• 제목/요약/키워드: Apparent fracture toughness

검색결과 22건 처리시간 0.024초

노치/균열 임계평균응력 파손모델을 이용한 임계노치반경 평가 (Evaluation of Critical Notch radius using Notch/Crack Critical Average Stress Fracture Model)

  • 김재훈;김덕회;김기수;안병욱
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1358-1361
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    • 2003
  • In this study, intrinsic static/dynamic fracture toughness of Al 7175-T74 are evaluated from the apparent static/dynamic toughness of notched specimen. The notch/crack critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The notch/crack critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, critical notch root radius can be predicted by notch/crack critical average stress fracture model.

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유효거리를 이용한 연소기관 노치부의 파손기준 해석 (Analysis of Failure Criterion for Combustion Pipe with Notch using Effective Distance)

  • 김덕회;김재훈;문순일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.1-6
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    • 2004
  • In this study, the intrinsic static/dynamic fracture toughness of Al 7175=T74 is evaluated from the apparent static/ dynamic toughness of notched specimen, The critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. Also, effective distance is applied to estimate the failure criterion for the combustion pipe with notch. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, the effective In this study, the intrinsic static/dynamic fracture toughness of Al 7175=T74 is evaluated from the apparent static/ dynamic toughness of notched specimen, The critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. Also, effective distance is applied to estimate the failure criterion for the combustion pipe with notch. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, the effective distance can be used to evaluate the failure criterion of structure with notch.

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Al 7175 합금의 정적 파괴인성에 미치는 노치반경 영향 (Notch Radius Effect for Static Fracture Toughness of Al 7175 Alloys)

  • 김재훈;김덕회;박성욱;문순일
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2002년도 제18회 학술발표대회 논문초록집
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    • pp.84-87
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    • 2002
  • In this study, intrinsic fracture toughness of Al 7175-T74 is evaluated from the apparent toughness of notched specimen. Modified average stress model is used to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched-cracked specimen. The modified average stress model is established the relation between notch radius and effective distance calculated by FEM analysis. The results show that fracture toughness decreases with decreasing of notch root radius. The true fracture toughness can be predicted from test results of apparent fracture toughness measured by using notched specimen.

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다양한 노치 반경을 갖는 17-4PH강의 동적균열개시 특성 (Dynamic Crack Initiation of 17-4PH Casting Steel for Various Notch Radius)

  • 박성욱;김덕회;김재훈;문순일
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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    • pp.160-163
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    • 2003
  • 본 논문에서는 17-4PH강의 동적파괴인성을 노치시편의 겉보기 동적파괴인성으로부터 평가하고자 한다. 0.1mm∼4mm의 다양한 노치반경을 갖는 시험편을 이용하였다. 임계노치반경 이상에서는 노치 반경이 증가할수록 겉보기 동적파괴인성도 증가하는 결과를 보인다. 노치시편을 이용하여 측정한 겉보기 동적파괴인성으로부터 동적파괴인성을 예측할 수 있다.

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J적분을 이용한 원자력 압력용기강의 파괴인성치의 결정 (A method of Determination of Fracture Toughness of Reactor Pressure Vessel Steel by J Integral)

  • 오세욱;임만배;김진선
    • 한국해양공학회지
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    • 제9권1호
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    • pp.111-119
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    • 1995
  • The elastic-plastic fracture toughness($J_{IC}$) and fracture resistance (J-R curve) of SA508-3 alloy steel used for nuclear reactor pressure vessel are investigated by using CT-type specimens. Fracture toughness tests are conducted by unloading compliance method and multiple specimen method at room temperature, -2$0^{\circ}C$ and 20$0^{\circ}C$. The apparent negative crack growth phenomenon which usually arises in partial unloading compliance test is well known. The negative crack growth phenomenon in determining J sub(IC) or J-R cure from partial unloading compliance experiments may be eliminated by the offset technique. In this study, the evaluation of $J_{IC}$ multiple specimen method recommended by the JSME gives the most reliable results by using half-size CT(similar-type) specimens.

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반경방향의 모서리 균열을 갖고 내면이 경사기능재료(FGM)로 코팅된 두꺼운 실린더의 겉보기 파괴인성해석 (Analysis of Apparent Fracture Toughness of a Thick-Walled Cylinder with an FGM Coating at the Inner Surface Containing a Radial Edge Crack)

  • 알리 모하마드 압사;라셀;송정일
    • Composites Research
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    • 제23권2호
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    • pp.1-9
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    • 2010
  • 본 연구는 실린더 내부가 경사가능재료로 코팅된 두꺼운 벽을 가진 실린더의 겉보기 파괴인성치를 해석한 것이다. 실린더는 내부로부터 반경방향의 단일 모서리 균열이 내재되어 있으며, 균열면과 내면에는 내압을 받고 있는 것으로 가정하였다. 소결온도로부터 냉각 결과 균일한 열팽창계수로 인해 실린더에는 비적합 고유스트레인이 생성되었다. 기존의 연구에서 소개된 응력확대계수 평가법에 기초해 겉보기 파괴인성치를 계산하였다. 본 연구에서는 TiC/$Al_{2}O_{3}$ FGM 코팅된 실린더를 사용하였고 겉보기 파괴인성치의 수치적인 결과를 도식화하였다. 재료분포프로파일, 실린더 벽 두께, 적용온도와 코팅두께등이 겉보기 파괴인치에 미치는 영향이 상세히 조사되었으며, 이러한 모든 인자는 실린더의 겉보기 파괴인성치를 조절하는데 중요한 역할을 하는 것으로 밝혀졌다.

