• Title/Summary/Keyword: fracture propagation path

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Influence of size and location of a pre-existing fracture on hydraulic fracture propagation path

  • Bo, Zhang;Yao, Li;Xue Y., Yang;Shu C., Li;Chao, Wei;Juan, Songa
    • Geomechanics and Engineering
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    • v.32 no.3
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    • pp.321-333
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    • 2023
  • Rock masses often contain natural fractures of varying sizes, and the size of the natural fractures may affect the propagation of hydraulic fractures. We conduct a series of triaxial hydraulic fracturing tests to investigate the effect of the pre-existing fracture size a on hydraulic fracture propagation. Experimental results show that the pre-existing fracture size impacts hydraulic fracture propagation. As the pre-existing fracture size increases, the hydraulic fracture propagates towards the pre-existing fracture tips, evidenced by the decreased distance between the final hydraulic fracture and the pre-existing fracture tips. Furthermore, the attracting effect of pre-existing fracture tips increases when the distance between the wellbore and the pre-existing fracture is short (L/D=2 or 4 in this study). With increased distance between the wellbore and the pre-existing fracture (L/D=6 in this study), the hydraulic fracture propagates to the middle of the pre-existing fracture rather than the tips, as the attracting effect of the pre-existing fracture diminishes.

Prediction of Propagation Path for the Interface Crack in Bonded Dissimilar Materials (이종접합재의 계면균열에 대한 진전경로의 예측)

  • 정남용;송춘호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.3
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    • pp.112-121
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    • 1996
  • Applications of bonded dissimilar materials such as metal/ceramics and resin/metal joints, are very increasing in various industry fields. It is required to find crack propagation direction and path applying to the fracture mechanics on the bonded joint of dissimilar meterials. In this paper, crack propagation direction and path were simulated numerically by using boundary element method. Crack propagation angle is able to easily determine based on the maximum stress concept. Fracture tests of Al/Epoxy dissimilar materials with an interface crack are carried out under various mixed mode conditions by using the specimens of bonded scarf joints. It is found that the experimental results are well coincide with the analysis results of boundary element method.

A boundary element approach for quasibrittle fracture propagation analysis

  • Tin-Loi, F.
    • Structural Engineering and Mechanics
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    • v.8 no.5
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    • pp.439-452
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    • 1999
  • A simple numerical scheme suitable for tracing the fracture propagation path for structures idealized by means of Hillerborg's classical cohesive crack model is presented. A direct collocation, multidomain boundary element method is adopted for the required space discretization. The algorithm proposed is necessarily iterative in nature since the crack itinerary is a priori unknown. The fracture process is assumed to be governed by a path-dependent generally nonlinear softening law. The potentialities of the method are illustrated through two examples.

Analyses of Fracture Parameters and Prediction of Crack Propagation Path on Delamination in the LSI Package (반도체 패키지의 층간박리 파괴역학인자 해석 및 균열진전경로 예측)

  • Chung, Nam-Yong;Park, Cheol-Hee
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.4
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    • pp.401-409
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    • 2009
  • This paper presents a method of calculating the stress intensity factor (K) and crack propagation direction (${\theta}_0$) at the crack-tip that is associated with delamination in the large scale integration(LSI) package. To establish a reasonable strength evaluation method and life prediction, it is necessary to assess fracture parameters under various fracture conditions. Therefore, we conducted quantitative stress singularity analysis considering thermal stress simulating the changes of crack length (a), (h) and (v) in delamination using the 2-dimensional elastic boundary element method (BEM), and from these results predicted crack propagation direction and path.

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Fracture Characteristics and Stress Analysis of $Si_3N_4/SM45C$ Joint ($Si_3N_4/SM45C$ 접합부의 응력해석 및 파괴특성)

  • 김기성
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1998.10a
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    • pp.248-253
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    • 1998
  • Recently, the uses of Ceramic/metal bonded joints, resin/metal joints, adhesive joints, composite materials which are composed of dissimiliar materials have increased in various industry fields. Since the ceramic/metal bonded joints material is made at a high temperature, residual stress distributions due to differences in material properties were investigated by varying material parameters. The two dimensional finite element analysis was performed to study residual stress distribution in Si3N4/SM45C bonded joint with a copper interlayer between the silicon nitride(Si3N4) and the structural carbon steel(SM45C) and 4-point bending tests were carried out under room temperature. Fracture surface and crack propagation path were observed using scanning electron microscope and characteristics of its fracture was discussed.

