• Title/Summary/Keyword: interface crack

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Analysis of Propagating Crack Along Interface of Isotropic-Orthotropic Bimaterial by Photoelastic Experiment

  • Lee, K.H.;Shukla, A.;Parameswaran, V.;Chalivendra, V.;Hawong, J.S.
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.102-107
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    • 2001
  • Interfacial cracks between an isotropic and orthotropic material, subjected to static far field tensile loading are analyzed using the technique of photoelasticity. The fracture parameters are extracted from the full-field isochromatic data and the same are compared with that obtained using boundary collocation method. Dynamic Photoelasticity combined with high-speed digital photography is employed for capturing the isochromatics in the case of propagating interfacial cracks. The normalized stress intensity factors for static crack is greater when $\alpha=90^{\circ}C$ (fibers perpendicular to the interface) than when $\alpha=0^{\circ}C$ (fiber parallel to the interface) and those when $\alpha=90^{\circ}C$ are similar to ones of isotropic material. The dynamic stress intensity factors for interfacial propagating crack are greater when $\alpha=0^{\circ}C$ than $\alpha=90^{\circ}C$. The relationship between complex dynamic stress intensity factor $|K_D|$ and crack speed C is similar to that for isotropic homogeneous materials, the rate of increase of energy release rate G or $|K_D|$ with crack speed is not as drastic as that reported for homogeneous materials.

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Analysis of Crack Behavior of dissimilar materials in Brazed Interface By BEM (이종재 브레이징 계면에서의 균열거동해석)

  • 오환섭;김시현;김성재
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.10a
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    • pp.269-274
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    • 2001
  • Applications of Brazing in the studying fields such as High-Speed Machining are very increasing in various industry fields. Therefore, Applying to the fracture mechanics by numerical analysis method is very important to analyse the crack problem Dissimilar Materials in Brazed Interface. In this study, Stress intensity Factor (S.I.F) is analysed to investigate crack behavior on the crack tip of dissimilar materials in brazed interface such as a Hardmetal and a HSS by two dimensional(2-D) Boundary Element Method (BEM). Kelvin's solution was used as a fundamental solution in BEM analysis and stress extrapolation method was used to determine Stress Intensity Factor.

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Boundary Element Evaluation of Stress Intensity Factor for Interface Crack in Elastic and Viscoelastic Composite Materials (경계요소법에 의한 탄성-점탄성 복합구조체의 계면균열 해석)

  • 이상순;김정규;황종근
    • Computational Structural Engineering
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    • v.9 no.1
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    • pp.85-91
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    • 1996
  • The focus of the present work is on the computation of the stress intensity factor for the crack at the elastic-viscoelastic bimaterial interface. First, the stress intensity factor for an interface crack in dissimilar elastic and viscoelastic materials is dervied by applying the correspondence principle to associated elastic expression. Then the time-domain boundary element analysis is performed to calculate the stress intensity factor. Numerical results show that the proposed method is very useful for the analysis of the interface crack in elastic and viscoelastic materials.

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Detection of Interface Crack Using Ultrasonic Method in Adhesively Bonded Joints (초음파 탐상법을 이용한 접착이음에 대한 계면 균열의 검출)

  • Jeong, Nam-Yong;Park, Seong-Il;Lee, Myeong-Dae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.3
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    • pp.415-423
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    • 2001
  • In is well recognized that the ultrasonic method is one of the most common and reliable nondestructive testing(NDT) methods for the quantitative estimation of defects in welded structures. However, NDT techniques applying for adhesively bonded joints have not been clearly established yet. In this paper, the detection of interface crack by the ultrasonic method was applied for the measurement of interface crack length in the adhesively bonded joints of double-cantilever beam(DCB). The optimum condition of transmission coefficients and experimental accuracy by the ultrasonic method in the adhesively bonded joints have been investigated. The experimental values are in good agreement with the computed results by boundary element method(BEM) and Riplings equation.

Evaluation of Ct-parameter for Weld Interface Crack Considering Material Plastic Behavior (재료의 소성 거동을 고려한 용접 계면균열의 Ct 매개변수)

  • Yun, Gi-Bong;Lee, Jin-Sang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.3 s.174
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    • pp.676-684
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    • 2000
  • In this study, behavior of $C_t$ which is a well-known fracture parameter characterizing creep crack growth rate, is investigated for weld interface cracks. Finite element analyses were per formed for a C(T) specimen under constant loading condition for elastic-plastic-creeping materials. In modeling C(T) geometry, an interface was employed along the crack plane which simulated the interface between weld and base metals. The $C_t$ versus time relations were obtained under various creep constant combinations and plastic constant combinations for weld and base metals, respectively. A unified $C_t$ versus time curve is obtained by normalizing $C_t$ with $C^*$ and t with $t_T$ for all the cases of material constant variations.

