• Title, Summary, Keyword: 등방성체

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Dynamic Mode III Crack Propagated with Constant Velocity at Interface Between Isotropic and Orthotropic Material (등방성체와 직교이방성체의 접합계면네 내재된 동적모드 III 균열의 등속전파)

  • Lee, Gwang-Ho;Hwang, Jae-Seok;Yu, Jae-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.12
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    • pp.3828-3837
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    • 1996
  • The dynamic problems of interface crack propagated with constant velocity along the interface of bimateraial composed of isotropic and orthotropicmaterial under antiplane loading condition are studied in this paper. The general dynamic stress fields and displacement fields of mode III are derived when interface crack between isotropic and orthotropic material is propagating with constant velocity. The general dynamic stress fields and displacement fields in isotropic material. Finally, the characteristics of interface crack propagation are studied with various properties of isotropic and orthotropic material and crack propagarion velocities.

Application of the Static Photoelastic Experimental Hybrid Method to the Crack Propagation Criterion for Isotropic Materials (등방성체의 균열전파 기준에 정적 광탄성 실험 하이브리드 법 적용)

  • Shin Dong-Chul;Hawong Jai-Sug;Nam Sung-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.8
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    • pp.1229-1236
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    • 2004
  • The specimen materials used in this research are isotropic epoxy resins. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (r) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of isotropic epoxy resin.

Development of Dynamic Photoelastic Experimental Hybrid Method for Propagating Cracks in Orthotropic Material (직교이방성체내의 진전 균열에 대한 동적 광탄성 실험 Hybrid 법 개발)

  • Shin, Dong-Chul;Hawong, Jai-Sug;Sung, Jong-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.8
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    • pp.1273-1280
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    • 2003
  • In this paper, transparent dynamic photoelastic experimental hybrid method for propagating cracks in orthotropic material was developed. Using transparent dynamic photoelastic experimental hybrid method, we can obtain stress intensity factor and separate the stress components from only isochromatic fringe patterns without using isoclinics. When crack is propagated with constant velocity, the contours of stress components in the vicinity of crack tip in orthotropic material are similar to those of isotropic material or orthotropic material with stationary crack under the static load. Dynamic stress intensity factors are decreased as crack growths. It was certified that the dynamic photoelastic experimental hybrid method was very useful for the analysis of the dynamic fracture mechanics.

Development of Dynamic Photoelastic Experimental Hybrid method for Propagating Cracks in Orthotropic Material (직교이방성체내의 진전 균열에 대한 동적 광탄성 실험의 Hybrid 법 개발)

  • Shin, Dong-Chul;Hawong, Jai-Sug
    • Proceedings of the KSME Conference
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    • pp.236-241
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    • 2000
  • In this paper, transparent dynamic photoelastic experimental hybrid method for propagating cracks in orthotropic material is developed. Using transparent dynamic photoelastic experimental hybrid method, we can obtain stress intensity factor and separate the stress components from only isochromatic fringe patterns without using isoclinics. It is certified that the dynamic photoelastic experimental hybrid method is very useful for the problems of the dynamic tincture mechanics.

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순수 굽힘 모멘트 장치와 순수 전단력 장치에 관한 고찰

  • 황재석
    • Journal of the KSME
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    • v.32 no.6
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    • pp.536-553
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    • 1992
  • 하중 종류 중에서 가장 기본적인 하중 중의 하나인 순수 전단력과 순수 굽힘 모멘트를 발생시 키고자 할 때는 아래와 같은 장치를 사용하는 것이 좋다. 1) 등방성체나 이방성체의 횡 전단계수 (G$_{12}$)와 횡 응력 프린지치(f$_{12}$) 등을 측정 하고자 할 때, 또는 모드 II (mode II)상태의 파괴역학을 연구하고자 할 때는 그림 1, 그림 2, 그림 3 그리고 그림 4 등에 제시된 것 중에서 적당한 것을 사용할 수 있다. 그러나 순수 전단 력이 발생되는 면적이 크고, 순수 전단력을 정확하고 균일하게 발생시키고자 할 때, 각 재료의 전단 물성치(shear properties) 측정, 모드II(mode II) 상태의 파괴역학을 연구하고자 할 때는 본 연구자가 고안한 H.I.S.T. 장치를 이용하면 편리하다. 2) 직선 보에 순수 굽힘 모멘트를 균일하고 정확하게 가하고자 할 대는 N.B.M.장치를 사용하는 것이 좋다. 또 N.B.M. 장치는 어느 보의 장치보다도 곡선보나 변형이 큰 보에도 더 정확하고 균일하게 순수 굽힘 모멘트를 발생시킬 수 있다.

