• Title/Summary/Keyword: stress intensity factor

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Stress Intensity Factor for the Cracked Plate Reinforce with a Plate by Seam Welding

  • Kim, O.W.;Park, S.D.;Lee, Y.H.
    • International Journal of Korean Welding Society
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    • v.1 no.2
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    • pp.18-22
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    • 2001
  • The stress intensity factor has been calculated theoretically for the cracked plate subjected to remote normal stress and reinforced with a plate by symmetric seam welding. The singular integral equation was derived based on displacement compatibility condition between the cracked plate and the reinforcement plate, and solved by means of Erdogan and Gupta's method. The results from the derived equation for stress intensity factor were compared with FEM solutions and seems to be reasonable. The reinforcement effect gets better as welding line is closer to the crack and the stiffness ratio of the cracked plate and the reinforcement plate becomes larger.

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Mode III Dynamic Interfacial Crack in Bonded Anisotropic Strip Under Anti-Plane Deformation (이방성재료 접합 띠판에 대한 면외 동적계면균열)

  • Park, Jae-Wan;Choi, Sung-Ryul
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.111-116
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    • 2000
  • A semi-infinite interfacial crack propagated with constant velocity in two bonded anisotropic strip under out-of-plane clamped displacements is analyzed. The asymptotic stress and displacement fields near the crack tip are obtained, where the results get more general expressions applicable not only to isotropic/orthotropic materials but also to the extent of the anisotropic material having one plane of elastic symmetry for the interfacial crack. The dynamic stress intensity factor is obtained as a closed form, which is decreased as the velocity of crack propagation increases. The critical velocity where the stress intensity factor comes to zero is obtained, which agrees with the lower value between the critical values of parallel crack merged in the material 1 and 2 adjacent to the interface. The dynamic energy release rate is also obtained as a form related to the stress intensity factor.

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Analysis of Stress Intensity Factor for the Cracked Plate Reinforced with a Sheet by Seam Welding (심용접에 의한 판재로 보강된 균열판의 응력세기계수 해석)

  • 김옥환;박성두;이영호
    • Journal of Welding and Joining
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    • v.16 no.1
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    • pp.63-69
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    • 1998
  • The stress intensity factor has been calculated theoretically for the cracked plate subjected to remote normal stress and reinforced with a sheet by symmetric seam welding. The singular integral equation was derived based on displacement compatibility condition between the cracked sheet and the reinforcement plate, and solved by means of Erdogran and Gupta's method. The results from the derived equation for stress intensity factor were compared with FEM solutions and seems to be reasonable. The reinforcement effect gets better as welding line is closer to the crack and the stiffness ratio of the cracked plate and the reinforcement sheet becomes larger.

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Determination of S.I.F. for Mixed Mode Crack and Development of Accuracy (혼합모드 균열의 응력확대계수 해석과 정도 개선에 대한 고찰)

  • Bae, Won-Ho
    • Journal of the Korean Society of Industry Convergence
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    • v.7 no.4
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    • pp.355-361
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    • 2004
  • The finite element method were used to determine the stress intensity factor of cracked plate. The stress method, displacement method and J Integral are most popular finte element method. ANSYS proposed another a kind of displacement method. In this paper, it was examined that the accuracy and utility of the ANSYS method could believable to determine the stress intensity factors of centered inclined crack. Generally, inclined crack has two portion of stress intensity factors, tensile mode F1 and shear mode F2. For the purpose of increasing the accuracy of stress intensity factors, examined the effect of the numbers of nodes and elements, crack tip element size and number of partition of the crack tip vicinity. It was found that the method proposed by ANSYS is useful and has high accuracy. Accuracy of calculated stress intensity factors was increased by increase of the number of nodes and elements, and at the small size of crack tip elements can get more highly accuracy.

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SIF AND FINITE ELEMENT SOLUTIONS FOR CORNER SINGULARITIES

  • Woo, Gyungsoo;Kim, Seokchan
    • East Asian mathematical journal
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    • v.34 no.5
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    • pp.623-632
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    • 2018
  • In [7, 8] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities. They consider the Poisson equations with homogeneous boundary conditions, compute the finite element solutions using standard FEM and use the extraction formula to compute the stress intensity factor(s), then they posed new PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor(s), which converges with optimal speed. From the solution they could get an accurate solution just by adding the singular part. Their algorithm involves an iteration and the iteration number depends on the acuracy of stress intensity factors, which is usually obtained by extraction formula which use the finite element solutions computed by standard Finite Element Method. In this paper we investigate the dependence of the iteration number on the convergence of stress intensity factors and give a way to reduce the iteration number, together with some numerical experiments.

