• Title/Summary/Keyword: Composite temperature

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The Quantitative Evaluation of Aging State of Field Composite Insulators Based on Trap Characteristics and Volume Resistivity-Temperature Characteristics

  • Liang, Ying;Gao, Li-Juan;Dong, Ping-Ping;Gao, Ting
    • Journal of Electrical Engineering and Technology
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    • v.13 no.3
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    • pp.1355-1362
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    • 2018
  • In order to obtain a better understanding of the ageing process of the field composite insulators, it is necessary to explore a quantitative-valuation method for the aging state evaluation. And the linear relationship between volume resistivity and temperature is proposed. In this paper, the composite insulators with different lengths of operating lives from two manufacturers were tested. The relationship between trap characteristics and volume resistivity-temperature characteristics were analyzed based on Thermal Stimulated Current (TSC), volume resistivity-temperature test, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, the application of trap characteristics in the quantitative evaluation of aging state of composite insulators was discussed. The results showed that there was a general negative correlation between the relative variation ratio of trap charges and the volume resistivity-temperature characteristics. Meanwhile, the physicochemical properties would change with the aging time, which would result in the increasing of electron traps. Combined with the TSC and volume resistivity test results, the trap characteristic thresholds which indicated the serious age of the composite insulators had been proposed.

Thermal Strain and Temperature Measurements of Structures by Using Fiber-Optic Sensors (광섬유 센서를 이용한 구조물의 열변형 및 온도 측정)

  • 강동훈;강현규;류치영;홍창선;김천곤
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.04a
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    • pp.184-189
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    • 2000
  • Two types of fiber-optic sensors, EFPI(extrinsic Fabry-Perot interferometer) and FBG(fiber Bragg grating), have been investigated for measurement of thermal strain and temperature. The EFPI sensor is only for measurement of thermal strain and the FBG sensor is for simultaneous measurement of thermal strain and temperature. FBG temperature sensor was developed to measure strain-independent temperature. This sensor configuration consists of a single-fiber Bragg grating and capillary tube which makes it isolated from external strain. This sensor can then be used to compensate for the temperature cross sensitivity of a FBG strain sensor. These sensors are demonstrated by embedding them into a graphite/epoxy composite plate and by attaching them on aluminum rod and unsymmetric graphitelepoxy composite plate. All the tests were conducted in a thermal chamber with the temperature range $20-100^{\circ}C$. Results of strain measurements by fiber-optic sensors are compared with that from conventional resistive foil gauge attached on the surface.

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Flexural strength of concrete-galvalume composite beam under elevated temperatures

  • Maryoto, Agus;Lie, Han Ay;Jonkers, Hendrik Marius
    • Computers and Concrete
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    • v.27 no.1
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    • pp.13-20
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    • 2021
  • In this paper, the elevated temperature on a concrete-galvalume composite beam's flexural strength based on the numerical and experimental methods is investigated. The strategy is to perform modeling and simulation of the flexural test based on finite element method (FEM) at room temperature and validate its results to experimental data at the same temperature. When the numerical model was proven valid, the model was utilized to simulate the effect of elevated temperatures on the composite element. The study concludes that the flexural strength of the beam decreases at higher temperature. Additionally, it was shown that cracking moments is susceptible to temperature fluctuation and the failure modes are sensitive concerning the elevated temperature.

A Study on Temperature Distributions of Thermoset Composite in FPS Process (FPS 공정에 의한 열경화성 복합재 온도분포 연구)

  • 전영준;엄문광;변준형;이상관
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.10a
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    • pp.230-233
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    • 2003
  • Among the various manufacturing processes of composites, the tape lay-up process of thermoset prepreg has many advantages compared to autoclave or hot press forming. It has a high potential to process automation and continuous fabrication. In this study, temperature distribution of composite exposed in hot gas was studied numerically and the validity of the analysis was verified by the experiments.

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Postbuckling and nonlinear vibration of composite laminated trapezoidal plates

  • Jiang, Guoqing;Li, Fengming;Zhang, Chuanzeng
    • Steel and Composite Structures
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    • v.26 no.1
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    • pp.17-29
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    • 2018
  • The thermal effects on the buckling, postbuckling and nonlinear vibration behaviors of composite laminated trapezoidal plates are studied. Aiming at the complex plate structure and to simulate the temperature distribution of the plate, a finite element method (FEM) is applied in this paper. In the temperature model, based on the thermal diffusion equation, the Galerkin's method is employed to establish the temperature equation of the composite laminated trapezoidal plate. The geometrical nonlinearity of the plate is considered by using the von Karman large deformation theory, and combining the thermal model and aeroelastic model, Hamilton's principle is employed to establish the thermoelastic equation of motion of the composite laminated trapezoidal plate. The thermal buckling and postbuckling of the composite laminated rectangular plate are analyzed to verify the validity and correctness of the present methodology by comparing with the results reported in the literature. Moreover, the effects of the temperature with the ply-angle on the thermal buckling and postbuckling of the composite laminated trapezoidal plates are studied, the thermal effects on the nonlinear vibration behaviors of the composite laminated trapezoidal plates are discussed, and the frequency-response curves are also presented for the different temperatures and ply angles.