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Fracture Behaviors of Alumina Tubes under Combined Tension/Torsion (알루미나 튜브의 인장/비틀림 조합하중하의 파괴거동)

  • Kim, K.T.;Suh, J.;Cho, Y.H.
    • Journal of the Korean Ceramic Society
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    • v.28 no.1
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    • pp.20-28
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    • 1991
  • Fracture of Al2O3 tubes for different loading path under combined tension/torsion was investigated. Macroscopic directions of crack propagation agreed well with the maximum principal stress criterion, independent of the loading path. However, fracture strength from the proportional loading test($\tau$/$\sigma$= constant) showed either strengthening or weakening compared to that from uniaxial tension, depending on the ratio $\tau$/$\sigma$. The Weibull theory was capable to predict the strengthening of fracture strength in pure torsion, but not the weakening in the proportional loading condition. The strengthening or weakening of fracture strength in the proportional loading condition was explained by the effect of shear stresses in the plane of randomly oriented microdefects. Finally, a new empirical fracture criterion was proposed. This criterion is based on a mixed mode fracture criterion and experimental data for fracture of Al2O3 tubes under combined tension/torsion. The proposed fracture criterion agreed well with experimental data for both macroscopic directions of crack propagation and fracture strengths.

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Analysis of Fracture Mechanics Parameter and Fracture Surface in Bonded Ceramic Joints (세라믹 접합부재에 대한 파괴역학인자 및 파면 해석)

  • 김기성
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1997.04a
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    • pp.156-163
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    • 1997
  • Recently, attempts have been made to be join ceramics to metals in order to make up for the brittleness of ceramics. The difference in the coefficients of linear expansion of the two materials joined at high temperature will cause residual stress, which has a strong influence on the strength of the bonded joints. In this paper, the residual stress distribution and stress intensity factors of the ceramic/metal bonded joints were analyzed by 2-dimensional elastic boundary element method. Fracture toughness tests of ceramic/metal bonded joints with an interface crack were carried out. So the advanced method of quantitative strength evaluation for ceramic/metal bonded joints is to be suggested. Fracture surface and crack propagation path were observed using scanning electron microscope.

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Fatigue Crack Growth Behavior of Gray Cast Iron for Brake Disc of a Passenger Car (대형승용차 디스크 브레이크용 회주철의 피로균열 전파 거동)

  • Kim, Ho-Kyung;Park, Jin-Ho;Yang, Kyoung-Tak;Choi, Deok-Ho
    • Journal of the Korean Society of Safety
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    • v.21 no.4 s.76
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    • pp.19-24
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    • 2006
  • Fatigue crack propagation tests for the brake disc cast iron were conducted for investigating fatigue crack propagation rate(da/dN), crack propagation path and fracture toughness($K_c$) of the material. The threshold stress intensity factor range, ${\Delta}K_{th}$, was found to be about $6MPa{\sqrt{m}}$ at the stress ratio of R = 0.1. Also, fracture toughness value was determined to be $24.7MPa{\sqrt{m}}$. Irregular fatigue fracture surfaces were observed, indicating that fatigue crack growth occurred at the interface between randomly scattered flak graphite and ferrite, where the interfacial strength was relatively weak.

Prediction of crack propagation path in IC package by BEM (경계요소법에 의한 반도체 패키지의 균열진전경로 예측)

  • Song, Chun-Ho;Chung, Nam-Yong
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.286-291
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    • 2001
  • Applications of bonded dissimilar materials such as IC package, ceramic/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edges in bonded joints of dissimilar materials. In orer to understand the package crack emanating from the edge of Die pad and Resin, fracture mechanics of bonded dissimilar materials and material properties are obtained. In this paper, the thermal stress and its singularity index for the IC package were analyzed using 2-dimensional elastic boundary element method. Crack propagation angle and path by thermal stress were numerically simulated with boundary element method.

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Prediction of Crack Propagation Path Using Boundary Element Method in IC Packages (반도체 패키지의 경계요소법에 의한 균열진전경로의 예측)

  • Chung, Nam-Yong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.3
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    • pp.15-22
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    • 2008
  • Applications of bonded dissimilar materials such as integrated circuit(IC) packages, ceramics/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edge in bonded joints of dissimilar materials. In order to investigate the IC package crack propagating from the edge of die pad and resin, the fracture parameters of bonded dissimilar materials and material properties are obtained. In this paper, the thermal stress and its singularity index for the IC package were analyzed using 2-dimensional elastic boundary element method(BEM). From these results, crack propagation direction and path by thermal stress in the IC package were numerically simulated with boundary element method.