• Title/Summary/Keyword: Equivalent Strain

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Numerical Studies of Subsidence and Hydraulic Conductivity Enhancement Due to Underground excavation (지하 굴착에 의한 침하와 수리전도도 증가에 관한 수치해석적 연구)

  • Yoon, Yong-Kyun
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 2000.09a
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    • pp.139-146
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    • 2000
  • This study investigates the changes of subsidence and hydraulic conductivity by underground mining. Coupling between post-mining induced strains and strain-dependent hydraulic conductivities is obtained by idealizing a jointed rock mass as an equivalent porous medium in which the hydraulic conductivity of a single joint is defined through parallel plate description. Results indicate that post-mining hydraulic conductivities are directly related to the strain field occurred by subsidence induced deformation. Maximum subsidence and hydraulic conductivity values increase as a panel width does widen. Joint spacing has an effect on the intensity of the changes in hydraulic conductivity.

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Numerical Studies of Subsidence and Hydraulic Conductivity Enhancement Due to Underground Excavation (지하 굴착에 의한 침하와 수리전도도 증가에 관한 수치해석적 연구)

  • 윤용균
    • Tunnel and Underground Space
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    • v.10 no.3
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    • pp.387-394
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    • 2000
  • This is study investigates the changes of subsidence and hydraulic conductivity by underground mining Coupling between post-mining induced strains and strain-dependent hydraulic conductivities is obtained by idealizing a jointed rock mass as an equivalent porous medium in which the hydraulic conductivity of a single joint is defined through parallel plate description. Results indicate that post-mining hydraulic conductivities are directly related to the strain field occurred by subsidence induced deformation. Maximum subsidence and hydraulic conductivity values increase as a panel width does widen. Joint spacing has an effect on the intensity of the changes in hydraulic conductivity.

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Modeling of a Ductile Fracture Criterion for Sheet Metal Considering Anisotropy (판재의 이방성을 고려한 연성파단모델 개발)

  • Park, N.;Huh, H.
    • Transactions of Materials Processing
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    • v.25 no.2
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    • pp.91-95
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    • 2016
  • This paper is concerned with modeling of a ductile fracture criterion for sheet metal considering anisotropy to predict the sudden fracture of advanced high strength steel (AHSS) sheets during complicated forming processes. The Lou−Huh ductile fracture criterion is modified using the Hill’s 48 anisotropic plastic potential instead of the von Mises isotropic plastic potential to take account of the influence of anisotropy on the equivalent plastic strain at the onset of fracture. To determine the coefficients of the model proposed, a two dimensional digital image correlation (2D-DIC) method is utilized to measure the strain histories on the surface of three different types of specimens during deformation. For the derivation of an anisotropic ductile fracture model, principal stresses (𝜎1,𝜎2, 𝜎3) are expressed in terms of the stress triaxiality, the Lode parameter, and the equivalent stress (𝜂𝐻, 𝐿,) based on the Hill’s 48 anisotropic plastic potential. The proposed anisotropic ductile fracture criterion was quantitatively evaluated according to various directions of the maximum principal stress. Fracture forming limit diagrams were also constructed to evaluate the forming limit in sheet metal forming of AHSS sheets over a wide range of loading conditions.

Flexure of cross-ply laminated plates using equivalent single layer trigonometric shear deformation theory

  • Sayyad, Atteshamuddin S.;Ghugal, Yuwaraj M.
    • Structural Engineering and Mechanics
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    • v.51 no.5
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    • pp.867-891
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    • 2014
  • An equivalent single layer trigonometric shear deformation theory taking into account transverse shear deformation effect as well as transverse normal strain effect is presented for static flexure of cross-ply laminated composite and sandwich plates. The inplane displacement field uses sinusoidal function in terms of thickness coordinate to include the transverse shear deformation effect. The cosine function in thickness coordinate is used in transverse displacement to include the effect of transverse normal strain. The kinematics of the present theory is much richer than those of the other higher order shear deformation theories, because if the trigonometric term (involving thickness coordinate z) is expanded in power series, the kinematics of higher order theories (which are usually obtained by power series in thickness coordinate z) are implicitly taken into account to good deal of extent. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. The closed-form solutions of simply supported cross-ply laminated composite and sandwich plates have been obtained. The results of present theory are compared with those of the classical plate theory (CPT), first order shear deformation theory (FSDT), higher order shear deformation theory (HSDT) of Reddy and exact three dimensional elasticity theory wherever applicable. The results predicted by present theory are in good agreement with those of higher order shear deformation theory and the elasticity theory.

