• Title/Summary/Keyword: 제하 컴플라이언스법

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

  • 오세욱;임만배;김진선
    • Journal of Ocean Engineering and Technology
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    • v.9 no.1
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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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A Study on the 43$0^{\circ}C$ Degradation Behavior of Cast Stainless Steel(CF8M) (III) - Evaluation of Elastic-Plastic Fracture Toughness - (주조 스테인리스강 CF8M의 43$0^{\circ}C$ 열화거동에 관한 연구 (III) - 탄소성 파괴인성 평가 -)

  • Gwon, Jae-Do;In, Jae-Hyeon;Park, Jung-Cheol;Choe, Seong-Jong;Park, Yun-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.10 s.181
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    • pp.2405-2412
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    • 2000
  • A cast stainless steel may experience an embrittlement when it is exposed to approximately 30$0^{\circ}C$ for long period. In the present investigation, The three classes of the thermally aged CF8M specimie n are prepared using an artificially accelerated aging method. Namely, after the specimen are held for 300, 1800 and 3600hrs. at 43$0^{\circ}C$ respectively, the specimens are quenched in water to room temperature. Load versus load line displacement curves and J-R curves are obtained using the unloading compliance method. $J_{IC}$ values are obtained following ASTM E 813-87 and ASTM E 813-81 methods. In addition to these methods, JIC values are obtained using SZW(stretch zone width) method described in JSME S 001-1981. The results of the unloading compliance method are $J_Q$=485.7 kJ/m$^2$ for virgin material, $J_{IC}$ of the degraded materials associated with 300, 1800 and 3600hrs are obtained 369.25 kJ/m$^2$, 311.02 kJ/m$^2$, 276.7 kJ/m$^2$, respectively. The results of SZW method are similar to those of the unloading compliance method. Through the elastic-plastic fracture toughness test, it is found that the value of $J_{IC}$ is decreased with increasing of the aging time. The results obtained through the investigation can provide reference data for a leak before break(LBB) of reactor coolant system of nuclear power plants.

Evaluation of J-R Curve for Aluminum 5083 Alloy Weldment by Load Ratio Analysis (Load Ratio 해석에 의한 알루미늄 5083 합금 용접부의 J-R곡선 평가)

  • 윤한기;김연겸
    • Journal of Welding and Joining
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    • v.15 no.4
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    • pp.178-186
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    • 1997
  • The purpose of this study is to evaluate the J-R curve characteristics for the 5083 aluminum alloy weldment by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agrees well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The exponential correlation of the J-R curve for the 5083 aluminum alloy base metal by the load ratio analysis is J = 93.88 ${\Delta}{\alpha}^{0.375}$. That for the weld metal and HAZ is J = 69.87 ${\Delta}{\alpha}^{0.389}$ and J = 70.59 ${\Delta}{\alpha}^{0.359}$ respectively. The J-R curve obtained by the ASTM unloading compliance method is overpredicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load displacement curve without particular crack measurement equipment.

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Validity Examination on Evaluation of J-R Curve in the Nuclear Reactor Pressure Vessel Steels and Aluminum Alloys by Load Ratio Analysis (원자로 압력용기강 및 Al 합금재의 J-R곡선평가시 Load Ratio 해석의 유효성 검토)

  • Yoon, H.K.;Woo, D.H.;Kim, Y.K.;Cha, G.J.
    • Journal of Power System Engineering
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    • v.1 no.1
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    • pp.80-90
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    • 1997
  • The purpose of this study is to evaluate the validity examination of the J-R curve characteristics for the nuclear reactor pressure vessel steels and Al alloys by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agree well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The J-R curve obtained by the ASTM unloading compliance method is over-predicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load-displacement curve without particular crack measurement equipment.

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A Study on HIGH TEMPERATURE FRACTURE TOUGHNESS of Pressure Vessel Steel SA516 at High Temperature. (압력용기용강의 고온파괴인성에 관한 연구)

  • 박경동;김정호
    • Proceedings of the KWS Conference
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    • 2001.05a
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    • pp.228-231
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    • 2001
  • Elastic-plastic fracture toughness $J_{1c}$ can be used as an effective design criterion in elastic plastic fracture mechanics. Most of these systems are operated at high temperature and $J_{1c}$ values are affected by temperature. therefore, the $J_{1c}$ valuse at high temperature must be determined for use of integrity evaluation and designing of such systems. Elastic-plastic fracture toughness $J_{1c}$ tests were performed on SA516 carbon steel plate and test results were analyzed according to ASTM E 813-8, ASTM 1813-89. Safety and integrity are required for reactor pressure vessels vecause pthey are operated in high temperature. there are single specimen method, which used as evaluation of safety and integrity for reactor pressure vessels. In this study, elastic-plastic fracture toughness$(J_{1c})$ and $J-\Delta{a}$ of SA 516/70 steel used as reactor pressure vessel steel are measured and evaluated at room Temperature, $150^{\circ}C$, $250^{\circ}C$ and $370^{\circ}C$ according to unloading compliance method.

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Evaluation on High Temperature Fracture toughness of Pressure Vessel SA516/70 Steel (압력용기용 SA516/70강의 고온파괴인성평가)

  • 박경동;김정호;윤한기;박원조
    • Journal of Ocean Engineering and Technology
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    • v.15 no.2
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    • pp.99-104
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    • 2001
  • Elastic-plastic fracture toughness $J_{lc}$ can be used as an effective design criterion in elastic plastic fracture mechanics. Most of these systems are$J_{lc}$ $J_{lc}$ value at high temperature must be determined for use of integrity evaluation and designing of such systems. Elastic-plastic fracture toughness $J_{lc}$ tests were performed on SA516/70 carbon steel plate and test results were analyzed according to ASTM E 813-87, ASTM E 813-89 and ASTM E 1152-87.safety and integrity are required for reactor pressure vessels because, they are operated in high temperature. There are single specimen method, which used as evaluation of safety and integrity for reactor pressure vessels. In this study, elastic-plastic fracture toughness($J_{lc}$) and J-$\Delta$a of SA 516/70 steel used as reactor pressure vessel steel are measured and evaluated at room temperature, 150$^{\circ}C $, 250$^{\circ}C $ and 370$^{\circ}C $ according to unloading compliance method.

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A Study on Determination of $J_{IC}$ by Time-Frequency Analysis Method (시간-주파수 해석법에 의한 $J_{IC}$결정에 관한 연구)

  • Nam, Gi-U;An, Seok-Hwan;Kim, Bong-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.5
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    • pp.765-771
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    • 2001
  • Elastic-plastic fracture toughness JIC can be used a s an effective design criterion in elastic-plastic fracture mechanics. Among the JIC test methods approved by ASTM, unloading compliance method was used in this study. In order to examine the relationship between fracture behavior of JIC test and AE signals, the post processing of AE signals has been carried out by Short Time Fourier Transform(STFT), one of the time-frequency analysis methods. The objective of this study is to evaluate the application of characterization of AE signals for unloading compliance method of JIC test. As a result of time-frequency analysis, we could extract the AE from the raw signal and analyze the frequencies in AE signal at the same time. AE signal generated by elastic-plastic fracture of material has some different aspects at elastic and plastic ranges, or the first portion of crack growth by fracture. First of all, increased energy recorded and detected by using AE count method increase rapidly from the start of ductile fracture. The variation of main frequency range with time-frequency analysis method could be confirmed. We could know fracture behavior of interior material by examination AE characteristics generated in real-time when elastic-plastic fracture occurred in material under loading.