• 제목, 요약, 키워드: initial shape analysis

검색결과 523건 처리시간 0.039초

막구조의 초기형상 및 재단도 결정알고리즘에 관한 연구 (A Study on the Shape Finding and Patterning Procedures for Membrane Structures)

  • 한상을;이경수;이상주;유용주
    • 한국전산구조공학회:학술대회논문집
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    • pp.298-305
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    • 1998
  • The purpose of this study is to propose the method of determining the initial fabric membrane structures surface and membrane patterning procedures. Tension structure, such as, fabric membrane structures and cable-net, is stabilized by their initial prestress and boundary condition. The process to find initial structural overall shape of tension structures produced by initial prestress called Shape Finding or Shape Analysis. One of the most important factor for the design of membrane structures is to search initial smooth surface, because unlike steel or concrete building elements which resist loads in bending, all tension structure forces are carried within the surface by membrane stress or cable tension. To obtain initial surface of fabric membrane element in large deformation analysis, the membrane element is idealized as cable using a technique with Force-density method. and that result is compared with well-known nonlinear numerical method, such as Newton-raphson method and Dynamic relaxation method. The shape resulting from Force-density method has been dealt with as the initial membrane shape and used patterning procedures.

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제어기법에 따른 비선형 형상해석의 수렴성 및 효율성 펑가 (An Estimate for Convergence and Efficiency of Nonlinear Shape Analysis According to the Control Techniques)

  • 정을석;전진형;손수덕;김승덕
    • 한국공간구조학회:학술대회논문집
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    • pp.214-223
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    • 2006
  • Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and happen large deformation phenomenon. Therefore, in this study, to find the structural shape after large deformation caused by initial stress, we need the shape analysis considering geometric nonlinear term. And we investigate the evaluation of shape analysis technique's convergence and efficiency according to the control method

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막 구조물의 측지선을 이용한 재단도 생성에 관한 연구 (A Study on Cutting Pattern Generation of Membrane Structures by Using Geometric Line)

  • 안상길;손수덕;김승덕
    • 한국공간구조학회:학술대회논문집
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    • pp.125-132
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    • 2005
  • Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and it happens large deformation phenomenon. And also there are highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore, in this study, to find the structural shape after large deformation caused by Initial stress, we need the shape analysis considering geometric nonlinear ten And the geodesic line on surface of initial equilibrium shape and the cutting pattern generation using the geodesic line is introduced.

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막구조물의 준공평형 형상해석에 관한 연구 (A Study on the Actual Equilibrium Analysis for Membrane Structures)

  • 이장복;김재열;권택진
    • 한국전산구조공학회:학술대회논문집
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    • pp.61-68
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    • 2000
  • In general, the design of membrane structures takes three steps. The first is shape finding analysis which is determination of initial equilibrium geometry with uniform stresses. The second step involve the computation of the stress-deformation to get completed membrane under various load conditions. The third step is to divide the membrane structures into several plan strips from the initial equilibrium states. This procedure is needed because of the initial shape has usually undevelopable curved surface and is called as "cutting patterns generation". By introducing this work, the deformation due to the initial stress is removed and approximate cutting patterns are generated. In this approach, however, material properties is not considered, therefore the error between the design stresses and actual stresses during the fabrication of plan strips should be occurred. In this paper, actual equilibrium shape analysis procedure for HP shape models is presented. The deviations of stresses between the design stresses and actual stresses are estimated.

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장력안정 구조물의 최적초기응력 탐색에 관한 연구 (A Study on the Optimal Initial Stress-Finding of Structures Stabilized by Cable-Tension)

  • 최옥훈;한상을;권택진
    • 한국전산구조공학회:학술대회논문집
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    • pp.287-294
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    • 1999
  • The tensegrity structure by prestressed cable, which may have large freedom in scale and form and therefore are received much attention from the view points of their light weight and aesthetics, is a very flexible and geometrically unstable structure because the cable material has little initial rigidity. For the stable self-equilibrated state of the usually very deformable structure, the method to find the optimal initial stress by the shape analysis is proposed in this paper. The proposed procedure is to derive the nonlinear finite element formula of cable and truss members considering geometric nonlinearity and used to modified load incremental method adding to Newton-Raphson method with the proposed condition for optimal initial stress. The result of the shape analysis for the tensegrity structure with the radius of 30m is shown the almost approximated shape to architectural shape and the changed procedure of initial stress

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고정하중을 받는 현수교 시스템의 초기형상 결정법 (Initial Shape Analysis of Suspension Bridge System under Dead Load)

  • 김민;김문영
    • 한국강구조학회 논문집
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    • v.22 no.6
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    • pp.511-521
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    • 2010
  • 현수교에서 행어와 만나는 보강거더 정착부의 제로변위(zero displacement)법과 주탑의 케이블 정착부 및 주 케이블과 행어가 만나는 절점에서 힘의 평형조건을 이용하여 현수교 주 케이블의 수평장력 초기평형상태를 결정하기 위한 해석법을 제시한다. 이 방법은, 기존 연구자들의 복잡한 비선형 해석을 통한 현수교 케이블의 해석에 비해 적은 노력으로 주 케이블의 정확한 수평장력 및 초기형상을 결정할 수 있는 효과적인 방법이다. 2차원 및 3차원 현수교 수치해석 예제들로부터 앞선 연구자들의 해석결과와 비교, 검토를 통하여 본 연구의 정확성과 타당성을 입증한다.

