength class higher compared to untreated wood with regard to Strength Classification of Indonesian Wood.

Physical and Mechanical Properties of Breathable Waterproof Fabrics Manufactured by Wet and Dry Coating Processes (습건식 코팅법으로 제조한 투습방수직물의 물성 및 역학특성)

  • 정원영;안승국
    • Textile Science and Engineering
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    • v.38 no.9
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    • pp.460-467
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    • 2001
  • Recently, breathable waterproof fabrics have been sued in large quantities for sportswear with in population enjoying sports and leisure, so the studies on these materials have been steadily carried out. In this research, the breathable waterproof fabrics manufactured by a direct coating process were investigated to define the changes in physical and mechanical properties. Adhesion of coating to fabrics, tearing strength, tensile stress and strain ,and various mechanical properties at small deformation were analyzed for the coated and pre-coated fabrics. Significant differences were found in some fields. Especially, breathable waterproof fabrics became stiff and swear subjected to a complex mechanical load during the coating process, so those changes might affect comfort properties of clothed human body in movement. The conditions for high production efficiency with the most suitable qualities and comfort properties of breathable waterproof fabrics could be established. A criterion for selection of suitable materials by comparing and analyzing the physical properties of fabrics finished by different methods were established.

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Physical and Mechanical Properties of Particleboard made with Powdered Tannin Adhesives (분말상 탄닌수지로 제조한 PB의 물리.기계적 특성)

  • 강석구;이화형
    • Journal of the Korea Furniture Society
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    • v.14 no.2
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    • pp.1-12
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    • 2003
  • This study was carried out to determine the mechanical and physical properties of particle boards glued with condensed tannin (Wattle Tannin) powder that was single-molecule phenolic compounds like powdered phenolic resin. Our findings are; 1) It is necessary to spray water on the chip surfaces for effective application of powdered -form tannin resin. It shows that the best and optimum mat moisture increase is 14% of water spray on the surface of chips for developing PB properties. 2) In general, for both liquid and powdered tannin adhesives, their physical and mechanical properties has been proportional to the increase of resin level. But, the most efficient addition ratio is 16% of resin on dry basis. Specially, it is found that the resin level influences on the amount of free formaldehyde emission. The higher the resin level is, the lower the emission is. These phenomena seem to result from the increase of hexamine or formaline in the adhesives used as a hardener, that reduce the free-formaldehyde amount by reaction of tannin of poly-molecule and water. 3) The optimum condition for manufacturing PBs is the condition of hexamine of 5% and formaline of 6% in mechanical and physical properties. Hexamine is superior to formaline in mechanical and physical properties along with the control of the free formaldehyde emission amount. The result of NaOH's addition is insignificant in all experiments of both mechanical and physical properties.

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Prediction of the mechanical properties of granites under tension using DM techniques

  • Martins, Francisco F.;Vasconcelos, Graca;Miranda, Tiago
    • Geomechanics and Engineering
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    • v.15 no.1
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    • pp.631-643
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    • 2018
  • The estimation of the strength and other mechanical parameters characterizing the tensile behavior of granites can play an important role in civil engineering tasks such as design, construction, rehabilitation and repair of existing structures. The purpose of this paper is to apply data mining techniques, such as multiple regression (MR), artificial neural networks (ANN) and support vector machines (SVM) to estimate the mechanical properties of granites. In a first phase, the mechanical parameters defining the complete tensile behavior are estimated based on the tensile strength. In a second phase, the estimation of the mechanical properties is carried out from different combination of the physical properties (ultrasonic pulse velocity, porosity and density). It was observed that the estimation of the mechanical properties can be optimized by combining different physical properties. Besides, it was seen that artificial neural networks and support vector machines performed better than multiple regression model.

Evaluation of geomechanical and geochemical properties in weathered metamorphic rocks in tropical environment: a case study from Samanalawewa hydropower project, Sri Lanka

  • Udagedara, Dashan T.;Oguchi, Chiaki T.;Gunatilake, Jagath K.
    • Geosciences Journal
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    • v.21 no.3
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    • pp.441-452
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    • 2017
  • The effect of weathering on changes of physical and mechanical properties of rocks is a prime concern in the perspectives of geology and engineering. These properties have been studied mostly on weathered igneous and sedimentary rocks under humid climates. Studies on weathering of metamorphic rocks, especially under a tropical climate, are rare. This study evaluates change of physical, mechanical, chemical, and mineralogical properties of metamorphic rocks that weather under tropical climatic conditions. Samanalawewa hydropower project area was selected for this study, because rapid weathering of a metamorphic rock (sillimanite garnet gneiss) was observed in the project site. Fresh rocks that are subjected to weathering have reached to completely weathered condition in a time span of less than 25 years in this area. Visually assessed weathering grades were physically and mechanically evaluated using bulk density, equotip hardness, porosity, specific gravity, point load strength, and slake durability tests. Mechanical properties, especially point load strength, change rapidly at the onset of weathering, while chemical properties show significant changes at later stages of weathering. Mineralogical changes such as appearance of secondary minerals are at the latter part of weathering. Physical properties gradually change during weathering. The observed changes in physical, mechanical and chemical properties indicate that their variations during weathering are independent of lithology and climatic conditions.

