• Title, Summary, Keyword: 응력세기계수

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The Curved Interfacial Crack Analysis between Foam and Composite Materials under Anti-plane Shear Force (반평면 전단하중력하에서 곡면형상 접합면을 가지는 폼과 복합재료 접합부의 계면크랙에 관한 연구)

  • 박상현;전흥재
    • Composites Research
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    • v.13 no.4
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    • pp.67-74
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    • 2000
  • The general solution of the anti-plane shear problem for the curved interfacial crack between viscoelastic foam and composites was investigated with the complex variable displacement function. Kelvin-Maxwell three parameter model is used to present viscoelasticity and the Laplace transform was applied to treat the viscoelastic characteristics of foam in the analysis. The stress intensity factor near the interfacial crack tip was predicted by considering both anisotropic and viscoelastic properties of two different materials. The results showed that the stress intensity factor increased with increasing the curvature of the curved interfacial crack and it also increased and eventually converged to a specific value with increasing time. The stress intensity factor increased with increasing the ratio of stiffness coefficients between foam and composites and the effect of fiber orientation on the stress intensity factor decreased with increasing the ratio of stiffness coefficients between foam and composites.

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Two-Dimensional Approach for Stress Intensity Factor Solution of a Semi-Elliptical Crack (2차원적 해석을 통한 반타원 결함의 응력세기계수 산출)

  • Ho, Kwang-Il;Park, In-Gyu
    • Nuclear Engineering and Technology
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    • v.23 no.1
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    • pp.12-19
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    • 1991
  • An engineering approach for estimating the stress intensity factors of a semi-elliptical crack is presented. An approximate 2-dimensional approach solution for semi-elliptical crack is derived in terms of simple equation, through weight function technique, by reflecting on the physical character of cracks.

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Boundary element analysis of stress intensity factors for Z-shaped cracks (Z형상 균열의 응력세기계수에 대한 경계요소 해석)

  • 이강용;원동성;최형집
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.1
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    • pp.36-43
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    • 1987
  • Stress intensity factors are computed by the boundary element method employing the multiregion technique along with the double-point concept. To demonstrate the validity of the current method, the stress intensity factors of the well-known simple models such as a slanted edge crack and an arcular crack are determined, in advanced, which are proved to be in good agreement within 5% with the pre-existing solutions. Z-shaped cracks are analyzed with various branch crack lengths and branching angles.

Thermal Shock Stress Intensity Factor and Fracture Test (열충격 응력세기계수와 파괴실험)

  • 이강용;심관보
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.130-137
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    • 1990
  • Thermal shock stress intensity factor for an edge-cracked plate subjected to thermal shock is obtained from Bueckner's weight function method. It is shown that thermal shock stress intensity factor has maximum values with variation of time and crack length and that there is most dangerous crack length. By comparing thermal shock stress intensity factor with fracture toughness, the fracture time and critical temperature difference due to thermal shock are determined theoretically. Under constant thermal shock temperature difference, and increase of crack length is shown to increase fracture time. The theoretical fracture time is compared with experimental value measured by acoustic emission method with soda lime glass.

Determination of Thermal Shock Stress Intensity Factor for Elliptical Crack by Modified Vainshtok Weight Function Method (수정 Vainshtok 가중함수법에 의한 타원균열의 열충격 응력세기계수의 결정)

  • 이강용;김종성
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.463-474
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    • 1995
  • Modified Vainshtok weight function method is developed. The thermal shock stress intensity factors for elliptical surface cracks existed in the thin and thick walled cylinders are determined. The present results are compared with previous solutions and shown to be good agreement with them.

