• Title/Summary/Keyword: singular stress field

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Singular Stress Field Analysis and Strength Evaluation in Ceramic/Metal Joints (세라믹/금속접합제의 응력특이장 해석 및 강도평가)

  • 박영철;한근조;허선철;강재욱
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.470-474
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    • 1997
  • Since the ceramic/metal joints is joined at high temperature, the residual stress will develop during when cooled from bonding temperature due to remarkable difference of thermal expansion coefficient between creamic and metal. Moreover, the edge of jointed interface makes singular stress field in the ceramic/metal joints and this singular stress field much influences on the strength of joints. In this study, The influence of residual stress, mechanical load and repeat thermal sysle was estimated in the ceramic/metal joints. According to this influence, the change of singular stress field was analyed and then strength test, X-ray measurement are performed.

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The intensity of a singular near-tip field around the vertex of a three-dimensional notch or wedge (3 차원 놋치 및 쐐기의 응력 강도계수)

  • Lee, Yong-Woo;Im, Se-Young
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.157-162
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    • 2003
  • Singular stress fields around three-dimensional wedges are examined, and the near-tip intensity is calculated via the two-state M-integral with the aid of the domain integral representation. A numerical example demonstrates the effectiveness and accuracy of the present scheme for computing the stress intensities of singular stresses near the generic three-dimensional wedges.

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Some Studies on Stress field in Dissimilar Materials

  • Katsuhiko Watanabe
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.631-635
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    • 1996
  • Stress singularities appear at the interface edge in dissimilar materials also under thermal loading. First, these singularities then an interface meets a free side surface with an arbitrary angle are studied for a two-dimensional problem. The singular properties under thermal loading are made clear and the concrete singular field are obtained. Secondly, the dependence of stress field on elastic constants in axisymmetric dissimilar materials are. discussed. That is, it is shown that three elastic constants mutually independent are necessary, in general, to characterize the stress field of axisymmetric dissimilar materials, although Dunders' parameters defined for two-dimensional dissimilar materials have been often applied correspondingly also to axisymmetric problems.

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Influence of elastic T-stress on the growth direction of two parallel cracks

  • Li, X.F.;Tang, B.Q.;Peng, X.L.;Huang, Y.
    • Structural Engineering and Mechanics
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    • v.34 no.3
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    • pp.377-390
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    • 2010
  • This paper studies fracture initiation direction of two parallel non-coplanar cracks of equal length. Using the dislocation pile-up modelling, singular integral equations for two parallel cracks subjected to mixed-mode loading are derived and the crack-tip field including singular and non-singular terms is obtained. The kinking angle is determined by using the maximum hoop stress criterion, or the ${\sigma}_{\theta}$-criterion. Results are presented for simple uniaxial tension and biaxial loading. The biaxiality ratio has a noticeable influence on crack growth direction. For the case of biaxial tension, when neglecting the T-stress the crack branching angle is overestimated for small crack inclination angles relative to the largest applied principal stress direction, and underestimated for large crack inclination angles.

입계기공의 확산성장 모델을 이용한 고온 기기의 크립균열전파 해석 (2)

  • Jeon, Jae-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.4
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    • pp.1186-1193
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    • 1996
  • The analytic solution of the stress field at creep crack in the presence of grain boundary caviation is to be obtained by solving the governing equation which was derived through the previous paper. The complex integral technique is used to slove the singular integral equation. under the help of the information about stress behaviors at the ends of integral region know by numerical solution. The resultant stress disstribution obtained shows the relaxed crack-tip singularity of $r^{1/2+\theta}$ due to the intervention of cavitation effect, otherwise, it should assumed to be $r^{1/2}$ singularity of linear elastic fracture mechanics with no cavitation.

