• Title/Summary/Keyword: aramid paper

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The Study on Application of Hybrid Insulation System for Thermally Upgraded Distribution pole Transformers (주상변압기 열적 특성 향상을 위한 복합절연 시스템 적용)

  • Lee, B.S.;Song, I.K.;Lee, J.B.;Kim, D.M.;Han, S.O.
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1896-1898
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    • 2002
  • In this paper, to developing thermally and mechanically upgraded ones, we dismounted pole transformers used in the fields for over 13 years and conducted aged oil analysis. Also, when the cellulose and aramid papers in test cell were aging with oil at $130^{\circ}C$ for 3000 hours, with the testing period cellulose paper deteriorated more rapidly than the others. For example dielectric strength and dissipation factor of papers deteriorated with aging time. For evaluation of thermal aging characteristics, a mineral oil-immersed transformer was constructed with hybrid insulation system comprised of aramid paper and cellulose insulation. A Hybrid system has economic advantages. Cellulose materials are confined to cooler regions of the transformer winding. And aramid papers are served to insulate contact parts of hot conductors.

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The FSI Analysis Evaluation of Strength for the Wind Turbine Rotor Blade Improved by the Aramid Fiber (아라미드섬유 보강 풍력발전기 로터 블레이드의 연성해석 강도평가)

  • Kim, Seok-Su;Kang, Ji-Woong;Kwon, Oh-Heon
    • Journal of Power System Engineering
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    • v.19 no.4
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    • pp.17-23
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    • 2015
  • Because of the energy resources shortage and global pollution, the wind power systems have been developed consistently. Among the components of the wind power system, the rotor blades are the most important component. Generally it is made of GFRP material. Recently, GFRP material has been replaced by CFRP composite material in the blade which has an aerodynamic profile and twisted tip. However the failures has occurred in the trailing edge of the blade by the severe wind loading. Thus, tougher material than CFRP material is needed as like the aramid fiber. In this study, we investigated the mechanical behaviors of the blade using aramid fiber composites about wind speed variation. One-way FSI (fluid-structure interaction)analysis for the wind rotor blade was conducted. The structural analyses using the surface pressure loading resulted from wind flow field analysis were carried out. The results and analysis procedure in this paper can be utilized for the best strength design of the blade with aramid fiber composites.

Improvement of Photo-stability for p-Aramid Fibers by SiO2/TiO2 Sol-Gel Method (SiO2/TiO2 sol-gel법을 이용한 p-아라미드 섬유의 내광성 증진)

  • Lee, Young-Il;Jung, Min-Hyuck;Lee, Mun-Cheul
    • Textile Coloration and Finishing
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    • v.25 no.3
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    • pp.172-180
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    • 2013
  • Aramid fibers are being used increasingly in a wide range of application due to low density, high specific strength, high modulus, and high thermal resistance. But owing to its special physical and chemical structures, it is sensitive to absorb the ultraviolet light which will degrade the fiber's useful mechanical properties and structure. In this paper, the sol-gel technique was used to improve the photo-stability of p-aramid fibers. $TiO_2$, modified $SiO_2$/$TiO_2$ sol were used as coating solutions. The influence of the such coatings on the photo-stability of p-aramid fiber was investigated by an accelerated photo-ageing method using xenon lamp. The photo-stability of p-aramid fiber showed obvious improvement after the modified silica binding coating. But the amorphous $TiO_2$ sol coatings showed a negative effect. After 144h light exposure, the modified silane binder-coated fibers showed less degradation in mechanical properties with the retained tensile strength greater than about 70% of the original value.

Review of the Composite Materials Application to the Solid Rocket Motor Cases (복합재료의 고체 로켓 모터 케이스 적용 리뷰)

  • Lee, Tae-Ho
    • Composites Research
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    • v.25 no.3
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    • pp.82-89
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    • 2012
  • This paper investigated the composite materials application examples and trends in the future to the solid rocket motor cases. The motor case must be stiff and tolerate at the high pressures, and light weight. In accordance to these kind of requirements, the composite materials showed the adaptable efficiency, and glass fibers, aramid, carbon fibers are applied to orderly. The comparison of the motor case efficiencies of the D6AC steel alloy, aramid, carbon fibers results in the carbon fibers best. Also the capacity of the payload will be increased more than 20% by using the high strength ones.

Thermal effects on the mechanical properties of cement mortars reinforced with aramid, glass, basalt and polypropylene fibers

  • Mazloom, Moosa;Mirzamohammadi, Sajjad
    • Advances in materials Research
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    • v.8 no.2
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    • pp.137-154
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    • 2019
  • In this study, thermal effects on the mechanical properties of cement mortars with some types of fibers is investigated. The replaced fibers were made of polypropylene (PP), aramid, glass and basalt. In other words, the main goal of this paper is to study the effects of different fibers on the mechanical properties of cement mortars after subjecting to normal and sub-elevated temperatures. The experimental tests used for investigating these effects were compressive, splitting tensile, and four-point bending tests at 20, 100 and $300^{\circ}C$, respectively. Moreover, the microstructures of the specimens in different temperatures were investigated using scanning electron microscope (SEM). Based on the experimental results, the negative effects of sub-elevated temperatures on four-point bending tests were much more than the others. Moreover, using the fibers with higher melting points could not improve the qualities of the samples in sub-elevated temperatures.

