• 제목, 요약, 키워드: Inhomogeneous

검색결과 623건 처리시간 0.039초

비균질재료의 표면균열에 대한 응력확대계수 해석 (Stress Intensity Factor Analysis for Surface Crack in Inhomogeneous Materials)

  • 김준수;이준성
    • 한국정밀공학회:학술대회논문집
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    • pp.816-819
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    • 2002
  • Accurate stress intensity factor analyses and crack growth rate of surface-cracked components in inhomogeneous materials are needed for reliable prediction of their fatigue lift and fracture strengths. This paper describes an automated system for analyzing the stress intensity factors of three-dimensional (3D) cracks in inhomogeneous materials. 3D finite element method (FEM) was used to obtain the stress intensity factor for subsurface cracks and surface cracks existing in inhomogeneous materials. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in a plate subjected to uniform tension is calculated, and compared with Raju-Newman's solutions. Then the system is applied to analyze cladding effect of subsurface cracks in inhomogeneous materials. The results were compared with those surface cracks in homogeneous materials. It is clearly demonstrated from these analyses that the stress intensity factors for subsurface cracks are less than those of surface cracks.

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불균질 매질에 따른 인공 합성 탄성파 자료 비교 (Comparison of synthetic seismograms referred to inhomogeneous medium)

  • 김영완;장성형;윤왕중;서상용
    • 한국지구물리탐사학회:학술대회논문집
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    • pp.197-202
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    • 2007
  • Most of seismic reflection prospecting assumes subsurface formation to be homogeneous media. These models are not capable of estimating small scale heterogeneity which is verified by well log data or drilling core. And those synthetic seismograms by homogeneous media are limited to explain various changes at field data. So we developed a inhomogeneous velocity model which can estimate inhomogeneity of background medium to implement numerical modeling from homogeneous medium and inhomogeneous medium on the model. Background medium using three autocorrelation functions in order to generate inhomogeneous velocity media was according to dominant wavelength of background medium and correlation length of random medium. And then we compared shot gathers. The results show that numerical modeling implemented at inhomogeneous medium depicts complex wave propagation of field data.

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비균질재료의 3차원 균열에 대한 응력확대계수 해석 (Stress Intensity factor Analysis for Three-Dimensional Cracks in Inhomogeneous Materials)

  • 김준수;이준성
    • 한국정밀공학회지
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    • v.20 no.4
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    • pp.197-203
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    • 2003
  • Accurate stress intensity factor analyses and crack growth rate of surface -cracked components in inhomogeneous materials are needed fur reliable prediction of their fatigue life and fracture strengths. This paper describes an automated stress intensity factor analysis of three-dimensional (3D) cracks in inhomogeneous materials. 3D finite element method (FEM) was used to obtain the stress intensity factor fur subsurface cracks and surface cracks existing in inhomogeneous materials. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in a plate subjected to uniform tension is calculated, and compared with Raju-Newman's solutions. Then the system is applied to analyze cladding effect of subsurface cracks in inhomogeneous materials. The results were compared with those surface cracks in homogeneous materials. It is clearly demonstrated from these analyses that the stress intensity factors for subsurface cracks are less than those of surface cracks. Also, this system is applied to analyze cladding effect of surface cracks in inhomogeneous materials.

Conversion of Extraordinary Waves into Upper Hybrid Waves in Inhomogeneous Plasmas

  • Kim, Gyeong-Seop;Kim, Eun-Hwa;Lee, Dong-Hun
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • pp.35-35
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    • 2004
  • Inhomogeneity Is important in wave coupling and mode conversion. We numerically examine the conversion of extraordinary(X) waves into upper hybrid(UH) waves in inhomogeneous plasmas by using a three-dimensional multi-fluid numerical model. A one-dimensional Inhomogeneous density profile is assumed in a cold and collisionless plasma. The density gradient is taken to be perpendicular to the magnetic field. An impulsive input is assumed to excite the X waves in the inhomogeneous box model. (omitted)

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페라이트계 스테인리스강의 열간 압연 시 불균일 집합조직에 미치는 윤활 효과 (Effect of lubrication on the evolution of inhomogeneous textures in ferritic stainless steel sheets during hot rolling)

  • 강춘구;박수호;허무영
    • 한국소성가공학회:학술대회논문집
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    • pp.453-455
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    • 2005
  • Ferritic STS 439 Steel sheet were deformed by hot rolling with and without lubricant. The effect of friction between roll and specimen on inhomogeneous texture was studied by means of EBSD, XRD texture analysis. The textures were compared with those of obtained by Taylor FEM simulation. High friction between roll and sheet gave rise to the formation of the inhomogeneous shear texture through thickness.

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Linear and nonlinear vibrations of inhomogeneous Euler-Bernoulli beam

  • Bakalah, Ebrahim S.;Zaman, F.D.;Saleh, Khairul
    • Coupled systems mechanics
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    • v.7 no.5
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    • pp.635-647
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    • 2018
  • Dynamic problems arising from the Euler-Bernoulli beam model with inhomogeneous elastic properties are considered. The method of Green's function and perturbation theory are employed to find the deflection in the beam correct to the first-order. Eigenvalue problems appearing from transverse vibrations of inhomogeneous beams in linear and nonlinear cases are also discussed.

