• 제목/요약/키워드: Effective Elastic Constant

검색결과 47건 처리시간 0.021초

포화된 정규압밀 점성토에서 비배수 공극수압의 거동(II) - 점탄성 해석 모델 - (The Behavior of Undrained Pore Water Pressure in Normally Consolidated and Saturated Clay(II) - Visco Elastic Analysis Model -)

  • 임성훈
    • 한국농공학회지
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    • 제45권4호
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    • pp.137-143
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    • 2003
  • The initial condition of $\Delta \sigma_3 \;=\; \Delta u$ is used for analyzing the time dependent behavior of ground. This is based on the concept that the coefficient of pore water B is the unity on the condition of saturation. but some measured consolidation data in the field showed that the pore water pressure was not dissipated as time elapsed but it was maintained constant value or it's dissipation rate was slower than that of the predicted. and so the measured data of pore water pressure was not consistent with that of settlement. In this study, the rheological model for the pore water pressure behavior on undrained condition was induced and compared with the experiment data of the literature. The result showed that the suggested model was consistent well with the result of experiment, but the suggested model could not explain the effect of the decrease of void ratio according to consolidation.

5083-H113 알루미늄合金의 表面균열進展擧動과 균열닫힘 現象 (Surface crack propagation behavior and crack closure phenomena in 5083-H113 aluminum alloy)

  • 박영조;김정규;신용승;김영운
    • 대한기계학회논문집
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    • 제11권2호
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    • pp.243-252
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    • 1987
  • 본 논문에서는 작은 인공결함을 가진 표면균열의 진전거동을 밝히기 위하여 용접성이 좋고 강도도 적당하며 내식성이 좋아 해양구호무재 및 용접구호물재로서 널 리 사용되는 5083-H113 알루미늄합금을 준비하고 이재료의 피로표면균열 진전거동에 미치는 응력비의 영향을 균열닫힘과 함께 검토하였다.

합성단면의 콘크리트 크리프 효과에 대한 일반화 매개변수의 민감도 분석 (Sensitivity Analysis of Generalized Parameters on Concrete Creep Effects of Composite Section)

  • 연정흠;김의헌
    • 콘크리트학회논문집
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    • 제21권5호
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    • pp.629-638
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    • 2009
  • 합성단면을 구성하는 콘크리트 단면에 크리프에 의한 장기변형이 발생되면 합성단면에는 추가의 변형이 발생되며 콘크리트 단면에는 장기변형의 일부구속으로 잔류응력이 발생한다. 이 논문에서는 복잡한 합성단면에서 콘크리트 단면의 장기변형에 대한 반응을 평가하는 기존의 단계별계산법을 보다 효율적으로 적용할 수 있도록 일반화 하였다. 장기변형이 발생하는 콘크리트 단면과 이 변형의 일부를 구속하는 구속단면의 단면특성과 재료특성으로부터 초기 합성단면의 환산단면특성이 유도되고, 각 단계의 크리프계수가 고려된 유효탄성계수가 적용된 환산 단면특성이 유도되었다. 합성단면의 일반화 반응에 대한 5개의 일반화 매개변수로 구성된 단계별계산법의 식이 유도되었다. 각 단계별 계산식에는 크리프계수의 증가가 일정하도록 하여 식의 단순화와 계산시간의 감축 및 균등한 단계별 계산오차가 가능한 균등 크리프 단계별계산법을 제안하였다. 콘크리트 단면의 초기 축방향 탄성 변형률에 대한 일반화 반응은 콘크리트 단면적의 비율에 가장 민감하고, 콘크리트 단면의 단면이차모멘트 비율보다는 구속단면의 단면이차모멘트 비율에 보다 민감하였다. 반면에 콘크리트 단면의 초기 탄성곡률에 대해서는 콘크리트 단면의 단면이차모멘트 비율에 가장 민감하였다.

코드섬유-고무 복합재료의 물성치에 대한 계면의 영향 (Effect of Interface on the Properties of Cord-Rubber Composites)

  • 임현우;김종국;염영진
    • 대한기계학회논문집A
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    • 제34권5호
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    • pp.583-588
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    • 2010
  • 고무의 비선형성과 대변형으로 인해 코드-고무 복합재료의 정확한 거동을 파악하기는 어렵다. 코드와 고무 사이에 제 3 의 상을 가정해서 세 가지 상에 대한 모델링을 하기도 하지만 코드-고무 복합재료 계면의 두께와 물성을 결정하기 힘들다. 본 연구에서는 2 차원 일반화된 평면변형률요소와 평면변형률요소를 사용한 유한요소법을 적용하여 여러 가지 계면 두께를 갖는 코드-고무 복합재료의 유효탄성계수와 무차원 탄성계수를 구하였다. 고무물성은 네오-후크 모델을 적용하였고 여러 가지 하중상태와 몇 가지 계면 물성치에 대한 고찰을 하였다. 그 결과 계면 물성치와 계면 두께는 코드-고무 복합재료의 비선형성과 유효탄성계수에 영향을 미침을 알수 있었다.

