• 제목/요약/키워드: Elastic Factor

검색결과 825건 처리시간 0.024초

CLS 시편의 탄성일인자 유도 및 이를 적용한 열가소성 Graphite/Peek 복합재의 파괴인성 $G_c$ 측정 (Elastic Work Factor of CLS Specimen and Determination of $G_c$ for Graphite/Peek Composites by Using the Elastic Work Factor)

  • 이경엽
    • 대한기계학회논문집A
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    • 제20권9호
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    • pp.2792-2799
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    • 1996
  • It was shown in the previous study that the numerically derived elastic work factor for CLS specimen was independent of fiber direction for a unidirectional case. Also, it was proposed the elastic work factor could be used to determine energy release rate from a single test record. In the present study, elastic work factor was derived from a simple beam theory to investigate its dependence on material property and geometric condition. Also, the elastic work factor of CLS specimen was applied experimentally to determine critical energy release rate in order to prove its validity determining critical energy release rate from a single specimen. For this purpose, critical energy release rate determined using the elastic work factor was compared with that determined by the compliance method. The results showed that while elastic work factor is affected by $t_2/t_1$ and $L_2/L_1$ it is independent of fiber angle for a unidirectional case. It was also found that critical energy release rates determined by both methods are comparable each other, thus elastic work factor approach can be used to determine energy release rate from a single test specimen.

탄성일인자방법을 적용한 단일방향 탄소섬유/에폭시 DCB 시편의 파괴인성 결정 ($G_IC$ determination of unidirectional graphite /epoxy DCB composites from the elastic work factor approach)

  • 이경엽;이중희
    • 대한기계학회논문집A
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    • 제22권3호
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    • pp.540-544
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    • 1998
  • Compliance calibration method is frequently used to determine $G_IC$ from the DCB composite specimen. However, the method requires at least 4 to 5 fracture test (loading-unloading) records. In this study, $G_IC$ of unidirectional graphite/epoxy DCB composites was determined from the elastic work factor approach which uses a single fracture test record. In order to inspect the validity of the elastic work factor approach, $G_IC$ determined from the elastic work factor approach was compared to that of determined from the compliance calibration method. It was shown that $G_IC$ determined from the elastic work factor approach was comparable to that determined from the compliance calibration method. That is, the elastic work factor approach can be used to determine $G_IC$ of unidirectional graphite/epoxy DCB specimen from a single fracture record.

정수압이 탄소섬유/에폭시 복합재의 탄성일인자에 미치는 영향 (Effect of Hydrostatic Pressure on the Elastic Work Factor of Graphite/Epoxy Composites)

  • 이지훈;김만태;신명근;한운용;이경엽
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1390-1393
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    • 2003
  • Work factor approach is conveniently used in metal fracture mechanics to determine fracture toughness from a single fracture test. In this work, we investigated the applicability of the work factor approach in order to determine fracture toughness of thick graphite/epoxy composites in the hydrostatic pressure environment from a single fracture test. The effect of hydrostatic pressure on the elastic work factor was studied, The stacking sequence used was multi-directional, [0$^{\circ}$/${\pm}$45$^{\circ}$/90$^{\circ}$]. The hydrostatic pressures applied were 0.1 MPa, 100 MPa, 200 MPa, and 300 MPa. The results showed that the elastic work factor was not affected by the hydrostatic pressure, The elastic work factor decreased in a linear fashion with crack length.

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탄성에폭시 블렌드 시스템의 열적 특성 및 내충격성에 관한 연구 (Study on the Thermal Properties and High Impact of Elastic Epoxy Blend System)

  • 이경용;이관우;민지영;최용성;박대희
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제53권4호
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    • pp.192-199
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    • 2004
  • Elastic-factor of elastic epoxy were investigated by TMA (Thermomechanical Analysis), DMTA (Dynamic Mechanical Thermal Analysis), TGA (Thermogravimetric Analysis) and FESEM (Field Emission Scanning Electron Microscope) for structure-images analysis as toughness-investigation to improve brittleness of existing epoxy resin. A range of measurement temperature of the TMA and DMTA was changed from -20($^{\circ}C$) to $200^{\circ}(C)$, and TGA was changed from $0^{\circ}(C)$ to $600^{\circ}(C)$. Glass transition temperature (Tg) of elastic epoxy was measured through thermal analysis devices with the content of 0(phr), 20(phr) and 35(phr). Also, thermal expansion coefficient (a), high temperature, modulus and loss factor were investigated through TMA, TGA, and DMTA. In addition, the structure of specimens was analyzed through FESEM, and then elastic-factor of elastic epoxy was visually showed by FESEM. As thermal analysis results, 20(phr) was more excellent than 30(phr) thermally and mechanically. Specially, thermal expansion coefficient, high temperature, modulus, and damping properties were excellent. By structure-images analysis through FESEM, we found elastic-factor of elastic epoxy that is not existing epoxy, and proved high impact.