비균질 필터를 사용한 난류 채널 유동의 Large Eddy Simulation (Large Eddy Simulation of Turbulent Channel Flow Using Inhomogeneous Filter)

  • 이상환;김광진
    • 대한기계학회논문집B
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    • v.28 no.9
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    • pp.1022-1031
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    • 2004
  • The commutation errors by the filtering process in the large eddy simulation are considered. It is compared the conventional filter with the inhomogeneous filter that is devised to reduce the commutation errors. The weighting factor of the inhomogeneous filter suggested by Vasilyev is adopted. Also, using the optimizing function that estimates test filter width to eliminate the dissipations in the region excluding the vicinity of the wall, the flow patterns are analyzed. It is evaluated in simulations of the turbulent channel flow at Reynolds number of 1020, based on friction velocity and channel half height. Results show that the commutation errors can be significantly reduced by using the inhomogeneous filter and the optimized test filter width.

불균질 가스하이드레이트 층을 고려한 탄성파 모델링 (Seismic modeling consider of inhomogeneous gas hydrate layer)

  • 김영완;장성형;윤왕중;서상용
    • 한국신재생에너지학회:학술대회논문집
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    • pp.489-492
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    • 2007
  • The P-wave velocity at the formation which contains gas hydrate varies very wide upon gas hydrate existence. These features on seismic shot gather can not be simulated normally by numerical modeling of homogeneous medium so that we need that of random inhomogeneous medium instead. We, in this study generated random inhomogeneous medium using gaussian ACF, exponential ACF and von Karman ACF and that we supposed the random inhomogeneous medium be gas hydrate formation to execute numeric modeling. The modeling result shows the typical effect by scattering caused by random hydrate formation as is observed from seismic shot gather where hydrate exist.

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불균질 매질에서 탄성파 모델링 (Seismic Modeling for Inhomogeneous Medium)

  • 김영완;장성형;윤왕중
    • 자원환경지질
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    • v.40 no.6
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    • pp.739-749
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    • 2007
  • 탄성파 속도는 지층 물성에 따라 다양하게 분포한다. 탄성파 음원 모음도 상에 나타나는 이러한 특성은 균질 매질을 고려한 수치 모델링에서는 정상적으로 모사할 수 없으므로 무작위 불균질 매질을 고려한 수치 모델링이 필요하다. 본 연구에서는 불균질 매질 모델을 설정하고, 가우스 자기상관 함수, 지수 자기상관 함수, 폰 카르만 자기상관 함수를 이용하여 단순 지층 구조에 적용하고 각각의 특성을 살펴보았으며, 이 가운데 폰 카르만 자기상관 함수가 단파장 불균질 속도매질을 잘 표현함을 알 수 있었다. 가스 하이드레이트 수치모델링은 동해 현장자료를 바탕으로 해저면과 모델크기를 결정하였으며, 수치모델링 결과 폰 카르만 자기 상관함수가 불균질 지층구조를 포함하는 가스 하이드레이트 속도모델에서 산란현상을 가장 적절하게 구현함을 알 수 있었다. 또한 동해 탄성파 탐사자료의 탄성파 음원 모음도에서 나타나는 해저면 기인 강진폭 위상역전 반사파(BSR: bottom simulated reflector)와 산란파들이 불균질 수치 모형실험에서 적절하게 구현되었음을 알 수 있었다.

Longitudinal cracks in non-linear elastic beams exhibiting material inhomogeneity

  • Rizov, Victor I.
    • Structural Engineering and Mechanics
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    • v.71 no.2
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    • pp.153-163
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    • 2019
  • Longitudinal fracture behavior of non-linear elastic beam configurations is studied in terms of the strain energy release rate. It is assumed that the beams exhibit continuous material inhomogeneity along the width as well as along the height of the crosssection. The Ramberg-Osgood stress-strain relation is used for describing the non-linear mechanical behavior of the inhomogeneous material. A solution to strain energy release rate is derived that holds for inhomogeneous beams of arbitrary cross-section under combination of axial force and bending moments. Besides, the solution may be applied at any law of continuous distribution of the modulus of elasticity in the beam cross-section. The longitudinal crack may be located arbitrary along the beam height. The solution is used to investigate a longitudinal crack in a beam configuration of rectangular cross-section under four-point bending. The crack is located symmetrically with respect to the beam mid-span. It is assumed that the modulus of elasticity varies continuously according a cosine law in the beam cross-section. The longitudinal fracture behavior of the inhomogeneous beam is studied also by applying the J-integral approach for verification of the non-linear solution to the strain energy release rate derived in the present paper. Effects of material inhomogeneity, crack location along the beam height and non-linear mechanical behavior of the material on the longitudinal fracture behavior are evaluated. Thus, the solution derived in the present paper can be used in engineering design of inhomogeneous non-linear elastic structural members to assess the influence of various material and geometrical parameters on longitudinal fracture.