유한요소해석을 이용한 SBP 시험의 결과해석 - 점성토 지반의 압밀특성 (Numerical analysis of Self-Boring Pressuremeter test results using FEM - Consolidation characteristics of clay)

  • 장인성;정충기
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 1999년도 가을 학술발표회 논문집
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    • pp.67-74
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    • 1999
  • Self-Boring Pressuremeter Test(SBPT) is known to be the most effective in-situ test method which can reliably determine consolidation characteristics as well as deformation modules and untrained shear strength. In order to derive the coefficient of consolidation using SBPT results it is necessary to obtain the dissipation behavior from the pore pressure change with time during constant radial strain(generally 10%) and to derive the reliable time factor(Τ) from the analytical method which considers the real in-situ conditions. As previous studies on time factor are based on the assumptions of plane strain condition that the membrane of SBP is infinite, of untrained condition during the expansion of the probe and of elastic soil behavior during consolidation, these analyses can't consider the real boundary conditions and the real soil behaviour. In this study, consolidation analysis similar to real in-situ conditions including test procedure is conducted using finite element program which employs MCC model and Biot theory. Time factor considering the effects of finite membrane length, the total pressure change during consolidation and partial drainage is proposed and compared with previous results.

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Experimental and numerical study about seismic retrofitting of corrosion-damaged reinforced concrete columns of bridge using combination of FRP wrapping and steel profiles

  • Afshin, Hassan;Shirazi, Mohammad R. Nouri;Abedi, Karim
    • Steel and Composite Structures
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    • 제30권3호
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    • pp.231-251
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    • 2019
  • In the present study, a numerical and experimental investigation has been carried out on the seismic behavior of RC columns of a bridge which damaged under corrosive environments and retrofitted by various techniques including combined application of CFRP sheets and steel profiles. A novel hybrid retrofitting procedure, including the application of inner steel profiles and outer peripheral CFRP sheets, has been proposed for strengthening purpose. Seven large-scale RC columns of a Girder Bridge have been tested in the laboratory under the influence of simultaneous application of constant axial load and the lateral cyclic displacements. Having verified the finite element modeling, using ABAQUS software, the effects of important parameters such as the corrosion percentage of steel rebars and the number of CFRP layers have been evaluated. Based on the results, retrofitting of RC columns of the bridge with the proposed technique was effective in improving some measures of structural performance such as lateral strength degradation and higher energy absorption capability. However, the displacement ductility was not considerably improved whereas the elastic stiffness of the specimens has been increased.

유공압 회로를 이용한 자전거 포크용 가변댐퍼-공압스프링 서스펜션의 해석 (Analysis of a Variable Damper and Pneumatic Spring Suspension for Bicycle Forks using Hydraulic-Pneumatic Circuit Model)

  • 장문석;최영휴;김수태;최재일
    • 드라이브 ㆍ 컨트롤
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    • 제16권1호
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    • pp.7-13
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    • 2019
  • The objective of this study was to present a damped pneumatic suspension, a bike fork suspension, which can adapt itself to incoming road excitations is presented in this paper. It consists of a hydraulic damper and a pneumatic spring in parallel with a linear spring. The study also proposed a variable and switchable orifice, in the hydraulic damper, to select appropriate damping property. Hydraulic-pneumatic circuit model for the bike fork suspension was established based on AMESim, in order to predict its performance. In addition, elastic-damping characteristics of the fork such as spring constant and viscous damping coefficient were computed and compared, for validation, with those evaluated by experiment using the universal test machine. Through simulation analysis and test, it was established that the hydraulic-pneumatic circuit model is effective and practical for development of future MTB suspensions.

Kaolin충전제(充塡劑) 표면처리(表面處理)에 관(關)한 硏究(연구) (제3보(第3報)) - 첨가(添加)된 충전제充塡劑)와 고무Matrix와의 Interaction 및 충전제(充塡劑) 보강효과(補强效果)의 특성화(特性化) - (Studies on Surface Treatment of Kaolin Filler (Part 3) - Interaction between Surface Modified Filler and Rubber Matrix and Characterization of Reinforcement Effects of Filler -)

