• 전산구조공학
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• 제10권4호
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• pp.217-228
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• 1997

p-version 유한요소법에 의한 고정밀해석은 응력특이가 발생하는 선형탄성 문제에 매우 적합한 방법으로 인식되고 있다. 해석 결과의 정확도, 모델링의 단순성, 입력자료에 대한 통용성 및 사용자와 CPU 시간의 절감 등 여러장점이 선형탄성 문제에 적용되어 우수성이 입증되었지만, 탄소성 해석분야는 아직 적용이 이루어지지 않고 있다. 그러므로 본 논문에서는 일-경화재료에 대한 구성방정식을 이용하여 정식화된 증분소성이론과 소성유동법칙에 근거한 재료비선형 p-version 유한요소모델이 제안되었다. 비선형방정식을 풀기 위해 Newton-Raphson법과 초기강성도법 등의 반복법이 모색되었다. 제안된 모델을 이용하여 개구부를 가진 사각형 평판과 내압을 받는 두꺼운 실린더, 그리고 등분포하중을 받는 원판해석 등의 수치실험이 수행되었다. 한편, p-version 모델에 의한 해석결과는 문헌의 이론값과 상용유한요소프로그램인 ADINA의 해석결과와 비교 검증되었다.

• Composites Research
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• 제13권1호
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• pp.69-77
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• 2000

본 논문에서는 크기가 일정한 비증분 하중과 크기가 커서 증분이론을 사용해야만 하는 증분하중이 동시에 가해지는 구조물의 비선형 해석을 위한 수정 호길이법을 제시한다. 수정된 호길이법에서는 비선형 계산을 수행할 때 증분하중에 의한 변위와 비증분 하중에 의한 변위를 구분하여 처리하게 된다. 제안된 방법의 타당성은 내압, 외압 및 압축하중을 받는 쉘 구조물의 비선형 거동에 대한 기존 결과와의 비교를 통해 검토하였다. 또한 비증분 하중과 증분하중이 함께 가해지는 대표적인 경우로서, 일정 횡압력과 축방향 증분 압축하중을 동시에 받는 쉘 구조물의 비선형 좌굴거동에 대한 인자연구를 수행하였다.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.54-62
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• 1998

In this study, collapse behavior of frame composed of thin-walled rectangular tube is investigated. Considering the collapse of frame, the bending and compression members undergo large deformation. The stiffness of the compound element is obtained from analytical moment-rotation relationship and approximated load-deflection relationsh- ip of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state of each element for bending and compression.

• Earthquakes and Structures
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• 제6권6호
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• pp.611-625
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• 2014

This paper presents a simple methodology that integrates an improved storey shear modelling, Incremental Dynamic Analysis and Monte Carlo Simulation in order to carryout vulnerability analysis towards development of fragility curves for Unreinforced Brick Masonry buildings. The methodology is demonstrated by developing fragility curves of a single storey Unreinforced Brick Masonry building for which results of experiment under lateral load is available in the literature. In the study presented, both uncertainties in mechanical properties of masonry and uncertainties in the characteristics of earthquake ground motion are included. The research significance of the methodology proposed is that, it accommodates a new method of damage grade classification which is based on 'structural performance characteristics' instead of 'fixed limiting values'. The usefulness of such definition is discussed as against the existing practice.

• 한국해양공학회지
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• 제2권2호
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• pp.71-77
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• 1988

For the collapse of structures due to the variable repeated load, two types of collapse mechanisms, i.e., incremental collapse and alternating plasticity, exist. Under the similar variable repeated loading conditions there exists shakedown state in the structures. In shakedown state, the number of plastic hinges are not increased and all further loading will be resulted in the elastic moment changes. Namely, under the shakedown state, structures do not collapse. In this investigation, shakedown analysis are performed by composing new computer programs. Basic theories employed to compose the programs are as follows. 1. Newton-Raphson methods are added to the existing matrix method for the plastic analysis. 2. An effort to construct the stiffness of axial and bending springs attached at both ends of the member has been made. By using the programs developed, it is possible to anticipate the collapse mechanisms (Incremental collapse, alternating plasticity). Lastly for the verification of performance of the program, demonstration examples have been solved and the results are compared with other sources.

• 대한기계학회논문집
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• 제12권2호
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• pp.231-240
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• 1988

본 연구에서는 외압을 받는 공기윤활 저어널 베어링의 정적인 경우에 대해 증분법과 유한요소법을 적용하고 유량계수는 실험을 근거로 하여 포켓에서 베어링 내부로 유입될 때의 유압손실을 고려한 Pink와 Stout의 값을 이용하였다.

• 소성∙가공
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• 제21권4호
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• pp.234-239
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• 2012

This study examines the forming properties and forming loads needed to increase the edge thickness on the external face of a plate using finite element analysis(FEA). Recently, forming optimization techniques within FEA are being extensively used in designing the optimal forming conditions for processes like forging, extrusion, rolling, and spinning. Most of these existing forming operations involve reducing the volume per unit length, but research for increasing volume per unit length is not very extensive. For this study we chose an automotive engine flywheel which is a welded assembly of a plate and a gear with each component having a different thickness. We considered a forming technique to increase the thickness in order to allow the machining of the gear directly on the external face of plate alleviating the need for a weld. To study various forming techniques, we used the finite element method with the flow stress of material and incremental forming steps. We conclude from this study that the analysis of forming properties and forming loads by using the finite element analysis and testing is useful as a method to increase the thickness per unit length.

• 대한전기학회논문지:전력기술부문A
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• 제53권1호
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• pp.1-6
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• 2004

This paper suggests an extended power flow analysis algorithm based on a modified economic load dispatch concept. Meaningfully, the proposed method makes it possible to perform the power flow analysis without a slack bus. And the 'equal incremental cost' rule which is obtained by economic load dispatch prior to power flow is maintained even during the proposed power flow analysis. In this paper, both 5 - bus and 14 - bus power systems are used to offer the theoretical accuracy and practical applications of this algorithm.

• Structural Engineering and Mechanics
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• 제51권6호
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• pp.955-971
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• 2014

Large post-buckling behavior of Timoshenko beams subjected to non-follower axial compression loads are studied in this paper by using the total Lagrangian Timoshenko beam element approximation. Two types of support conditions for the beams are considered. In the case of beams subjected to compression loads, load rise causes compressible forces end therefore buckling and post-buckling phenomena occurs. It is known that post-buckling problems are geometrically nonlinear problems. The considered highly non-linear problem is solved considering full geometric non-linearity by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. There is no restriction on the magnitudes of deflections and rotations in contradistinction to von-Karman strain displacement relations of the beam. The beams considered in numerical examples are made of lower-Carbon Steel. In the study, the relationships between deflections, rotational angles, critical buckling loads, post-buckling configuration, Cauchy stress of the beams and load rising are illustrated in detail in post-buckling case.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.327-334
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• 2001

This paper presents a non-linear analysis procedure for plane frame structures by finite element formulation with assumptions of Timoshenko beam theory. Finite element displacement method based on Lagrangian formulation is used and two-noded and isoparametric line element is adopted to represent finite element model. The layered approach is used for the elasto-plastic analysis of the plane frame structures with rectangular and I cross sections. A load incremental method combined with the tangent stiffness and the initial stiffness methods for each load increment is used for the solution of non-linear equations. Numerical examples are presented to investigate the behavior and the accuracy of the elasto-plastic non-linear application and the results of this study are compared with other solutions using the concept of plastic hinge.