• 제목/요약/키워드: Integral model

검색결과 1,096건 처리시간 0.039초

삼점 굽힘 시험편의 충격 거동에 있어서의 CMOD에 의한 J-적분의 계산 (Calculation of J-Integral by CMOD at Impact Behavior of 3-Point Bend Specimen)

  • 조재웅
    • 한국산학기술학회논문지
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    • 제6권6호
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    • pp.542-546
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    • 2005
  • 연성 크랙의 발생 평가를 위한 J-적분이 충격 하중을 받는 탄소성 3점 굽힘 시험편들에 대하여 연구한다. J-적분을 측정하고 평가하는 실험적인 방법이 연구되었으며 이 결과가 유한 요소법을 이용한 탄소성 이론 해석을 한 값들과 비교하여 거의 일치함을 보였다. 이론적인 수치 해석으로서도 본 연구의 유한 요소 모델로서 J-적분값을 계산할 수 있으며 삼점 굽힘 시험편의 동적 비선형 파괴 실험에 있어서 크랙 입구 개구 변위 (CMOD)에 의하여 J-적분값의 단순 계산이 가능함을 입증하였다. 탄소성 재료의 특성이 여러 가지의 충격 속도들에서 고려된다. J-적분은 충격 실험 동안 얻어진 사진들로부터 직접적으로 측정된 크랙 입구 개구 변위로부터 예측될 수 있다.

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비선형 에크만 분출 모델 (Non-Linear Ekman Pumping Model)

  • 박재현;김정환;김동균;배석태;김정렬
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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    • pp.305-306
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    • 2006
  • Developed in this study is a nonlinear Ekman pumping model to be used in simulating the rotating flows with quasi-three-dimensional Navier-Stokes equations. In this model, the Ekman pumping velocity is given from the solution of the Ekman boundary-layer equations for the region adjacent to the bottom wall of the flow domain; the boundary-layer equations are solved in the momentum-integral form. The developed model is then applied to rotating flows in a rectangular container receiving a time-periodic forcing. By comparing our results with the DNS and experimental data we have validated the developed model. We also compared our results with those given from the classical Ekman pumping model. It was found that our model can predict tile rotating flows more precisely than the classical linear model.

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비선형 Ekman 펌핑 모델의 개발 (Development of a Nonlinear Ekman Pumping Model)

  • 서용권;박재현
    • 대한기계학회논문집B
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    • 제30권6호
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    • pp.568-577
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    • 2006
  • Developed in this study is a nonlinear Ekman pumping model to be used in simulating the rotating flows with quasi-three-dimensional Navier-Stokes equations. In this model, the Ekman pumping velocity is given from the solution of the Ekman boundary-layer equations for the region adjacent to the bottom wall of the flow domain; the boundary-layer equations are solved in the momentum-integral form. The developed model is then applied to rotating flows in a rectangular container receiving a time-periodic forcing. By comparing our results with the DNS and experimental data we have validated the developed model. We also compared our results with those given from the classical Ekman pumping model. It was found that our model can predict the rotating flows more precisely than the classical linear model.

산란음장 해석을 위한 적분방정식에 대한 연구 (A study of integral equations for the analysis of scattered acoustic field)

  • Wonju Jeon;Lee, Duck-Joo
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 춘계학술대회논문집
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    • pp.1016-1019
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    • 2002
  • This paper deals with a fundamental and classical scattering problem by a finite strip. For the analysis of scattered acoustic field, a “single” integral equation is derived. Firstly, the complexity by considering the effect of the mean flow is alleviated by the introduction of Prandtl-Glauert coordinate and the new dependent variable. Secondly, the difficulty of solving the resultant strongly-coupled integral equations which always appear in this kind of 3-part mixed boundary value problem is solved by observing some good properties of the functions in complex domain and manipulating the equations and variables for the use of those properties. The solution can be obtained asymptotically in terms of gamma function and Whittaker function. One aim of this study is the improvement of methodology for the research using integral equations. The other is the basic understanding of scattering by a finite strip related to the linear cascade model of rotating fan blades.

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관측기를 갖는 2자유도 서보계의 구성에 관한 고찰 (A Study on a Two-Degree-of-Freedom Servosystem Incorporating an Observer)

  • 김영복
    • 동력기계공학회지
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    • 제3권1호
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    • pp.50-54
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    • 1999
  • In order to reject the steady-state tracking error, it is common to introduce integral compensators in servosystems for constant reference signals. However, if the mathematical model of the plant is exact and no disturbance input exists, the integral compensation is not necessary. From this point of view, a two-degree-of-freedom(2DOF) servosystem has been proposed, in which integral compensation is effective only when there is modeling error for disturbance input. The present paper considers the design problem of 2DOF servosystem incorporating an observer. It is shown that if a state feedback gain and a observer gain satisfy a condition, the integral effect does not appear when modeling error or disturbance input exists. This result means that the servosystem does not behave as a 2DOF servosystem.

