• Title, Summary, Keyword: Bimaterial

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A Study on the Bimaterial Constant of Two Dissimillar Isotropic Bimaterial Under Static and Dynamic Load (정적 및 동적 하중을 받는 두 상이한 등방성 이종재료의 이종재료상수에 대한 연구)

  • Shin, Dong-Chul;Hawong, Jai-Sug
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1776-1785
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    • 2004
  • In this research, the relationships between static bimaterial constant and dynamic oscillation index are studied. It was certified that static bimaterial constant has the same form equation as the dynamic oscillation index. Bimaterial constant and oscillation index are increased with the increment of Young's modulus ratio and approached to the some value. Isochromatic fringe patterns are slanted to the left side with increment of bimaterial constants and oscillation index. Though patterns of stress components in above the crack surface are similar to each other, their magnitudes are different a little. In the ahead of crack tip, there are big differences in the isochromatic fringe patterns and their magnitudes. The influence of bimaterial with Young's modulus ratio is bigger in the propagation crack than in the stationary crack.

Determination of Stress Intensity Factors for Bimaterial Interface Rigid Line Inclusions by Boundary Element Method (경계요소법을 이용한 접합재료 경계면의 직선균열형상의 강체 함유물에 대한 응력세기계수 결정)

  • Lee, Kang-Yong;Kwak, Sung-Gyu
    • Proceedings of the KSME Conference
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    • pp.176-181
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    • 2000
  • Stress intensity factors for a rigid line inclusion tying along a bimaterial interface are calculated by the boundary element method with the multiregion and double-Point techniques. The formula between the stress intensity factors and the inclusion surface stresses are derived. The numerical values of the stress intensity factors for the bimaterial interface rigid line inclusion in the infinite body are proved to be in good agreement within 3% when compared with the previous exact solutions. In the finite bimaterial systems, the stress intensity factors for the center and edge rigid line inclusions at interface are computed with the variation of the rigid line inclusion length and the shear modulus ratio under the biaxial and uniaxial loading conditions.

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Dynamic Photoelastic Experimental Method for Propagating Interfacial Crack of Bimaterials (이종재료의 진전 계면 균열에 대한 동적 광탄성 실험법)

  • Shin, Dong-Chul;Hawong, Jai-Sug
    • Proceedings of the KSME Conference
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    • pp.292-297
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    • 2000
  • In this research, the dynamic photoelastic experimental hybrid method for bimaterial is introduced. Dynamic biaxial loading device is developed, its strain rate is 31.637 s-1 and its maximum impact load is 20 ton. Manufactured methods for model of the dynamic photoelastic experiment for bimaterial are suggested. They are bonding method(bonding material: AW106, PC-1) and molding method. In the bonding method, residual stress is not occurred in the manufactured bimaterial. Crack is propagated along the interface or sometimes deviated from the interface. While in the molding method, residual stress is occurred in the manufactured bimaterial. Crack is always deviated from the interface and propagated in the epoxy region(softer materila). In order to propagate with constant velocity along the interface of bimaterial with arbitrary stiffer material, edge crack should be located along the interface of the acute angle side of the softer material in the bimaterial.

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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.

Evaluation of stress intensity factor for a crack normal to bimaterial interface using cubic isoparametric finite elements (3차 등매개 유한요소를 이용한 이종재료 접합면에 수직인 균열의 응력확대계수 평가)

  • Lim, Won-Gyun;Jeong, Gyu-Cheol;Song, Chi-Hun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.206-214
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    • 1998
  • When a crack meets bimaterial interface stress singularity depends on the elastic constants of the adjacent materials. In the present study we are going to describe the finite element formulation for problems with a crack to be embedded in the stiffer material$({\mu}_2/{\mu}_1)$. The cubic isoparametric singular element, represented by adequately shifting the mid-side nodes adjacent to the crack tip is constructed to enclose the crack tip. An alternative method to obtain the optimal position of the mid-side nodes of cubic isoparametric elements is presented. In addition, a proper definition for the stress intensity factors of a crack normal to bimaterial interface is provided. It is based upon near a tip displacement solutions. Models for numerical analysis are two dimensional elastic bodies with a through crack under plain strain. The results obtained are compared with the previous solutions.