Bounary Element Analysis of Thermal Stress Intensity Factors for Cusp Cracks (커스프 균열에 대한 열응력세기 계수의 경계요소해석)

  • 이강용;조윤호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.119-129
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    • 1990
  • In case that the body with a cusp crack is under uniform heat flow, thermal stress intensity factors are calculated by using boundary element method with linearized body force term. The crack surface is under insulated or fixed temperature condition and the types of crack are symmetric lip and airfoil cusps. Numerical values of thermal stress intensity factors for a Griffith crack and cusp cracks in infinite bodies are proved to be in good agreement within .+-.5% when compared with the previous numerical and exact solutions, respectively. The thermal stress intensity factors for symmetric lip and airfoil cusp cracks in finite bodies are calculated about various effective crack lengths, configuration parameters, and heat flow directions. With the same crack surface thermal boundary conditions, heat flow directions and crack lengths, there are no appreciable differences in variations of thermal stress intensity factors between symmetric lip and airfoil cusp cracks. The signs of thermal stress intensity factors for each cusp crack are changed with each crack surface thermal boundary condition.

Boundary Element Analysis of Thermal Stress Intensity Factors for Cusp Crack in Transient State (천이상태에 있는 커스프균열에 대한 열응력세기계수의 경계요소 해석)

  • 이강용;홍정균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.9
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    • pp.1700-1710
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    • 1992
  • The boundary element method is applied to determine thermal stress intensity factors for a cusp crack in transient state. In the steady temperature field, numerical values of thermal stress intensity factors for a Grifith crack and a symmetric lip cusp crack in a finite body are in good agreement within .+-. 5% with the previous solutions. In transient state, the numerical values of thermal stress intensity factors for the Griffith crack are also in good agreement with the pervious solutions. In both steady and transient states, those for the symmetric lip cusp crack with the crack surface insulated or fixed to the constant temperature are calculates for various effective crack lengths, configuration parameters and uniform heat flow angles. The variations of the thermal boundary conditions of the crack surface have a effect on stress intensity factors. The signs on the values of thermal stress intensity factors can be changed in time variation.

Stress intensity factor and stress distribution near crack tip for infinite body containing regid inclusion with crack shape (균열형상의 강체함유물을 포함하는 무한체에 대한 균열선단 부근의 응력분포와 응력세기계수)

  • Lee, Kang-Young;Kim, Jong-Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.3
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    • pp.680-683
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    • 1998
  • In case of the infinite body containing a rigid inclusion with line crack shape, stress intensity factor is determined and the relation between stress intensity factor and stress distribution near a crack tip is developed. Also, the relation between stress intensity factor and Kolosoff stress function is developed. Finally, these results are compared with those that the crack surface is under no traction.

Stress Intensity Factor for the Cracked Sheet Subjected to Normal Stress and Reinforced with a Plate by Spot Welding (점용접에 의하여 판재로 보강된 균열판의 수직응력에 의한 응력세기계수)

  • 이강용;김옥환
    • Journal of Welding and Joining
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    • v.15 no.1
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    • pp.55-65
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    • 1997
  • The stress intensity factor has been calculated for the cracked plate subjected to remote normal stress and reinforced with a plate by symmetric spot welding. The solution was based on displacement compatibility condition between the cracked sheet and the reinforcement plate. It is shown that the results from the derived equation for stress intensity factor were agreed with previous solutions. The reinforcement effect gets better as a joining spot is closer to the crack tip and the other joining spots become nearer to the crack surface.

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Boundary element analysis of stress intensity factors for the bimaterial interface cracks (접합재료 경계면 균열의 응력세기계수에 대한 경계요소해석)

  • 이강용;최형집
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.6
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    • pp.884-894
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    • 1987
  • Stress intensity factors for the bimaterial interface cracks are determined by the boundary element method employing the multiregion technique along with the double-point concept. For this purpose, the formulas relating the stress intensity factors to the crack surface displacements, which are applicable to both the homogeneous and the bimaterial systems, are derived and the accuracy of the results is discussed using the preexisting analytic solutions. Besides, the stress intensity factors for the edge-cracked bimaterial plates are computed with various crack lengths and shear modulus ratios under the biaxial and the uniaxial loadings, respectively, to demonstrate the dependence of stress intensity factors on the loading conditions and the material properties.