Improving the Photo-stability of p-aramid Fiber by TiO2 Nanosol (TiO2 sol-gel 합성에 의한 파라 아라미드 섬유의 내광성 증진 연구)

  • Park, Sung-Min;Kwon, Il-Jun;Sim, Ji-Hyun;Lee, Jae-Ho;Kim, Sam-Soo;Lee, Mun-Cheul;Choi, Jong-Seok
    • Textile Coloration and Finishing
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    • v.25 no.2
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    • pp.126-133
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    • 2013
  • Although para-aramid fibers poss higher mechanical properties, they show very low resistance to sunlight exposure. This paper studied on the effect of nano-sol coated $TiO_2$ to improve the photo-stability of p-aramid fibers. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio ($H_2O$/titanium iso-propoxide). All samples were characterized by XRD, TEM and UV-vis spectrometer. The mechanical properties of p-aramid fabrics by $TiO_2$ nano-sol coating before and after sunlight irradiation were measured with tensile tester. XRD pattern of titanium dioxide particles was observed by mixing phase together with rutile and anatase type. The results showed, after sunlight irradiation, the decreased mechanical properties of the fiber. Furthermore, the sunlight irradiation obviously deteriorated the surface and defected areas of the fiber severely by photo-induced chain scission and end group oxidation in air.

Partial Discharge Phenomenon with $SF_6$ Gas Pressures in Insulation consisting of Insulation Paper and $SF_6$ Gas (SF_6 가스와 절연지의 절연계에서 가스압력에 따른 부분방전현상)

  • 선종호;김광화;박정후;조정수
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.50 no.2
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    • pp.65-71
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    • 2001
  • This paper describes partial discharge phenomenon with SF6gas pressures in insulation consisting of insulation paper and SF6 gas. We made the specimens with SF6 gas gaps which exist between aramid papers and electrodes and calculated the electric field intensity in the these gaps. We measured the partial discharge inception voltages and the AC breakdown voltages with the test method of IEC 60060-2 and did the partial discharge degradation experiments with a constant voltage. According to gas pressures, the breakdown voltages in SF6gas gaps were calculated by Paschen's law. And these results showed the ability applying partial discharge inception voltages evaluation to Paschen's law and the relationship between the PD quantities occurring insulation breakdown and PD occurring area.

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Capacity Development of Existing Frame by Aramid Sheet and Energy Dissipation Device (아라미드 시트와 에너지 소산 장치에 의한 기존 골조의 능력 향상)

  • Lee, Hyun-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.5
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    • pp.112-119
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    • 2015
  • In this paper, the strengthening method was proposed for improving the seismic performance of the vulnerable structural frames. To improve the brittle characteristics of columns, aramid fiber sheet was used for the lateral confinement of columns. And to introduce the energy dissipation capacity, a steel damper with S-shaped struts was installed. By making the unreinforced and reinforced specimens with full size specimens were evaluated for lateral load resistance capacity. It was confirmed the strengthening effects by the evaluation of failure shape, strength, stiffness degradation, and energy dissipation capacity. Also from the FE analysis using ABAQUS, the hysteretic behavior of the specimens were predicted and evaluated.

Experimental Study on Interfacial Bond Stress between Aramid FRP Strips and Steel Plates (아라미드 FRP 스트립과 강판 사이의 계면 부착응력에 관한 실험적 연구)

  • Park, Jai Woo;Ryoo, Jae Yong;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.27 no.4
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    • pp.359-370
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    • 2015
  • This paper presents the experimental results for the interfacial bond behaviour between AFRP strip and steel members. The objective of this paper is to examine the interfacial behavior and to evaluate the interfacial bond stress between Aramid FRP strips and steel plates. The test variables were bond length and AFRP thickness. 18 specimens were fabricated and one-face shear type bond tests were conducted in this study. There were two types of failure mode which were debonding and delamination between AFRP strip and steel plates. From the test, the load was increased with the increasing of bond length and AFRP thickness, which was observed that maximum increase of 63 and 86% were also achieved in load with the increasing of bond length and AFRP thickness, respectively. Finally, bond and slip characteristics had the elastic bond-slip model and it was observed that bond strength and fracture energy were not affected by bond length and AFRP thickness.

Experimental study on reinforced high-strength concrete short columns confined with AFRP sheets

  • Wu, Han-Liang;Wang, Yuan-Feng
    • Steel and Composite Structures
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    • v.10 no.6
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    • pp.501-516
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    • 2010
  • This paper is aiming to study the performances of reinforced high-strength concrete (HSC) short columns confined with aramid fibre-reinforced polymer (AFRP) sheets. An experimental program, which involved 45 confined columns and nine unconfined columns, was carried out in this study. All the columns were circular in cross section and tested under axial compressive load. The considered parameters included the concrete strength, amount of AFRP layers, and ratio of hoop reinforcements. Based on the experimental results, a prediction model for the axial stress-strain curves of the confined columns was proposed. It was observed from the experiment that there was a great increment in the compressive strength of the columns when the amount of AFRP layers increases, similar as the ultimate strain. However, these increments were reduced as the concrete strength increasing. Comparisons with other existing prediction models present that the proposed model can provide more accurate predictions.