  • 권동용;홍성일
    • Elastomers and Composites
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    • 제20권1호
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    • pp.25-39
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    • 1985
  • Elastomer-filler interaction in terms of characterization of filler effects was studied using natural rubber(NR) loaded with kaolin fillers modified with sodium polyphosphate and poly(maleic anhydride), respectively. Kaolins modified with sodium polyphosphate or poly(maleic anhydride) show adhering characteristics by Kraus plot. Reinforcement activity according to Cunneen-Russell method is given by those fillers, in which sodium polyphosphate-treated kaolin presents more favorable results than that treated with poly(maleic anhydride) with respect to adhesion constant, reinforcement extent, elastic constant, and crosslink density. When applied to Blanchard's linkage reinforcement theory, NR vulcanizates loaded with kaolin modified with sodium polyphosphate meet the requirements for both approximate linkage reinforcement(${\psi}'$) of 1.02 to 4.94 and accurate linkage reinforcement($\psi$) of 1.00 to 1.18, representing the values of effective wetting($C_{\psi}$) for 0.001 to 0.029 and intrinsic linkage reinforcement(${\psi}_0$) for 1.015 to 1.124, respectively, whille negligible linkage reinforcement is shown by NR vulcanizates loaded with kaolin treated with poly(maleic anhydride). Dynamic storage modulus(G') given by surface modified kaolins presents more favorable crosslink density rates of $2.260{\times}10^{-5}\;mole/cm^3-min$. for sodium polyphosphate treated kaolin and $1.305{\times}10^{-5}\;mole/cm^3-min$. for poly(maleic anhydride) treated kaolin, respectively, compared to untreated kaolin showing the rate of $1.033{\times}10^{-5}\;mole/cm^3-min$.

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온양지역에 분포하는 호상편마암을 이용한 평면 이방성 암석의 탄성상수 측정방법 (Method of Elastic Constant Measurement for Transversely Isotropic Rocks: Application to Banded Gneiss of the Onyang Region)

  • 장현식;이옥탑;장보안
    • 지질공학
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    • 제22권3호
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    • pp.309-321
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    • 2012
  • 충청남도 온양지역에서 채취한 호상편마암으로부터 $0^{\circ}$ 시료 9개, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$ 시료 각 10개, $60^{\circ}$, $75^{\circ}$ 시료 각 11개, $0^{\circ}$ 시료 9개를 획득하여 총 70개의 시료를 이용해 이방성 탄성상수를 측정하였다. 이방성 각 $0^{\circ}$, $90^{\circ}$ 시료에서 측정된 탄성상수($E_1$, $E_2$, ${\nu}_{12}$, ${\nu}_{21}$)를 기준값으로 설정하고 Jang et al. (2001)과 Park et al. (2008)에 의해 제안된 방법을 이용하여 $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $75^{\circ}$ 시료의 탄성계수($E_1$, $E_2$)를 계산한 후 기준값과 비교하였다. Jang et al. (2001)의 제안법을 사용할 경우 $60^{\circ}$, $75^{\circ}$와 같은 고각의 이방성 시료에서는 $E_1$이 비교적 정확하게 계산되고 $15^{\circ}$, $30^{\circ}$와 같은 저각의 이방성 시료에서는 $E_2$가 비교적 정확하게 계산되었다. Park et al. (2008)의 제안법의 경우 $E_1$$45^{\circ}$$60^{\circ}$ 시료에서만 비교적 정확한 값을 계산해냈고 $E_2$$15^{\circ}$, $30^{\circ}$, $60^{\circ}$ 시료에서 비교적 정확하게 계산되었다. 유효성 검토 결과 두 제안법 모두 총 20개의 유효성 판단구간에서 '유효함(Effective)' 7개(35%), '가능함(Possible)' 5개(25%), '유효하지 않음(Ineffective)' 8개(40%)로 분석되어 두 제안법의 유효성은 같은 수준이었다. 다만 Jang et al. (2001)의 제안법은 $E_1$을, Park et al. (2008)의 제안법은 $E_2$를 계산하는데 상대적으로 더 유효한 것으로 분석되었다.

7075-T651 AI 합금에 있어서 물리적 미소 표면 피로균열 성장거동에 관한 연구 (A Study on Physically small Surface Fatigue Crack Growth Behavior in 7075-T651 Aluminum Alloy)

  • 신용승;서성원;유헌일
    • 한국정밀공학회지
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    • 제9권1호
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    • pp.106-117
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    • 1992
  • In this study, the propagation behaviour and the closure phenomena of physically small surface cracks were investigated by the techinque of the Kikukawa-unloading elastic compliance method using a back face strain gage. The surface cracks initiated and propagated from notched specimens under constant amplitude bending load. The crack shape (aspect ratio) with approximately semi-circular at the early stage was changed to semi-elliptical as the cracks grew larger. The crack depth (a) could be expressed uniquenly by the crack length (c). The dependence of the crack propagation rate on the stress ratio R was strongly related in the lower ${\Delta}K$ range. The deceleration of the surface crack propagation rate was prominent in lower R during the crack length was small. When the propagation rate was rearranged with the effective stress intensity factor range ${\Delta}$K_{eff} the dependence of the crack propagation rate on the stress ratio R was found to be diminshed. These were caused by the crack closure phenomena that was most prominent at the lower propagation rate. The mechanism of crack closure phenomena was dominated by the plasticity-induced mechanism.

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