Calculation of weight functions in single edge notched specimen (SEN시편에서의 무게함수 계산)

  • 안득만
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.604-610
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    • 1991
  • In this paper, the weight functions for the Mode I and Mode II in SEN(single edge notched) specimen are obtained by superposition of the displacement in the singular field of the Buckner type and the displacements by opposite tractions induced by the singular field. The stress intensity factors, $K_{I}$ and $K_{II}$ are calculated by the weight function theory in SEN specimen under the loading equivalent to uniform tension and shear at infinity in Griffith crack. And the results are compared with the exact solutions.s.

A Comparison of improved EFG method with the singular expression for crack tip (균열선단의 특이성을 반영한 개선된 EFG 해석기법들의 비교)

  • 이상호;윤영철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.69-76
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    • 2002
  • In this paper, several improved Element-Free Galerkin (EFG) methods containing singular expression in their approximation functions are compared one another through a patch test with near-tip field. Intrinsic enrichments that expand the basis function partially and fully with known near-tip displacement field and a local enrichment using auxiliary supports based on the partition of unity concept are examined by evaluating a relative stress norm error and the stress intensity factor. Some numerical examinations graphically show that how the size of compact support, dilation parameter and the diffraction parameter can affect the accuracy of the improved EFG methods in the error and the stress intensity factor.

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Analysis of Contact Singular Stresses with Relief Notch by Using Dynamic Photoelasticity(II) (동적 광탄성실험에 의한 응력이완 노치부근에서의 접촉특이응력 해석 (2))

  • Lee, Eok-Seop;Hwang, Si-Won;Nah, Gyeong-Chan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.7
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    • pp.2097-2107
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    • 1996
  • The dynamic photoelastic technique had been utilized to investigate the possibillity of relieving the large local singular stresses induced at the corner of a right- angle- indenter. The indenter compressed a semi-infinite body dynamically with an impact load applied on the top of the indenter. The effects of the geometric changes of the indenter in terms of the diameter (d) and the location (1) of the stress relieving notch on the behavior of the dynamic contact stresses were investigated. The influence of stress relieving notches positioned along the edge of the semi-infinite body on the dynamic contact stresses were also studied by changing the diameter (D) and the location (L) of the notch. A multi-speak-high speed camera with twelve sparks were used to take photographs of full field dynamic isochromatic fringe patterns. The contact singular stresses were found to be released significantly by the stress relief notches both along the indenter and the edge of the semi-infinite body. The optimal position and geometry of the stress relieving notches were obtained with the aid of limited experimental results.

The Crack Problem for Functionally Graded Piezoelectric Ceramic Strip (기능 경사 압전 세라믹 스트립의 균열에 관한 연구)

  • 신정우;김성찬
    • Composites Research
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    • v.15 no.4
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    • pp.37-42
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    • 2002
  • We consider the problem of determining the singular stresses and electric fields in a functionally graded piezoelectric ceramic strip containing a Griffith eccentric crack under anti-plane shear loading with the theory of linear piezoelectricity. Fourier transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. Numerical values on the stress intensity factor and the energy release rate are obtained.

Anti-Plane Shear Behavior of an Arbitrarily Oriented Crack in Bonded Materials with a Nonhomogeneous Interfacial Zone

  • Chung, Yong-Moon;Kim, Chul;Park, Hyung-Jip
    • Journal of Mechanical Science and Technology
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    • v.17 no.2
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    • pp.269-279
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    • 2003
  • The anti-plane shear problem of bonded elastic materials containing a crack at an arbitrary angle to the graded interfacial zone is investigated in this paper The interfacial zone is modeled as a nonhomogeneous interlayer of finite thickness with the continuously varying shear modulus between the two dissimilar, homogeneous half-planes. Formulation of the crack problem is based upon the use of the Fourier integral transform method and the coordinate transformations of basic field variables. The resulting Cauchy-type singular integral equation is solved numerically to provide the values of mode 111 stress intensity factors. A comprehensive parametric study is then presented of the influence of crack obliquity on the stress intensity factors for different crack size and locations and for different material combinations, in conjunction with the material nonhomogeneity within the graded interfacial zone.