• Title/Summary/Keyword: membrane structures

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Comparison of viscous and kinetic dynamic relaxation methods in form-finding of membrane structures

  • Labbafi, S. Fatemeh;Sarafrazi, S. Reza;Kang, Thomas H.K.
    • Advances in Computational Design
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    • v.2 no.1
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    • pp.71-87
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    • 2017
  • This study focuses on the efficiency and applicability of dynamic relaxation methods in form-finding of membrane structures. Membrane structures have large deformations that require complex nonlinear analysis. The first step of analysis of these structures is the form-finding process including a geometrically nonlinear analysis. Several numerical methods for form-finding have been introduced such as the dynamic relaxation, force density method, particle spring systems and the updated reference strategy. In the present study, dynamic relaxation method (DRM) is investigated. The dynamic relaxation method is an iterative process that is used for the static equilibrium analysis of geometrically nonlinear problems. Five different examples are used in this paper. To achieve the grading of the different dynamic relaxation methods in form-finding of membrane structures, a performance index is introduced. The results indicate that viscous damping methods show better performance than kinetic damping in finding the shapes of membrane structures.

A Study on The Cutting Pattern Generation of Membrane Structures and Loss Ratio of Febrics According to the Curvature (막구조물의 재단도 작성과 곡률 변화에 따른 손실률에 관한 연구)

  • Jeon, Jin-Hyung;Jeong, Eul-Seok;Shon, Su-Deok;Kim, Seung-Deog
    • Proceeding of KASS Symposium
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    • pp.205-213
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    • 2006
  • Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cutting pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cooing pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cutting pattern generation using geodesic line, and investigate the result of example's cutting pattern in detail.

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A Study on The Search of Geodesic Line and Cuting Pattern Generation of Membrane Structures (막 구조물의 측지선 탐색과 재단도 작성에 관한 연구)

  • Jeon Jin-Hyung;Jeong Eul-Seok;Shon Su-Deok;Kim Seung-Deog
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.325-332
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    • 2006
  • Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cutting pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cutting pattern generation using geodesic line, and investigate the result of example's cutting pattern in detail.

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A Study on the Stress Concentration at Crack of Membrane Structures (막구조물의 파손단면에서의 응력집중 현상에 관한 연구)

  • Jeon, Jin-Hyung;Jeong, Eul-Seok;Kim, Seung-Deog
    • Proceeding of KASS Symposium
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    • pp.89-98
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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. Therefore membrane structures arc unstable structures initially. These soft structures need to be introduced initial stresses first because of its initial unstable state, and it happens large deformation phenomenon. To find the structural shape after large deformation caused by initial stiffness introduced, we need the shape analysis considering geometric nonlinearity in structural design procedure. In this study, we investigate into the stress concentration at crack of membrane structures. Therefore, using the nonlinear analysis program that NASS (Nonlinear Analysis for Spatial Structures) perform nonlinear analysis, and stress distribution for creak length investigate for using linear elastic fracture mechanics.

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

  • Ahn, Sang-Gil;Shon, Su-Deok;Kim, Seung-Deog
    • Proceeding of KASS Symposium
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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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Nonlinear wind-induced instability of orthotropic plane membrane structures

  • Liu, Changjiang;Ji, Feng;Zheng, Zhoulian;Wu, Yuyou;Guo, Jianjun
    • Wind and Structures
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    • v.25 no.5
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    • pp.415-432
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    • 2017
  • The nonlinear aerodynamic instability of a tensioned plane orthotropic membrane structure is theoretically investigated in this paper. The interaction governing equation of wind-structure coupling is established by the Von $K\acute{a}rm\acute{a}n's$ large amplitude theory and the D'Alembert's principle. The aerodynamic force is determined by the potential flow theory of fluid mechanics and the thin airfoil theory of aerodynamics. Then the interaction governing equation is transformed into a second order nonlinear differential equation with constant coefficients by the Bubnov-Galerkin method. The critical wind velocity is obtained by judging the stability of the second order nonlinear differential equation. From the analysis of examples, we can conclude that it's of great significance to consider the orthotropy and geometrical nonlinearity to prevent the aerodynamic instability of plane membrane structures; we should comprehensively consider the effects of various factors on the design of plane membrane structures; and the formula of critical wind velocity obtained in this paper provides a more accurate theoretical solution for the aerodynamic stability of the plane membrane structures than the previous studies.

