• Title/Summary/Keyword: $J_{IC}$

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A Method to Determine the Fracture Toughness $J_{IC}$ (파괴 인성치 $J_{IC}$의 결정 방법에 관한 연구)

  • 최영환;엄윤용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.79-86
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    • 1990
  • A method to determine directly $J_{IC}$ from load-displacement curve without measuring crack growth amount is studied. A method to use key curve in determination of $J_{IC}$ is also considered. The values of $J_{IC}$ obtained from the above methods are compared with that obtained from the ASTM standard test method (E813). By performing experiments using both compact-tension specimen and three-point-bending specimen of a structural alloy steel SCM4, it is shown that the methods proposed here may be used in determination of $J_{IC}$.

Evaluation of Fracture Toughness for Steel Fiber Reinforced High Strength Concrete by Non-linear Fracture Mechanics Parameter(J-integral) (비선형 파괴역학 파라메터(J-적분)에 의한 강섬유보강 고강도콘크리트의 파괴인성 평가)

  • Koo, Bong Kuen;Kim, Tae Bong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.1
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    • pp.25-37
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    • 1993
  • This paper describes the use of the J-integral, a one parameter of the non-linear fracture mechanics(NLFM), as a means to measure toughness of steel fiber reinforced concrete. This parameter can be conveniently evaluated from experimentally determined load-deflection curves from flexural tests when a maximum-load failure criterion is employed. And, for high strength concrete which was reinforced steel fiber, with two different fiber length in the form of notched beams, were tested under 3-point bending, and $J_{IC}$, as well as the linear elastic fracture mechanics(LEFM) parameters $K_{IC}$ and $G_{IC}$ were evaluated. The results suggest that $J_{IC}$ is a promising fracture criterion for all of these. while $K_{IC}$(or $G_{IC}$) almost certainly are not. Also it was found that a fiber addition of less than 0.5% did not improve the fracture toughness of the high strength concrete. However, at more than 1.0% in fiber contents, $J_{IC}$ showed significant increases. reflecting the changed character of the concrete; $K_{IC}$ and $G_{IC}$ did not.

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A Study on the Effect of Temperature on the Elastic-Plastic Fracture Toughness $J_{IC}$ of Materials (I) - A Comparative Study of $J_{IC}$ Test Methods Recommended by ASTM and JSME - (재료의 탄소성 파괴인성치 $J_{IC}$의 온도 의존성에 관한 연구 I - AST과 JSME의 $J_{IC}$ 시험법에 관한 비교연구 -)

  • 석창성;최용식;양원호;김영진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.4
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    • pp.653-659
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    • 1989
  • Elastic-plastic fracture toughness J$_{IC}$ can be used as an effective design criterion in elastic plastic fracture mechanics. In the J$_{IC}$ test methods approved by ASTM and JSME, there are discrepancies such as the definition of J$_{IC}$, the slope of the blunting line, curve fitting method and the measurement of crack extension etc. The objective of this paper is to evaluate the effect of these discrepancies on the determination of J$_{IC}$ values. Fracture toughness tests were performed on A516, SA508 and SCM415 steels, and test results were analyzed according to ASTM E 813-81, ASTM E 813-87 and JSME S 001-1981. Results showed significant differences depending on the analysis methods. Therefore, a conversion equation between two ASTM methods was proposed, and the conversion error was within acceptable range(less then 8.5%)en 8.5%)

재료의 탄소성파괴인성치 $J_{IC}$의 온도 의존성에 관한 연구(II)

  • 석창성;최용식;양원호;김영진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.4
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    • pp.866-872
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    • 1990
  • 본 연구에서는 전보의 $J_{IC}$ 시험법 기교에 이어, 전기저항 가열로(splic furnace)와 고온용 신장계(high temperatuer extensometer)를 이용하여, 고온에서의 $J_{IC}$ 측정의 가능성을 검토하였으며, 고온용 신장계를 사용할 때와 COD게이지를 사용할 때의 $J_{IC}$값의 차이를 비교 검토하였다. 또한, 20.deg. C~600.deg. C에서, 온도 변화가 $J_{IC}$값에 미치는 영향에 대하여 고찰하여 보았다.

J_{Ic}$ evaluation of smooth and side-grooved CT specimens in submerged arc-welded SB 41 (SB41강 潛弧熔接部의 平滑 및 側面을 CT試驗片의 J_{Ic}$ 評價)

  • 오세욱;안광주;이태종
    • Journal of Welding and Joining
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    • v.4 no.1
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    • pp.47-57
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    • 1986
  • The elastic-plastic fracture toughness J_{Ic}$ of submerged arc welded structural steel $SB_{41}$ which has the properties of low strength and high ductility was discussed, especially paying attention to a comparison between two methods recommended by ASTM and JSME. $J_{IC}$ tests were carried out with compact specimens by means of R-curve, SZW, ultrasonic and electric potential methods. Based on the investigations in this study, the results obtained are as follows; (1) The JSME R-curve method gave the smallest $J_{IC}$ values which were physically closest to the crack initiation and seemed to be more practical and stable procedure between the two R-curve methods. (2) The JSME SZW method tended to slightly overestimate the $J_{IC}$ values at initiation of ductile tearing. (3) The ultrasonic and electric potential methods which also had a tendency to overestimate these $J_{IC}$ values were confirmed to be applicable and useful in determining these values. (4) The $J_{IC}$ values by the JSME R-curve method were 18.06 kgf/mm and 17.25kgf/ mm for the smooths and the side grooved CT specimen respectively.