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원자로 노외 중성자속 감시 시스템의 이산화 모델링 (Discretization of Ex-core Neutron Flux Monitoring System for Nuclear Rector)

  • 오현철;허섭;구인수;서용석;장문희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 하계학술대회 논문집 D
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    • pp.2678-2680
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    • 2000
  • In this paper, we calculates mathematical model of ex-core neutron flux monitoring system for nuclear reactor and design the digital system using the bilinear transformations. The output pulse shape and resolving time of the system determines from the proposed method.

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Buckling behavior of a single-layered graphene sheet resting on viscoelastic medium via nonlocal four-unknown integral model

  • Bellal, Moussa;Hebali, Habib;Heireche, Houari;Bousahla, Abdelmoumen Anis;Tounsi, Abdeldjebbar;Bourada, Fouad;Mahmoud, S.R.;Bedia, E.A. Adda;Tounsi, Abdelouahed
    • Steel and Composite Structures
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    • 제34권5호
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    • pp.643-655
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    • 2020
  • In the present work, the buckling behavior of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak's medium is studied using nonlocal four-unknown integral model. This model has a displacement field with integral terms which includes the effect of transverse shear deformation without using shear correction factors. The visco-Pasternak's medium is introduced by considering the damping effect to the classical foundation model which modeled by the linear Winkler's coefficient and Pasternak's (shear) foundation coefficient. The SLGS under consideration is subjected to compressive in- plane edge loads per unit length. The influences of many parameters such as nonlocal parameter, geometric ratio, the visco-Pasternak's coefficients, damping parameter, and mode numbers on the buckling response of the SLGSs are studied and discussed.

J-integral and fatigue life computations in the incremental plasticity analysis of large scale yielding by p-version of F.E.M.

  • Woo, Kwang S.;Hong, Chong H.;Basu, Prodyot K.
    • Structural Engineering and Mechanics
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    • 제17권1호
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    • pp.51-68
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    • 2004
  • Since the linear elastic fracture analysis has been proved to be insufficient in predicting the failure of strain hardening materials, a number of fracture concepts have been studied which remain applicable in the presence of plasticity near a crack tip. This work thereby presents a new finite element model to predict the elastic-plastic crack-tip field and fatigue life of center-cracked panels(CCP) with ductile fracture under large-scale yielding conditions. Also, this study has been carried out to investigate the path-dependence of J-integral within the plastic zone for elastic-perfectly plastic, bilinear elastic-plastic, and nonlinear elastic-plastic materials. Based on the incremental theory of plasticity, the p-version finite element is employed to account for the accurate values of J-integral, the most dominant fracture parameter, and the shape of plastic zone near a crack tip by using the J-integral method. To predict the fatigue life, the conventional Paris law has been modified by substituting the range of J-value denoted by ${\Delta}J$ for ${\Delta}K$. The experimental fatigue test is conducted with five CCP specimens to validate the accuracy of the proposed model. It is noted that the relationship between the crack length a and ${\Delta}K$ in LEFM analysis shows a strong linearity, on the other hand, the nonlinear relationship between a and ${\Delta}J$ is detected in EPFM analysis. Therefore, this trend will be depended especially in the case of large scale yielding. The numerical results by the proposed model are compared with the theoretical solutions in literatures, experimental results, and the numerical solutions by the conventional h-version of the finite element method.

GIS를 이용한 3차원정보지적도 모형 구축에 관한 연구 (Construction of 3D Information Cadastral Map Model Using GIS)

  • 오이균;양인태;유영걸;천기선
    • 한국측량학회:학술대회논문집
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    • 한국측량학회 2004년도 춘계학술발표회논문집
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    • pp.577-580
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    • 2004
  • Recently, in a field of cadastre, a computerization of cadastral map is in progress with great growth of GIS field. Also, the needs for the integration of land and building information are widely increasing for integral-management and its application of various land related information. In this study, it is constructed a 3D information cadastral map model that can make the integral management of land, building, connecting land recorders, building management ledgers, building titles, building pictures, and related attribute information.

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원형 매핑 모델을 사용하는 컴퓨터 직접 영상 재생 방식 (Computational integral imaging reconstruction method using round-type mapping model)

  • 신동학;김남우;이준재;이병국
    • 한국광학회:학술대회논문집
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    • 한국광학회 2007년도 하계학술발표회 논문집
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    • pp.259-260
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    • 2007
  • In this paper, we propose a novel computational integral imaging reconstruction (CIIR) method using round-type mapping model. Proposed CIIP method can overcome problems of non-uniformly reconstructed images caused from the conventional method and improve the resoulution of 3-D images. To show the usefulness of the proposed method, both computational experiment and optical experiment are carried out and their results are presented.

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