Estimation of Leak Rate Through Cracks in Bimaterial Pipes in Nuclear Power Plants

  • Park, Jai Hak;Lee, Jin Ho;Oh, Young-Jin
    • Nuclear Engineering and Technology
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    • v.48 no.5
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    • pp.1264-1272
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    • 2016
  • The accurate estimation of leak rate through cracks is crucial in applying the leak before break (LBB) concept to pipeline design in nuclear power plants. Because of its importance, several programs were developed based on the several proposed flow models, and used in nuclear power industries. As the flow models were developed for a homogeneous pipe material, however, some difficulties were encountered in estimating leak rates for bimaterial pipes. In this paper, a flow model is proposed to estimate leak rate in bimaterial pipes based on the modified Henry-Fauske flow model. In the new flow model, different crack morphology parameters can be considered in two parts of a flow path. In addition, based on the proposed flow model, a program was developed to estimate leak rate for a crack with linearly varying cross-sectional area. Using the program, leak rates were calculated for through-thickness cracks with constant or linearly varying cross-sectional areas in a bimaterial pipe. The leak rate results were then compared and discussed in comparison with the results for a homogeneous pipe. The effects of the crack morphology parameters and the variation in cross-sectional area on the leak rate were examined and discussed.

Fatigue Crack Growth Characteristics on The Weld Joint of Bimaterial (이종재료 용접부의 피로균열진전 특성)

  • 권재도;김우현;박중철;배용탁;김중형
    • Proceedings of the KWS Conference
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    • pp.81-85
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    • 1997
  • This paper was conducted the fatigue crack growth test on the base metal and weld joint of bimaterial(carbon-stainless steel), carbon steel and stainless steel. As the result, the fatigue crack growth rate of weld joint on the stainless-stainless steel is faster than stainless base metal, and weld joint on the carbon-carbon steel heat affected zone is slower than carbon base metal. And fatigue crack growth rate of carbon-stainless steel weld joint and heat affected zone is similar to the behavior of stainless base metal. In conclusion, weld joint of bimaterial is stable in the fatigue crack growth behavior.

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Determination of Interfacial Fracture Toughness by Bimaterial Eccentric Compression Test (이질재 편심압축실험에 의한 계면 파괴 인성치 산정)

  • 김형균;홍창우;양성철;윤경구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.78-81
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    • 2000
  • The test specimen proposed in this study, named the bimaterial eccentric compression specimen, is a rectangular prism of two dissimilar materials with a notch at their interface. Normalized energy release rates and phase angles were calibrated with the finite element method. The normalized energy release rate increases with notch ratio but decreases with E2/E2, loading point, and phase angle, Bimaterial specimens consisting of mortar and ploymer as well as mortar and rock were prepared and tested to simulate fracture behavior ar the interface. Test results have confirmed that initial notch has significant effect on the apparent interfacial toughness.

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A Study on the Near-Field Stresses and Displacement of a Stationary Interfacial Crack in Two Dissimilar Isotropic Bimaterials (두 상이한 등방성 이종재료 정지계면균열의 선단 응력장과 변위장에 관한 연구)

  • Shin, Dong-Chul;Hawong, Jai-Sug;Nam, Jeong-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.12
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    • pp.1897-1905
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    • 2004
  • In many part of machines or structures that made of bimaterial bonded with two dissimilar materials, most failures occur at their interface. Therefore, the accurate analysis of fracture characteristics and the evaluation of mechanical strength for interfacial crack are essential when we design those structures. In this research, stress and displacement components in the vicinity of stationary interfacial crack tip in the two dissimilar isotropic bimaterials are established. Hereafter, the stress components established in this research can be applied to the photoelastic hybrid method which can be used to analyze the fracture behavior of the two dissimilar isotropic bimaterials.

Variations of the stress intensity factors for a planar crack parallel to a bimaterial interface

  • Xu, Chunhui;Qin, Taiyan;Yuan, Li;Noda, Nao-Aki
    • Structural Engineering and Mechanics
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    • v.30 no.3
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    • pp.317-330
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    • 2008
  • Stress intensity factors for a planar crack parallel to a bimaterial interface are considered. The formulation leads to a system of hypersingular integral equations whose unknowns are three modes of crack opening displacements. In the numerical analysis, the unknown displacement discontinuities are approximated by the products of the fundamental density functions and polynomials. The numerical results show that the present method yields smooth variations of stress intensity factors along the crack front accurately. The mixed mode stress intensity factors are indicated in tables and figures with varying the shape of crack, distance from the interface, and elastic constants. It is found that the maximum stress intensity factors normalized by root area are always insensitive to the crack aspect ratio. They are given in a form of formula useful for engineering applications.