Fatigue life evaluation for fuselage structure using equivalent unit load (등가 단위하중을 이용한 동체 구조물 피로수명 평가)

  • Kim, Sung-Joon;Ahn, Seok-Min;Yeom, Chan-Hong
    • Aerospace Engineering and Technology
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    • v.8 no.2
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    • pp.13-18
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    • 2009
  • In this study, an equivalent unit load methodology has been presented to simplify the fatigue analysis procedure. And fuselage structure fatigue life has been evaluated based on equivalent unit load. Finite element analysis has been carried out to analyze the stress intensity factor and geometrical correction factor that is needed for crack growth analysis. And strain energy density factor is used to predict the initial direction of crack propagation.

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Structural Safety Analysis on Crack Propagation in Compact Tension Specimen (소형 인장 시험편 내의 크랙 전파에 대한 구조 안전해석)

  • Cho, Jae-Ung
    • Journal of the Korea Convergence Society
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    • v.5 no.1
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    • pp.23-27
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    • 2014
  • In case eccentric load is applied at compact tension specimen, the propagation behavior due to existence or nonexistence of hole, numbers and positions of holes near crack is investigated in this study. Strain energy, displacement and stress happened in specimen are examined through simulation analysis. And stress intensity factor is obtained by the basis of strain energy and deformation. When defect or hole exists in structure, the possibility of fracture can be thought to be verified by using the study result.

Approximate residual stress and plastic strain profiles for laser-peened alloy 600 surfaces

  • Eui-Kyun Park ;Hyun-Jae Lee ;Ju-Hee Kim ;Yun-Jae Kim
    • Nuclear Engineering and Technology
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    • v.55 no.4
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    • pp.1250-1264
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    • 2023
  • This paper presents approximate in-depth residual stress and plastic strain profiles for laser-peened alloy 600 surface via FE analysis. In approximations, effects of the initial welding residual stress and the number of shots are quantified. Based on FE analysis results, residual stress profiles are quantified by two variables; the maximum difference in stress before and after LSP, and the depth up to which the compressive residual stress exists. Plastic strain profiles are quantified by one variable, the maximum equivalent plastic strain at the surface. The proposed profiles are validated by comparing with published LSP experimental results for welded plates. Effects of the initial welding residual stress and the number of shots on these variables are discussed. The proposed profile can be directly applied to predict the mitigation effect of LSP on PWSCC and to efficiently perform structural integrity assessment of laser peened nuclear components.

Anisotropic Continum Damage-Plastic Model for Concrete (콘크리트의 이방성 손상-소성 모델)

  • 변근주;송하원;이기성;김종우
    • Proceedings of the Korea Concrete Institute Conference
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    • 1994.04a
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    • pp.91-96
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    • 1994
  • The growth and propagation of microcracks existed in concrete cause failure of concrete. This is called "damage". The concepts of two principles, equivalent strain principle and equivalent energy principle, are reviewed and compared in the case of uniaxial compressior to concrete. The damage evolution law and constitutive equation are derived by using the Helmholz free energy and the dissipation potential by means of the thermodynamic principles.rinciples.

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Study on the Relationships of Bending Moment-Corvature Based on Bond Property (부착특성을 고려한 휨모멘트-곡률 관계에 관한 연구)

  • 장일영
    • Proceedings of the Korea Concrete Institute Conference
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    • 1991.04a
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    • pp.81-85
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    • 1991
  • The object of this study is to propose the bending moment-curvature relationships based on the bond properties between concrete and steel for noncraking zone, and evaluate the flexural displacement of reinforced concrete members. The bond-slip relationship and the strain hardening effect of steel were taken into account in order to evaluate the spacing of the cracks and the curvature distribution. Calculated curvature distribution along the longitudinal axis was transformed into equivalent curvature distribution. The flexural displacement was calculated by means of double intergral of the equivalent curvature. Calculated values are in good agreement with the experimental data.

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Equivalent Continuum Model for the Single Wall Carbon Nanotube (Single Wall Carbon Nanotube의 등가 연속체 모델에 대한 연구)

  • 김병구;전흥재
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.227-234
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    • 2003
  • In this study, an equivalent continuum model for single wall carbon nanotube is proposed. The model links interatomic potentials and atom structure of a materials to a constitutive model on the continuum level. The Young's modulus and shear modulus were predicted by the model. The predictions were in good agreement with the prior experimental results available in the literatures. Also, the strain energy of the carbon nanotube was predicted as a function of the radius of the carbon nanotube.

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