• Title/Summary/Keyword: stress intensity factor

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Boundary Element Analysis of Thermal Stress Intensity Factor for Interface Crack under Vertical Uniform Heat Flow (경계요소법을 이용한 수직열유동을 받는 접합경계면 커스프균열의 열응력세기계수 결정)

  • Lee, Kang-Yong;Baik, Woon-Cheon
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7 s.94
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    • pp.1794-1804
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    • 1993
  • The thermal stress intensity factors for interface cracks of Griffith and symmetric lip cusp types under vertical uniform heat flow in a finite body are calculated by boundary element method. The boundary conditions on the crack surfaces are insulated or fixed to constant temperature. The relationship between the stress intensity factors and the displacements on the nodal point of a crack tip element is derived. The numerical values of the thermal stress intensity factors for interface Griffith crack in an infinite body and for symmetric lip cusp crack in a finite and homogeneous body are compared with the previous solutions. The thermal stress intensity factors for symmetric lip cusp interface crack in a finite body are calculated with respect to various effective crack lengths, configuration parameters, material property ratios and the thermal boundary conditions on the crack surfaces. Under the same outer boundary conditions, there are no appreciable differences in the distribution of thermal stress intensity factors with respect to each material properties. But the effect of crack surface thermal boundary conditions on the thermal stress intensity factors is considerable.

Stress Effects on Activity of Primary Cracks Initiating at Stress Concentrator (응력 집중원에서 발생하는 초기 균열의 거동에 미치는 응력장의 영향)

  • Song, Sam-Hong;Kim, Jin-Bong
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.3 s.96
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    • pp.145-153
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    • 1999
  • This study has been performed to investigate the stress distribution around defects that behave as stress concentrators and fracture mechanical analysis for cracks initiatiating at stress concentrators. The stress distribution was analyzed using Finite Element Method and non dimensional stress intensity factor was determined by the mean stress method. In addition, stress interaction effects around defects and cracks were compared.

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A Photoelastic Study on the Stress Intensity Factor of Circular Disk with an Are-crack (광탄성법에 의한 원고형상크랙을 갖는 원판의 응력확대계수에 관한 연구)

  • Lee, Chi-Woo;Kim, Tae-Gyu;Yang, Jang-Hong;O, Se-Uk
    • Journal of Ocean Engineering and Technology
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    • v.2 no.2
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    • pp.96-103
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    • 1988
  • The stress distribution in the vicinity of the crack tip in the fracture mechanics is ordenarily indicated by the stress intensity factor. In the analysis of stress intensity factors, there are many theoretical and experimental methods. The stress analysis in photoelastic technique is usually made by using the difference of the principal stress of isochromatic fringe patterns. In this paper, the teflon molding technique is adopted to make a test specimen with a circular arc-crack, and that upgraded the accuracy of experiment. As the result, the experimental values of the stress intensity factors for the circular disk with a straight crack are coincided with the theoretical values. But, there is quite a difference between this expermental results on the finite plate for circular arc-crack and its theoretical values on the infinite one. Therefore, a boundary condition with regard to the loading condition on finite disk must be considered.

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Stress intensity factor in cracked plate reinforced with a plate under mixed mode loading (혼합형 하중항에 있는 판재로 보강된 균열판의 응력세기계수)

  • Lee, Kang-Yong;Kim, Ok-Whan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.3
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    • pp.569-578
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    • 1998
  • The mode I and II stress intensity factors have been calculated theoretically for the cracked plate reinforced with a plate by symmetric spot welding under remote mixed mode loading. This is the extension of authors' previous work for the reinforced cracked plate under remote normal stress. Regardless of loading types, the reinforcement effect gets better as one joining spot is closer to the crack tip and the others are closer to the crack surface, and optimum number of the joining spots can be existed. For the present model, the remote loading parallel to crack surface produces the mode I stress intensity factor.

Study on fracture mechanics of granite specimens with different precast notch depths based on DIC method

  • Shuwen Cao;Hao Shu
    • Geomechanics and Engineering
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    • v.33 no.4
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    • pp.393-400
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    • 2023
  • Displacements near crack and stress intensity factor (SIF) are key parameters to solve rock failure issue when using fracture mechanics. In order to study the horizontal displacement and stress intensity factor of the mode I fracture, a series of three-point bending tests of granite specimens with central notch were carried out. The evolution of horizontal displacements of precast notch and crack tip opening displacements (CTOD) were analyzed based on the digital image correlation (DIC) method. Stress intensity factors for three-point bending beams with arbitrary span-to-width ratios(S/W) were calculated by using the WU-Carlsson analytical weight function for edge-crack finite width plate and the analytical solution of un-cracked stress by Filon. The present study provides a high efficient and accurate method for fracture mechanics analysis of the three-point bending granite beams.