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Analysis of Propagating Crack In Isotropic Material under Dynamic Mode I Constant Displacement (동적모드 I 등변위상태하에서 전파하는 등방성체의 균열해석)

  • Lee, Gwang-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.8
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    • pp.2007-2014
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    • 2000
  • It has been reported that the dynamic stress intensity factor for a propagating crack is increasing or decreasing according to the increasement of the crack propagating velocity. It is confirmed in this study that the increasement or decreasement of stress intensity factor with crack growing velocity is accused by loading condition. When the crack propagates under a constant displacement along upper and lower boundary in finite plate, the dynamic stress intensity factor decreases according to the increasement of the propagating crack velocity. When the crack propagates under a constant stress along upper and lower boundary in finite plate, the dynamic stress intensity factor increases according to the increasement of the propagating crack velocity. The increasement or decreasement of stress intensity factor with crack growing velocity is greater in a fast crack propagation velocity than in a slow one.

Measurement of Stress Intensity Factor of Isotropic Material Using SPATE (SPATE에 의한 등방성체의 응력확대계수 측정)

  • Hwang, Jae-Seok;Seo, Jae-Guk;Lee, Hyo-Jae;Nam, Jeong-Hwan;Rowlangs, R.E.;Choe, Yeong-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.3
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    • pp.393-404
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    • 1997
  • SPATE(Stress Pattern Analysis by Thermal Emission) can be effectively used to analyze the stress distributions of isotropic structure under the repeated load by non-contact. In this research, the measuring method and the measuring concept of stress intensity factor of isotropic material by SPATE are suggested. The validity of the method and the concept was certified through SPATE experiment.

Analysis of Magnetic Isotropy Property using Magnetoresistance Curve of CoFe/Cu/CoFe/PtMn Multilayer Film (CoFe/Cu/CoFe/PtMn 다층박막의 자기저항 곡선을 이용한 자기 등방성 특성 분석)

  • Choi, Jong-Gu;Kim, Su-Hee;Choi, Sang-Heon;Lee, Sang-Suk;Rhee, Jang-Roh
    • Journal of the Korean Magnetics Society
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    • v.27 no.4
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    • pp.123-128
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    • 2017
  • The magnetic isotropy property from the magnetoresistance (MR) curve and magnetization (MH) loop for the PtMn based spin valve (SV) multilayer films fabricated with different the bottom structure after post-annealing treatment was investigated. The exchange biased coupling field ($H_{ex}$), coercivity ($H_c$), and MR ratio of Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/Ta(4 nm) SV multilayer film without antiferromagnetic PtMn layer are 0 Oe, 25 Oe, and 3.3 %, respectively. MR curve for the Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/Ta(4 nm) SV multilayer film showed $H_{ex}=2Oe$, $H_c=316Oe$, and MR (%) = 4.4 % with one butterfly MR curve having by the effect of antiferromagnetic PtMn layer. MR curve for the dualtype Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/CoFe(3 nm)/Cu(2.5 nm)/CoFe(6 nm)/Ta(4 nm) SV multilayer film showed $H_c=37.5Oe$ and 386 Oe, MR = 3.5 % and 6.5 % with two butterfly MR curves and square-like hysteresis MH loops. The anisotropy property in CoFe spin valve-PtMn multilayer is neglected by the effects of a very small value of $H_{ex}$ and a very slightly shape magnetic anisotropy. This result is possible to explain the effect of magnetization configuration spin array of the bottom SV film and the top SV film of PtMn layer.