Study on Dynamic Instability of Plane Membrane Structures under Wind Action (풍하중을 받는 평면 막구조물의 동적불안정 판정에 관한 연구)

  • Han, Sung-Eul;Hou, Xiao-Wu
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.2
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    • pp.145-152
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    • 2009
  • In this paper, dynamic instability of plane membrane structures under wind action has been studied. The key to solving the governing equations of membrane structures under wind action is how to obtain the air pressure on membrane. Based on Bernoulli's theorem, fluid pressure has a certain relationship with velocity potential. Velocity potential could be solved according to thin aerofoil theory, where air around the membrane is regarded as a sheet of vortices. In this paper, we take advantage of the most commonly used three-node triangular membrane element and weighted residual-Galerkin method to obtain the determining equation for stability evaluation. Square and rectangular membrane structures are studied. The influence of initial prestressing force and wind direction towards critical wind velocity are also analyzed in this paper.

Analysis Method for Cable-Membrane Structures with Element Slipping (외력에 의해 요소이동이 발생되는 케이블-막 구조물의 해석 방법)

  • Kang, Joo-Won;Kim, Jae-Yeol
    • Journal of Korean Association for Spatial Structures
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    • v.5 no.4
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    • pp.79-90
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    • 2005
  • The purpose of this study is development of a finite element algorithm to find out the stressed condition, slipped direction and slipped dimension when some elements of cable-membrane structures are slipped from it's initially designed coordinates by external loads as wind or non uniform load and so on. In order to search the slipped behaviors of cable-membrane structures, a Arbitrarily-Lagrangian-Eulerian(ALE) finite element formulation is introduced. In these procedures, a stiffness matrix related with ALE concept is formulated and a FE analysis program for cable-membrane structures with slipped elements is developed. Various examples for cable and membrane structures are presented to verify the program's validation. The results are shown good agreement with that of existed one.

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An Experimental Study on Biaxial Tensile Characteristics of ETFE Film and Stress Relaxation of Tension Typed Membrane Structures (ETFE 필름의 2축 인장특성 및 텐션방식 막구조물의 응력완화 거동에 관한 실험적 연구)

  • Kim, Seung-Deog;Jeong, Eul-Seok;Kawabata, Masaya
    • Journal of Korean Association for Spatial Structures
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    • v.16 no.1
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    • pp.35-42
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    • 2016
  • Until recently, almost all ETFE film structures that have been erected is the cushion type because there are problems at lower allowable strength under elastic range and viscosity behaviour such as creep and relaxation of ETFE films under long-term stresses. But the number of tension type structures is currently increasing. This paper proposes the stretch fabrication of ETFE film to verify the applicability of ETFE films to tensile membrane structures. First of all, to investigate the possibility of application on tensile membrane structures, the stretch fabrication test is carried out, and it is verified that it is possible to increase the yield strength of the film membrane structures. After simulating the experiment also carries out an analytical investigation, and the effectiveness of the elasto-plastic analysis considering the viscous behavior of the film is investigated. Finally, post-aging tension measurement is conducted at the experimental facilities, and the viscosity behavior resulting from relaxation is investigated with respect to tensile membrane structures.

A Study on The Cutting Pattern Generation of Membrane Structures and The Loss-Ratio of Material (막 구조물의 재단도 작성과 막재의 손실률에 관한 연구)

  • Shon, Su-Deok;Jeong, Eul-Seok;Kim, Seung-Deog
    • Journal of Korean Association for Spatial Structures
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    • v.6 no.1
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    • pp.117-127
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    • 2006
  • Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cooing pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cooing pattern generation using geodesic line, and investigate the result of example's cooing pattern in detail.

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