Weight Function Theory for Piezoelectric Materials with a Crack (균열을 가진 압전재료에서의 가중함수이론)

  • 손인호;안득만
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.7
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    • pp.208-216
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    • 2003
  • In this paper, a two-dimensional electroelastic analysis is performed on a piezoelectric material with an open crack. The approach of Lekhnitskii's complex potential functions is used in the derivation and Bueckner's weight function theory is extended to piezoelectric materials. The stress intensity factors and the electric displacement intensity factor are calculated by the weight function theory.

Weight Function Theory for Piezoelectric Materials with Crack in Anti-Plane Deformation (균열을 가진 압전재료에 대한 면외 변형에서의 가중함수이론)

  • Son, In-Ho;An, Deuk-Man
    • Journal of Ocean Engineering and Technology
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    • v.24 no.3
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    • pp.59-63
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    • 2010
  • In this paper, an electroelastic analysis is performed on a piezoelectric material with an open crack in anti-plane deformation. Bueckner’s weight function theory is extended to piezoelectric materials in anti-plane deformation. The stress intensity factors and electric displacement intensity factor are calculated by the weight function theory.

Analysis of Crack Growth in the Stiffened Panels by using Finite Element Method (유한요소법을 이용한 보강판의 균열거동해석)

  • 이환우;전원석
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.4
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    • pp.197-202
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    • 2000
  • A simple numerical procedure is presented to determine the stress intensity factors for crack in a stiffened panel subjected to a uniaxial uniform stress normal to the crack. Two types of stiffened panels are analyzed by the finite element method for various values of crack lengths, stiffness ratios, and stiffener spacings. From the finite element solution, the stress intensity factors were determined by using hybrid extrapolation method. Results are presented in graphical forms for upper mentioned parameters.

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Study on the Stress Singularity of Interface Crack by using Boundary Element Method (경계요소법을 이용한 계면균열의 응력특이성에 관한 고찰)

  • Cho, Chong-Du;Kwahk, Si-Young
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.4 s.97
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    • pp.197-204
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    • 1999
  • The boundary element method was used for studying singularities of an interface crack with contact zones. The iterative procedure is applied to estimate the contact zone size. Because the contact zone size was extremely small in a tension field, a large number of Gaussian points were used for numerical integration of the Kernels. Stress extrapolation method and J-integral were used ofr determining stress intensity factors. When the interface crack was assumed to have opened tips, oscillatory singularities appear near the tips of the interface crack. But the interface crack with contact zone which Comninou suggested had no oscillatory behavior. The contact zone size under shear loading was much larger than that under tensile. The stress intensity factors computed by stress extrapolation method were close to those of Comninou's solution. And the stress intensity factor evaluated by J-integral was similar to that by stress extrapolation method.

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EFFECTS OF INTERFACE CRACKS EMANATING FROM A CIRCULAR HOLE ON STRESS INTENSITY FACTORS IN BONDED DISSIMILAR MATERIALS

  • CHUNG N.-Y.;SONG C.-H
    • International Journal of Automotive Technology
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    • v.6 no.3
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    • pp.293-303
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    • 2005
  • Bonded dissimilar materials are being increasingly used in automobiles, aircraft, rolling stocks, electronic devices and engineering structures. Bonded dissimilar materials have several material advantages over homogeneous materials such as high strength, high reliability, light weight and vibration reduction. Due to their increased use it is necessary to understand how these materials behave under stress conditions. One important area is the analysis of the stress intensity factors for interface cracks emanating from circular holes in bonded dissimilar materials. In this study, the bonded scarf joint is selected for analysis using a model which has comprehensive mixed-mode components. The stress intensity factors were determined by using the boundary element method (BEM) on the interface cracks. Variations of scarf angles and crack lengths emanating from a centered circular hole and an edged semicircular hole in the Al/Epoxy bonded scarf joints of dissimilar materials are computed. From these results, the stress intensity factor calculations are verified. In addition, the relationship between scarf angle variation and the effect by crack length and holes are discussed.