중간탄성지점이 있는 부분고정단 압축재의 고유치 문제에 관한 연구 (A Study on the Eigenvalue Problems of Partially Fixed End Members with Intermediate Elastic Supports)

  • 김순철;문연준;이수곤
    • 소음진동
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    • 제8권2호
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    • pp.297-305
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    • 1998
  • The finite element method is used for the study of the eigenvalue problems of partially fixed end beams with intermediate elastic supports. The elastic critical loads and natural frquencies of the beams are investigated by changing the numbers of elastic supports and their stiffness, and also by changing Kinney's fixity factor, $f_a$. The relationship between two eigenvalues is established by calculating the corresponding values of $(w/w_n)^2$ through changing $(P/P_{cr})$ values. The results of this study are as follows : (1) The elastic critical loads and natural frequencies of beams increase with increases in Kinney's fixity factor, $f_a$ and with the increased numbers of intermediate elastic supports. (2) The relationship between elastic critical loads and the natural frequencies of partially fixed end beams with intermediated elastic supports is $P/P_{cr} + (w/w_n)^2/ = 1$ without regard to Kinney's fixity factor, the stiffness of elastic supports, or the number of elastic supports.

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정수압을 받는 일방향 탄소섬유/에폭시 복합재의 파괴인성 결정을 위한 일인자 적용 (Application of Work Factor to Determine Fracture Toughness of Unidirectional Graphite/Epoxy Composites under Hydrostatic Pressure)

  • 이경엽
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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    • pp.46-49
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    • 2001
  • In this paper. tile validity of work factor approach was investigated to determine compressive fracture toughness of unidirectional graphite/epoxy composites under hydrostatic pressure environment. The elastic work factor was determined under various pressures as a function of delamination length. It was found that elastic work factor was not affected by hydrostatic pressure.

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취성 개량형 탄성에폭시의 구조 및 열적특성에 관한 연구 (Study on the Structural and Thermal Properties of Modified Elastic Epoxy with Brittleness)

  • 이경용;이관우;민지영;최용성;박대희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 추계학술대회 논문집 전기물성,응용부문
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    • pp.128-130
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    • 2003
  • As toughness-investigation to improve brittleness of existing epoxy resin, elastic-factor of elastic epoxy using TMA (Thermomechanical Analysis), DMTA (Dynamic Mechanical Thermal Analysis) and FESEM (Field Emission Scanning Electron Microsope) for structure-images analysis were investigated. A range of measurement temperature of the TMA, DMTA was changed from -20[$^{\circ}C$] to 200[$^{\circ}C$]. When modifier was ratio of 0[phr], 20[phr], 35[phr], glass transition temperature (Tg) of elastic epoxy was measured through thermal analysis devices. Also, it was investigated thermal expansion coefficient ($\alpha$), modulus and loss factor through DMTA. In addition, it was analyzed structure through FSSEM and made sure elastic-factor of elastic epoxy visually. As thermal analysis results, 20[phr] was superior than 30[phr] thermally and mechanically. Specially, thermal expansion coefficient, modulus, damping properties were excellent. By structure-images analysis through FESEM, we found elastic-factor of elastic epoxy that is not existing epoxy, and proved high impact.

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彈性支持를 받는 四角多孔板의 荷重分布係數에 관한 연구 (A Study on the Load Distribution Factor in the Perforated Square Plate with Elastic Support at Four Corners)

  • 임정식;이영신
    • 대한기계학회논문집
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    • 제13권4호
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    • pp.563-571
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    • 1989
  • 본 연구에서는 이들 무시된 영향을 고려하여 하중작용점에서의 하중분포계수 를 구하여, 이 하중분포계수에 의해 위치에 따라 실제와 가까운 하중을 가하므로서 보다 엄밀한 판의 해석을 할 수 있도록 제시하였다.

섬유강화 복합재의 $G_ {IC}$ 결정을 위한 일인자방법 (Determination of Mode I Fracture Toughness of Fiber Reinforced Composites by the Elastic Work Factor)

  • 이경엽;고승기
    • 대한기계학회논문집A
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    • 제20권11호
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    • pp.3491-3497
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    • 1996
  • The work factor approach was applied to determine $G_ {IC}$ of fiber reinforced composites (AS4/3501) from a single unidirectional (0-deg) DCB specimen. Elastic work factors of DCB specimen for three different symmetrical staking sequences were derived from a simple bending theory and a finite element method. The results showed that elastic work factors calculated from both methods were comparable each other. In particular, the elastic work factor of DCB specimen with symmetrical stacking sequence is independent of stacking sequence. The $G_ {IC}$ determined from the work factor approach was compared with that determined by the compliance method. The results showed that the work factor approach and the compliance method produce comparable results of $G_ {IC}$. Thus, $G_ {IC}$ can be determined from a single DCB specimen using the work factor approach.

경계요소법에 의한 탄성-점탄성 복합구조체의 계면균열 해석 (Boundary Element Evaluation of Stress Intensity Factor for Interface Crack in Elastic and Viscoelastic Composite Materials)

  • 이상순;김정규;황종근
    • 전산구조공학
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    • 제9권1호
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    • pp.85-91
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    • 1996
  • 이 논문에서는 탄성-점탄성 복합재료의 공유면에 존재하는 계면균열에 대한 해석방법을 제시하고 있다. 먼저 탄성-점탄성 대응원리를 이용하여 탄성해석식으로부터 응력확대계수에 대한 식을 유도하였다. 다음으로 시간영역 경계요소법을 이용하여 균열선단에서의 응력을 계산한 다음 응력확대계수의 값을 구하였다. 수치해석의 결과는 본 논문의 정확성과 응용가능성을 보여준다.

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