Physical and Mechanical Properties of Wood Fiber-Polypropylene Fiber Composite Panel

  • Kim, Jee-Woong;Eom, Young-Geun
    • Journal of the Korean Wood Science and Technology
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    • v.29 no.3
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    • pp.36-46
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    • 2001
  • This study was to find a way of reusing wood and plastic wastes, which considered as a troublesome problem to be solved in this age of mass production and consumption, in manufacturing wood fiber-polypropylene fiber composite panel. And the feasibility of this composite panel as a substitute for existing headliner base panel of automobile was also discussed, especially based on physical and mechanical performance. Nonwoven web composite panels were made from wood fiber and polypropylene fiber formulations of 50 : 50, 60 : 40, and 70 : 30, based on oven-dry weight, with densities of 0.4, 0.5, 0.6, and 0.7 g/$cm^3$. At the same density levels, control fiberboards were also manufactured for performance comparison with the composite panels. Their physical and mechanical properties were tested according to ASTM D 1037-93. To elucidate thickness swelling mechanism of composite panel through the observation of morphological change of internal structures, the specimens before and after thickness swelling test by 24-hour immersion in water were used in scanning electron microscopy. Test results in this study showed that nonwoven web composite panel from wood fibers and polypropylene fibers had superior physical and mechanical properties to control fiberboard. In the physical properties of composite panel, dimensional stability improved as the content of polypropylene fiber increased, and the formulation of wood fiber and polypropylene fiber was considered to be a significant factor in the physical properties. Water absorption decreased but thickness swelling slightly increased with the increase of panel density. In the mechanical properties of composite panel, the bending modulus of rupture (MOR) and modulus of elasticity (MOE) appeared to improve with the increase of panel density under all the tested conditions of dry, heated, and wet. The formulation of wood fiber and polypropylene fiber was considered not to be a significant factor in the mechanical properties. All the bending MOR values under the dry, heated, and wet conditions met the requirements in the existing headliner base panel of resin felt.

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A Study on the Physical and Mechanical Properties of Some Major Northern Soft woods and Hardwoods (북양산(北洋産) 주요(主要) 침(針), 활엽수재(闊葉樹材)의 재질(材質)에 관(關)한 연구(硏究))

  • Park, Jong-Su;Kim, Su-Chang
    • Journal of Forest and Environmental Science
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    • v.9 no.1
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    • pp.10-18
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    • 1993
  • The study was carried out to investigate the physical (Density, Percentage of latewood, Percentage of pore zone, Mean annual ring width) and mechanical (Compressive strength parallel to the grain, Compression perpendicular to the grain, Shearing strength) properties of some major northern softwoods and hardwoods. The physical and mechanical properties of each species are summerized as Table 2 and the relationship between physical and mechanical factors are discussed. The results of this study were as follows: Density and percentage of latewood are closely related to physical and mechanical properties, but percentage of pore zone and mean annual ring width are remotely related to physical and mechanical properties.

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Effect of Air-jet Texturing Processing Parameters on Physical Properties of New Synthetic Polyester Filament (에어젯트 텍스쳐 제조공정조건이 신합섬용 폴리에스테르사의 물성에 미치는 영향)

  • 김승진;한원희
    • Textile Science and Engineering
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    • v.32 no.7
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    • pp.679-689
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    • 1995
  • The physical properties of air-jet texturing yarn with various processing conditions are investigated in this paper. Physical and mechanical properties of air-jet textured yams manufactured with Hemma Jet T311 type are measured with various processing conditions such as overfeed, air pressure and dry/wet effect. Polyester filaments used are 75d/36f semi dull, which is used for core, and 75d/72f semi dull, which is used for effect in the yarn, respectively. The other polyester filaments used are 40d/24f, which is high shrinkable yam and 50d/24f, which is cation fibre, both are used for core in the yam. Physical properties measured are yarn linear density, yarn stability(instability and decay) by the stress-strain dlayim, loop structure by SEM. Mechanical properties measured are tenacity, modulus, ym, compression, and bending property. These physical and mechanical properties are analysed and discussed with various processing parameters such as overfeed, air pressure and dry/wet condition.

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Physical and Mechanical Properties of Sludge-Particle Board Manufactured by Composition Types and Composition Ratios from Mixed or Layered Paper Sludge and Wood Particle (구성형태(構成形態)와 구성비율별(構成比率別)로 제조(製造)한 슬러지-파티클보드의 물리적(物理的) 및 기계적(機械的) 성질(性質))

  • Lee, Phill-Woo;Yoon, Hyoung-Un
    • Journal of the Korean Wood Science and Technology
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    • v.24 no.1
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    • pp.17-26
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    • 1996
  • This research was accomplished to evaluate possibility of using paper sludge for the raw materials of wood based panel products. The experimental panels were manufactured by four mixed ratios, the proportion of paper sludge to wood particle: 20:80, 30:70, 40:60, 50:50% (oven dry weight basis) and by three composition types, sludge-particle mixed board, three layered sludge-particle board and three layered particle board. They were tested mechanical (bending strength and internal bond) and physical properties (water absorption, thickness swelling and linear expansion). From the results they were shown that bending strength of mixed and three layered sludge-particle board were decreased with increasing of composition ratios of sludge. And the mechanical and physical properties of the boards of three layered composition types have superior to those of mixed composition type. Although composition ratios of sludge increased, the internal bond strength and dimensional stability of sludge-particle board not decreased quantitatively. We concluded that the mechanical and physical properties of three layered sludge-particle board were similar w those of three layered particle-board (control) made by our laboratory design. Therefore, it was recognized that paper sludge can be used as potential raw material in particle-board manufacturing industry.

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