초기 속도법을 이용한 최적 블랭크 설계 프로그램의 개발 (Development of Optimal Blank Shape Design Program Using the Initial Velocity of Boundary Nodes)

  • 심현보;이상헌;손기찬
    • 한국소성가공학회:학술대회논문집
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    • pp.77-81
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    • 2002
  • A new method of optimal blank shape design using the initial nodal velocity (INOV) has been proposed for the drawings of arbitrary shaped cups. With the given information of tool shape and the final product shape, corresponding initial blank shape has been found from the motion of boundary nodes. Although the sensitivity method, the past work of Hynbo Shim and Kichan Son, has been proved to be excellent method to find optimal blank shapes, the method has a problem that a couple of deformation analysis is required at each design step and it also exhibits an abnormal behaviors in the rigid body rotation prevailing region. In the present method INOV, only a single deformation analysis per each design stage is required. Drawings of practical products as well as oil-pan have been chosen as the examples. At every case the optimal blank shapes have been obtained only after a few times of modification without predetermined deformation path. The deformed shape with predicted optimal blank almost coincides with the target shape at every case. Through the investigation the INOV is found to be very effective in the arbitrary shaped drawing process design.

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초기 속도법을 이용한 최적 블랭크 설계 프로그램의 개발 (Development of Optimal Blank Shape Design Program Using the Initial Velocity of Boundary Nodes)

  • 심현보;이상헌;손기찬
    • 소성가공
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    • v.11 no.6
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    • pp.487-494
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    • 2002
  • A new method of optimal blank shape design using the initial nodal velocity (INOV) has been proposed for the drawings of arbitrary shaped cups. With the given information of tool shape and the final product shape, corresponding initial blank shape has been found from the motion of boundary nodes. Although the sensitivity method, the past work of the present authors, has been proved to be excellent method to find optimal blank shapes, the method has a problem that a couple of deformation analysis is required at each design step and it also exhibits an abnormal behaviors in the rigid body rotation prevailing region. In the present method INOV, only a single deformation analysis per each design stage is required. Drawings of practical products as well as oil-pan, have been chosen as the examples. At every case the optimal blank shapes have been obtained only after a few times of modification without predetermined deformation path. The deformed shape with predicted optimal blank almost coincides with the target shape at every case. Through the investigation the INOV is found to be very effective in the arbitrary shaped drawing process design.

금형보정 모듈을 이용한 초고강도강 자동차부품용 프레스금형의 자동보정 (Automatic Tool Compensation for an UHSS Automotive Component Using a Compensation Module)

  • 이정흠;김세호
    • 소성가공
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    • v.25 no.2
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    • pp.109-115
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    • 2016
  • In the current study, automatic tool compensation is accomplished by using a finite element stamping analysis for a center roof rail made of UHSS in order to satisfy the specifications for shape accuracy. The initial blank shape is calculated from a finite element inverse analysis and potential forming defects such as tearing and wrinkling are determined by the finite element stamping analysis based on the initial tool shape. The blank shape is optimized to meet the shape requirements of the final product with the stamping analysis, and die compensation is determined with the information about springback. The specifications for shape accuracy were successfully achieved by the proposed die compensation scheme using the finite element stamping analysis. The current study demonstrates that the compensation tendency is similar when the proposed scheme is used or when the compensation is performed by trial and error in the press-shop. This similarity verifies that the automatic compensation scheme can be used effectively in the first stage of tool design especially for components made from UHSS.

직접 격자 사상법을 이용한 직사각컵 및 S-Rail 성형공정의 3차원 유한요소 역해석 (Three Dimensional Finite Element Inverse Analysis of Rectangular Cup and S-Rail Forming Processes using a Direct Mesh Mapping Method)

  • 김승호;허훈
    • 한국소성가공학회:학술대회논문집
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    • pp.81-84
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    • 2001
  • An inverse finite element approach is employed for more capability to design the optimum blank shape from the desired final shape with small amount of computation time and effort. In some drawing or stamping simulation with inverse method, it is difficult to apply inverse scheme due to the large aspect ratio or steep vertical angle of inclination. The reason is that initial guesses are hard to make out with present method for those cases. In this paper, a direct mesh marring scheme to generate initial guess on the sliding constraint surface described by finite element patches is suggested for one step inverse analysis to calculate initial blank shape. Radial type mapping is adopted for the simulation of rectangular cup drawing process with large aspect ratio and parallel type mapping for the simulation of S-Rail forming process with steep vertical angle of inclination.

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