Determination of Compound Stress Intensity Factor by Superposition Method (중첩법에 의한 복합응력확대계수의 결정)

  • 조재웅;한문식
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.11
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    • pp.244-250
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    • 1998
  • In this study, the stress intensity factors of center crack are analyzed when it is surrounded by symmetrically distributed small cracks. The values of stress intensity factors of the center crack are greatly influenced by the locations of distributed small cracks. When small cracks overlap or approach near the tip of a center crack, the effect of interaction arisen by these cracks becomes noticeable. In case of multiple distributed small cracks, the stress intensity factor of a center crack is found to be efficiently determined by the superposition method.

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The Effect of Fatigue Fracture in shot peening Marine structural steel at stress ratio (쇼트피닝 가공된 해양구조용강의 피로파괴에 미치는 응력비의 영향)

  • Park, Kyoung-Dong;Han, Kun-Mo;Jin, Young-Beom
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.138-144
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    • 2003
  • Rencentely, the request for the light weight is more incresed in the area of industrial environment and machinery and consistent effort is needed to accomplish high strength of material for the direction of light weight. we got the following characteristic from crack growth test carried out in the range of stress ration of 0.1, 0.3 and 0.6 by means of opening mode displacement. At the content stress ratio, the threshold stress intensity factor crack range ${\Delta}K_{th}$in the early stage of fatigue crack growth (Region I) and dtress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) with an increase in ${\Delta}K$. Fatigue life shows more improvement in the Shot-peened material than in the Un-peening material. And compressive residual stress of surface on the Shot peening processed operate resistance force of fatigue. So we can obtain fallowings. (1) The fatigue crack growth rate on stage II is conspicuous with the size of compressive residual stress and is depend on Paris equation. (2) Although the maxium compressive residual stress is deeply and widely formed from surface, fatigue life does not improve than when maxium compressive residual stress is formed in surface. (3) The threshold stress intensity factor range is increased with increasing compressive residual stress.

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A study on the calculation of stress intensity factor for a patched crack using approximate weight function (근사적 가중함수를 이용한 보강된 균열평판의 응력강도계수 계산에 대한 연구)

  • Kim, Jong-Ho;Lee, Soon-Bok
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.123-128
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    • 2000
  • A cracked-plate with a patch bonded on one side is treated with a crack-bridging model: assuming continuous distribution of springs acting between crack surfaces. the approximate weight function was introduced to obtain the stress intensity factor of patched crack subjected to residual stress or non-uniform stress. The stress intensity factors for the partially patched crack within finite plate or the patched crack initiated from a notch were successfully obtained by numerical calculation.

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An Evaluation Method of Fracture Toughness on Interface Crack in Friction Welded Dissimilar Materials (이종 마찰용접재의 계면균열에 대한 파괴인성의 평가방법)

  • Chung, Nam-Yong;Park, Cheol-Hee
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.4
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    • pp.171-177
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    • 2007
  • In this paper, an evaluation method of fracture toughness on interface cracks was investigated in friction welded dissimilar materials with interfacial edge cracks. To establish a reasonable strength evaluation method and fracture criterion, it is necessary to analyze stress intensity factor under the load and residual stress condition on friction welded interface between dissimilar materials. The friction welded specimens with an edged crack were prepared for analysis of stress intensity by using the boundary element method (BEM) and the fracture toughness. A quantitative fracture criterion for friction welded STS 304/SM 45C with interface crack is suggested by using stress intensity factor, F and the results of fracture toughness experiment.

Determination of Stress Intensity Factors for Embedded Elliptical Crack in Turbine Rotor (터빈축차내에 내재된 타원균열의 응력세기계수 결정)

  • 이강용;김종성;하정수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.5
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    • pp.1229-1242
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    • 1995
  • The thermal shock stress intensity factors of semi-elliptical surface crack in finite plate and the stress intensity fractors of embedded elliptical crack in turbine rotor is determined by means of Vainshtok weight function method. In case of semi-elliptical surface crack, the solution is compared with previous solution. The stress intensity factor for embedded elliptical crack in turbine rotor loaded by centrifugal and thermal loading is also determined. In this case, the value of stress intensity factor is larger at crack contour near internal radius surface and is almost constant at the crack contour farther from internal radius surface.