Evaluation Method of Adhesive Fracture Toughness Based on Double Cantilever Beam (DCB) Tests Including Residual Thermal Stresses

  • Yokozeki, Tomohiro;Ogasawara, Toshio
    • Advanced Composite Materials
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    • 제17권3호
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    • pp.301-317
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    • 2008
  • The energy release rate associated with crack growth in adhesive double cantilever beam (DCB) specimens, including the effect of residual stresses, was formulated using beam theory. Because of the rotation of the asymmetric arms in the adhesive DCB specimens due to temperature change, it is necessary to correct the evaluated fracture toughness of the DCB specimens, specifically in the case of a large temperature change. This study shows that the difference between the true toughness and an apparent toughness due to the consequence of ignoring residual stresses can be calculated for a given specimen geometry and thermo-mechanical properties (e.g. coefficient of thermal expansion). The calculated difference in the energy release rates based on the present correction method is compared with that from FEM in order to verify the present correction method. The residual stress effects on the evaluation of the adhesive fracture toughness are discussed.

압자압입시험에 의한 이종재료 접합층의 계면인성 평가 (Evaluation of Apparent Interface Toughness of Composites Layers by Indentation Test)

  • 송준희;김학근;임재규
    • 대한기계학회논문집A
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    • 제26권10호
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    • pp.2089-2095
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    • 2002
  • Ceramic/metal composites have many attractive properties and great potential fur applications. Interfacial fracture properties of different layered composites are important in material integrity. Therefore, evaluation of fracture toughness at interface is required in essence. In this study, the mechanical characteristics for interface of ceramic/metal composites were investigated by indentation test of micro-hardness method. Apparent interfacial toughness of TBC system could be determined with a relation between the applied load and the length of the crack formed at the interface by indentation test.

제하 컴플라이언스법에 의한 SA533B강의 $J_1C$ 및 J-R 곡선에 미치는 열시효 영향 (Effects of Accelerated Iso-Thermal Aging on Elastic-Plastic Fracture Toughness and Fracture Resistance Curve by Unloading Compliance Method in SA533B Low Alloy Steel)

  • 윤한기;차귀준
    • 한국해양공학회지
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    • 제8권2호
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    • pp.157-165
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    • 1994
  • Effect of an accelerated iso-thermal aging (375 degree C x 66days, 375 degree C x 200days) on elastic-plastic fracture resistance curve were examined in SA533B low alloy steel. Fracture toughness test are conducted by unloading compliance method at room temperature. But the apparent negative crack growth phenomenon, usually arise in partial unloading compliance test. The phenomenon of negative crack growth may be eliminated by the offset technique. There is no effect of aging on J sub(IC) and dJ/da in iso-thermal aged (375 degree C x 66 days) specimen, but there is very little effect in iso-thermal aged (375 degree C x 200 days) specimen.

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3Y-TZP의 기계적 물성에 미치는 영향: (I) 단사정지르코니아의 첨가 (Effect on Mechanical Properties of 3Y-TZP; (I) Addition of Monoclinic Zirconia)

  • 양성구;배경만;조범래;강종봉
    • 한국세라믹학회지
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    • 제42권6호
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    • pp.411-416
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    • 2005
  • Y-TZP(Yttria-stabilized Tetragonal Zirconia Polycrystal) ceramics are of great interest as engineering and structural materials due to their excellent mechanical properties arising from transformation toughening, it is also reported that the 3Y-TZP($3 mol\%$ Yttria-stabilized Tetragonal Zirconia Polycrystal) has the best mechanical properties in Y-TZP ceramics. But to use widely for engineering and structural materials, it remains an important challenge to be able to improve its fracture toughness. In order to produce the 3Y- TZP ceramics showing much better mechanical properties, milling method adding monoclinic zirconia to 3Y-TZP was adopted and the resultant mechanical properties containing apparent density and fracture toughness were measured by using proper techniques. Experimental results showed that the 3Y-TZP specimen containing $33 wt\%$ of monoclinic zirconia, which was sintered at $1450^{\circ}C$, has the highest fracture toughness value of $11.38 MPa{\cdot}m^{1/2}$ which is three times higher than that of normal 3Y-TZP ceramics.