Establishment of fracture Criterion for Mixed Mode in Bonded Dissimilar Materials (이종 접합체에 대한 혼합모드 파기기준의 설정)

  • 정남용
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1998.10a
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    • pp.254-260
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    • 1998
  • Application of bonded dissimilar materials in various industries are increasing. When these materials are used in structures, it needs to investigate strength evolution applying fracture mechanics. Al/Epoxy bonded dissimilar materials with an interface crack and an interface crack emanating from an edge semicircular hole were prepared for the static tests so that experiment of fracture toughness were carried out. Stress intensity factors of interface cracks in bonded dissimilar materials were computed with boundary element method(BEM) and the fracture criterion of mixed mode crack were analyzed. From the results, the fracture criterion and the method of strength evolution by the fracture toughness in Al/Epoxy bonded dissimilar materials were proposed.

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Analysis of Crack Behavior of Brazed Interface in Dissimilar Materials using BEM (이종재 브레이징 계면에서의 균열거동 해석)

  • 오환섭;김시현;김성재;양인수
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.6
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    • pp.91-97
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    • 2002
  • Applications of brazing in the studying fields such as high-speed machining are very increasing in various industry fields. Therefore, applying to the fracture mechanics by numerical analysis method is very important to analyse the crack problem dissimilar materials in brazed interface. In this study, stress intensity factor(SIF) is analysed to investigate crack behavior on the crack tip of dissimilar materials in brazed interface such as a hardmetal and a HSS by two dimensional(2-D) BEM. Kelvin's solution was used as a fundamental solution in BEM analysis and stress extrapolation method was used to determine SIF.

Determination of Thermal Dtress Intensity Factors for the Interface Crack under Vertical Uniform Heat Flow (수직 균일 열유동하에 있는 접합 경계면 균열의 열응력세기계수 결정)

  • 이강용;설창원
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.1
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    • pp.201-208
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    • 1991
  • In case that an interface crack exists in an infinite two-dimensional elastic bimaterial, the crack surface is insulated under traction free and the uniform heat flow vertical to the crack from infinite boundary is given. Temperature and stress potentials are obtained by using complex variable approach to solve Hilbert problems. The results are used to obtain thermal stress intensity factors. Only mode I thermal stress intensity factor occurs in case of the homogeneous material. Otherwise, mode I and II thermal stress intensity factor is much smaller than one of mode II.

Anaysis of the Interfacial Stress Intensity Factors and Fatigue Crack Growth Behaviour for the Edge Interface Crack in the Dissimilar Materials (이종재료 접합재의 편측접합계면균열의 응력확대계수 해석 및 피로균열성장 해석)

  • 이갑래;최용식
    • Journal of the Korean Society of Safety
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    • v.6 no.2
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    • pp.5-13
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    • 1991
  • In this paper, the interfacial stress intensity factors( $K_{i}$$K_1$+i $K_2$) for the edge interface crack in the dissimilar materials(isotropic-isotropic materials, isotropic-composite materials) were analysed by BEM(Boundary Element Method). The fatigue crack growth behaviour was investigated by load constant fatigue test. From the experimental results, the relationship between da/dN and interfacial stress intensity facto, ( $K_{i}$ or $K_1$) can be expressed by Paris'law for homogeneous materials.s.s.

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Application of L Integral to Interface Crack Problems (계면균열 문제에 대한 L적분의 응용)

  • 박재학;엄윤용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.1
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    • pp.34-42
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    • 1986
  • An interface of a circular arc formed by two isotropic, homogeneous elastic materials is investigated. It is shown that L integral satisfies the conservation law for the interface if it is perfectly bonded, in frictionless contact or separated such as in a crack with the origin of the coordinate system being located at the center of the circular arc. The property of path independence of the L integral is applied to an interfacial crack problem, to obtain the stress intensity factors, where the interfacial crack is located along the arc of the circular inclusion embedded in infinite matrix. It is assumed here that the contact zone exist as in the model proposed by Comninou, thus removing the overlapping of the materials along the interface. Another example is shown for case of a circular interfacial crack in the matrix of finite size, where the stress intensity factors are determined by computing a value of the L integral numerically along the path far from the crack tip.