Prediction of Temperature and Degree of Cure of Carbon Fiber Composites Considering Thermal Chemical Reaction (화학 반응열을 고려한 탄소 섬유 복합재 온도와 경화도 예측)

  • Jae-Woo Yu;Wie-Dae Kim
    • Composites Research
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    • v.36 no.5
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    • pp.315-320
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    • 2023
  • In the manufacturing process of thermosetting carbon fiber composite materials using an autoclave, the internal temperature changes according to the set temperature cycle. This temperature change causes the resin in the composite material to cure. Heat is generated through the chemical reaction of the resin, which can result in a difference between the temperature inside the autoclave and the temperature of the composite material. Previous research assumed that the temperatures of the composite material and the autoclave were the same and analyzed to predict the residual stress and thermal deformation after manufacturing. However, these stresses and deformations depend on the temperature and degree of cure of the composite material. Therefore, this study verifies a thermal-chemical model analysis technique that takes into account the heat generated by the chemical reaction of the resin to accurately calculate the temperature and degree of cure. Additionally, case studies were conducted for different thicknesses to investigate whether this model exhibits similar trends across varying thicknesses.

Void Defects in Composite Titanium Disilicide Process (복합 티타늄실리사이드 공정에서 발생한 공극 생성 연구)

  • Cheong, Seong-Hwee;Song, Oh-Sung
    • Korean Journal of Materials Research
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    • v.12 no.11
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    • pp.883-888
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    • 2002
  • We investigated the void formation in composite-titanium silicide($TiSi_2$) process. We varied the process conditions of polycrystalline/amorphous silicon substrate, composite $TiSi_2$ deposition temperature, and silicidation annealing temperature. We report that the main reason for void formation is the mass transport flux discrepancy of amorphous silicon substrate and titanium in composite layer. Sheet resistance in composite $TiSi_2$ without patterns is mainly affected by silicidation rapid thermal annealing (RTA) temperature. In addition, sheet resistance does not depend on the void defect density. Sheet resistance with sub-0.5 $\mu\textrm{m}$ patterns increase abnormally above $850^{\circ}C$ due to agglomeration. Our results imply that $sub-750^{\circ}C$ annealing is appropriate for sub 0.5 $\mu\textrm{m}$ composite X$sub-750_2$ process.

Investigations of Temperature Effect on the Conduction Mechanism of Electrical Conductivity of Copolymer/Carbon Black Composite

  • El Hasnaoui, M.;Kreit, L.;Costa, L.C.;Achour, M.E.
    • Applied Microscopy
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    • v.47 no.3
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    • pp.121-125
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    • 2017
  • This study deals the prediction of temperature effect on low-frequency dispersion of alternating current (AC) conductivity spectra of composite materials based on copolymer reinforced with carbon black (CB) particles. A sample of ethylene butylacrylate loaded with 13% of CB particles were prepared and investigated using the impedance spectroscopy representation in the frequency range from 40 Hz to 0.1 MHz and temperature range from $20^{\circ}C$ to $125^{\circ}C$. The dielectric constant, ${\varepsilon}^{\prime}$, and dielectric losses, ${\varepsilon}^{{\prime}{\prime}}$, were found to decrease with increasing frequency. The frequency dependence of the AC conductivity follows the universal power law with a large deviation in the high frequency region, the positive temperature coefficient in resistivity effect has been observed below the melting temperature which makes this composite potentially remarkable for industrial applications.

Selection Methodology of Tool for Co-cured Composite Materials (동시경화용 복합재료의 특성에 따른 금형의 선택방법)

  • 홍중표;이종옥;이원곤;홍정수;지우석;조한준
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.10a
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    • pp.183-188
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    • 2002
  • Co-cured composite materials has its own characteristics, so its thermal expansion is different each other. The selection of tool material for co-cured composite part in high temperature more over $350^{circ}F$ and 50 Psi pressure have to consider part thermal expansion, size, shape, and economic aspect in production line. So it is important choose tooling material in manufacturing composite parts. We called the tool for airplane composite parts as BAJ (Bonding Assembly Jig). Composite parts are cured on the BAJ in autoclave. BAJ have to stable at high temperature over $350^{circ}F$ and 50 Psi pressure, Considering composite parts' dimensional tolerance compare to heat up in autoclave. This paper come from the results of the experiment at the composite parts production line and review other aircraft company's method for tooling This is for the engineer engaged in composite parts manufacturing.

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A Study on Electromagnetic Wave Absorbing Properties of $Ni_{0.6}-A_{0.1}-Zn_{0.3}{\cdot}Fe_2O_4$ Ferrite-Rubber Composite by Heat-Treatment Temperature of Ferrite (전파흡수체용 $Ni_{0.6}-A_{0.1}-Zn_{0.3}{\cdot}Fe_2O_4$의 열처리 온도에 따른 Ferrite-Rubber Composite의 전파흡수특성)

  • Park, Youn-Joon;SaGong, Geon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05b
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    • pp.155-161
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    • 2000
  • In this paper, we studied the relation between heat-treatment temperature of ferrite and electromagnetic wave absorbing properties of ferrite-rubber composite. The heat-treatment temperatures of ferrite are 1200 and $1300^{\circ}C$, 2 hr. As s result. it has been shown that the optimum heat-treatment temperature of ferrite for electromagnetic wave absorber are related to the chemical composition. And, we can control electromagnetic wave absorbing properties of ferrite-rubber composite by the control of heat-treatment temperature of ferrite.

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