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Trends of Standardization for IC Card (IC 카드 관련 표준화 동향 분석)

  • Park, J.M.;Han, J.H.;Chung, K.I.;Sohn, S.W.
    • Electronics and Telecommunications Trends
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    • v.15 no.3 s.63
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    • pp.50-61
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    • 2000
  • 본 논문은 차세대 IC 카드 분야에 대한 특허 및 표준화 동향 분석 결과를 기술했다. 특허의 경우, 주로 고성능 및 안전성 측면의 기술 발전에 무게를 두어 진행되고 있으며, 표준의 경우에는 ISO/IEC 등 국제 표준화 기관을 중심으로 권고안이 만들어지고 있는 실정이다. 향후, IC 카드의 효율적인 개발을 위해 지속적으로 IC 카드 관련 특허를 분석할 예정이며, 나아가 IC 카드 표준 제정에 적극 참여함으로써 기술의 우선권 확보에 기여할 예정이다.

A study on the Determination of Fracture Toughness (파괴인성치의 결정법에 대한 고찰)

  • 석창성;이환우;최용식
    • Journal of the Korean Society of Safety
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    • v.6 no.4
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    • pp.73-80
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    • 1991
  • Interest in fracture of structure has increased significantly over the past decade. New approaches to analyze structural performance have been accompanied by the development of test methods to characterize material behavior in a manner compatible with the analysis. Several test methods have been developed as a results of advances in fracture mechanics, for example, $K_{IC}$ , $J_{IC}$, R-curve tearing instability and CTOD approaches. Among the rest, fracture toughness $K_{IC}$ and $J_{IC}$ can be used as an effective design criterion in fracture mechanics. Generally, the determintion of $J_{IC}$ was performed according to ASTM E 813 or JSME S 001 and $K_{IC}$ was performed according to ASTM E 399. In this study, the test method for $K_{IC}$ and $J_{IC}$ were discussed.scussed.

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A novel semi-empirical technique for improving API X70 pipeline steel fracture toughness test data

  • Mohammad Reza Movahedi;Sayyed Hojjat Hashemi
    • Steel and Composite Structures
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    • v.51 no.4
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    • pp.351-361
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    • 2024
  • Accurate measurement of KIC values for gas pipeline steels is important for assessing pipe safety using failure assessment diagrams. As direct measurement of KIC was impossible for the API X70 pipeline steel, multi-specimen fracture tests were conducted to measure JIC using three-point bend geometry. The J values were calculated from load-displacement (F-δ) plots, and the associated crack extensions were measured from the fracture surface of test specimens. Valid data points were found for the constructed J-Δa plot resulting in JIC=356kN/m. More data points were added analytically to the J-Δa plot to increase the number of data points without performing additional experiments for different J-Δa zones where test data was unavailable. Consequently, displacement (δ) and crack-growth (Δa) from multi-specimen tests (with small displacements) were used simultaneously, resulting in the variation of Δa-δ (crack growth law) and δ-Δa obtained for this steel. For new Δa values, corresponding δ values were first calculated from δ-Δa. Then, corresponding J values for the obtained δ values were calculated from the area under the F-δ record of a full-fractured specimen (with large displacement). Given Δa and J values for new data points, the developed J-Δa plot with extra data points yielded a satisfactory estimation of JIC=345kN/m with only a -3.1% error. This is promising and showed that the developed technique could ease the estimation of JIC significantly and reduce the time and cost of expensive extra fracture toughness tests.

J-Integral Evaluation of Concrete Fracture Characteristics

  • Choi, Sin-Ho;Kye, Hae-Ju;Kim, Wha-Jung
    • International Journal of Concrete Structures and Materials
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    • v.18 no.3E
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    • pp.183-189
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    • 2006
  • Many researchers have recently proposed various parameters, variables of models and experimental methods to evaluate fracture properties of concrete, and their developments allow us to analyze the non-linear and quasi-brittle fracture mechanisms. This paper presents a brief treatment of the fracture parameters. Additionally, three-point bending tests were conducted to compare J-integral($J_{Ic}$) with other parameters($K_{Ic},\;G_{Ic},\;and\;G_F$). The change in parameter values with respect to the width and notch length of concrete beam specimens was also considered. The load-displacement curves were used to measure the concrete fracture toughness experimentally. From the results of experiment, it was found that the value of $G_F\;and\;J_{Ic}$ decreased as the notch depth increased and that $G_F$ was less sensitive than $J_{Ic}$. Therefore, the former, $G_F$, is more appropriate in using it as the concrete fracture toughness parameter. The values of $G_F\;and\;J_{Ic}$ increased when the width of concrete specimens increasing from 75 mm to 150 mm. Thus, the effects of the specimen width should be considered in determining the fracture toughness of concrete.