• Title, Summary, Keyword: initial shape analysis

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Comparison Study of An Improved Initial Force and TCUD Method for Initial Shape Analysis of Cable-Stayed Bridges (사장교의 초기형상해석을 위한 개선된 초기부재력법 및 TCUD법의 비교연구)

  • Kim, Dong-Yeong;Jo, Kyeong-Sik;Kim, Moon-Young
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.1
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    • pp.101-108
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    • 2012
  • Initial shape analysis for cable-stayed bridges should be able to find optimizated initial cable forces and unstrained length that minimize deflection and bending moments of the deck and pylon. Comparison study of an improved initial force method and TCUD method for determination of initial cable forces in cable-stayed bridges is presented in this paper. For this purpose, an elastic catenary cable element and a nonlinear frame element are firstly described. And concepts and algorithm of two analysis methods are then presented. Finally to demonstrate the validity and the accuracy of two methods, numerical examples for initial state problems of cable-stayed bridges are given and compared based on these methods.

A Study on the Cutting Pattern Determination for Fabric Structures (막 구조물의 재단 패턴 결정에 관한 연구)

  • Choi, Ho;Lee, Jang-Bog;Kim, Jae-Yeol;Sur, Sam-Uel;Kwon, Taek-Jin
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.266-273
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    • 1998
  • The object of this study is shape finding and cutting pattern generation of membrane structures under the following assumptions: (1) material is linearly elastic (2) stress state is plane stress. Cable and membrane structures should introduce the nonlinear analysis considering geometric nonlinearity because these structures deform largely under the external loads. The analysis procedure is consisted of three steps considering geometric nonlinearity unlike any other structures. First step is the shape finding analysis to determine the initial equilibrium shape. Second step is the stress-deformation analysis to investigate the behaviors of structures under various external loads. Once a satisfactory shape has been found, a cutting pattern based on the shape finding analysis may be generated from the view point of construction. In this paper, after shape finding analysis, cutting pattern determination procedure using weighted least-square minimization flattening method and some results are presented.

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Behavior of Tapered Columns with Initial Imperfection (Initial Imperfection을 갖는 변단면 기둥의 거동 해석)

  • 이병구;모정만
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.19-26
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    • 1996
  • The main purpose of this paper is to investigate a more accurate behavior analysis of tapered column with initial imperfection. The nonlinear differential equations governing the deflected shapes of the tapered column with initial imperfection are derived by large deflection theory and solved numerically using the Runge-Kutta method and Regula-Falsi method. Three kinds of cross-sectional shape with simply supported end constraint are considered in numerical examples. The load versus displacement curves including the left and right end rotations are presented in figures. The effect of cross-sectional shapes on deflected shape is analyzed, and the deflected shapes of column for several initial imperfections are shown in figure.

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A Study on the Nonlinear Structural Analysis of Barrel Vault-Typed Membrane Roof Structures Considering the Orthotropic Material (직교이방성을 고려한 Barrel Vault형 지붕 막구조물의 비선형 구조해석에 관한 연구)

  • Kim, Seung-Deog;Jeong, Eul-Seok;Baek, In-Seong
    • Journal of the Korean Association for Spatial Structures
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    • v.5 no.1
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    • pp.91-98
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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 are 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 analyze the soft spatial structures by the NASS which is the program for nonlinear analysis. The analytic model is a roof membrane structures of Barrel Vault-Type. We have done the shape analysis and the stress-deformation analysis considering the orthotropic material, and then study the safety.

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Statistical Analysis for Fatigue Lifetime of Ceramics (세라믹스의 피로수명에 대한 통계적 분석)

  • 박성은;김성욱;이홍림
    • Journal of the Korean Ceramic Society
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    • v.34 no.9
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    • pp.927-934
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    • 1997
  • Static and cyclic fatigue tests were carried out for alumina specimen to study the statistical analyses (normal, lognormal and Weibull distribution) of fatigue lifetime data and nominal initial crack length data. Fatigue lifetime data followed Weibull distribution better than normal or lognormal distribution, for the shape parameter of the notched specimen was larger than that of the unnotched specimen. The nominal initial crack length data obtained from fatigue lifetime followed the lognormal and Weibull distribution better than normal distribution, for the coefficient of variation of the unnotched specimen was larger than that of the notched specimen, and shape parameter of unnotched specimen was smaller than that of the notched specimen.

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Experimental and analytical study of steel slit shear wall

  • Khatamirad, Milad;Shariatmadar, Hashem
    • Steel and Composite Structures
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    • v.24 no.6
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    • pp.741-751
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    • 2017
  • A steel slit shear wall has vertical slits and when it is under lateral loads, the section between these slits has double-curvature deformation, and by forming a flexural plastic hinge at the end of the slit, it dissipates the energy on the structure. In this article, Experimental, numerical and analytical analyses are performed to study the effect of slit shape and edge stiffener on the behavior of steel slit shear wall. Seismic behavior of three models with different slit shapes and two models with different edge stiffener shapes are studied and compared. Hysteresis curves, energy dissipation, out of plane buckling, initial stiffness and strength are discussed and studied. The proposed slit shape reduces the initial stiffness, increases the strength and energy dissipation. Also, edge stiffener shape increases the initial stiffness significantly.

Blank Design System for Sheet Forming (박판성형의 초기소재 설계시스템)

  • 김두현;이정민;박상후;양동열;김용환
    • Transactions of Materials Processing
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    • v.6 no.5
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    • pp.400-407
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    • 1997
  • Geometric mapping technique has been used to find the shape of initial blank for sheet forming. The method was chosen because of its simplicity and numerical efficiency. Error in blank shape were measured along deformation path by FE analysis of forming. Blank shape was modified by volume additionaddition/Subtractiontraction method with taking with taking into account of deformation path. Modified blank shape shows an acceptable result, showing the current method can be an useful tool for predicting blank shape in the practical application. More test will be done to verify the validity of the method.

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Numerical Simulation of Double SMA wire Actuator Using Two-Way Shape Memory Effect of SMA (형상기억합금의 양방향효과를 이용한 두개의 형상기억합금선이 부착된 작동기의 수치해석)

  • Kim, Sang-Haun;Cho, Maeng-Hyo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.287-290
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    • 2004
  • A structure using the two-way shape memory effect (TWSME) returns to its initial shape by increasing or decreasing temperature under initial residual stress. Through the thermo-mechanical constitutive equation of shape memory alloy(SMA) proposed by Lagoudas et al., we simulate the behavior of a double actuator in which two SMA wires are attached to the tip of panel under the initially given residual stress. Through the numerical results conducted in the present study, the proposed actuator device is suitable for repeated actuation. The simulation algorithm proposed in the present study can be applied extensively to the analysis of the assembled .system of SMA-actuator and host structure in the practical applications.

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A Study on the Optimal Preform Shape Design using FEM and Genetic Algorithm in Hot Forging (열간단조에서 유한요소법과 유전 알고리즘을 이용한 예비성형체의 최적형상 설계 연구)

  • Yeom, Sung-Ho;Lee, Jeong-Ho;Woo, Ho-Kil
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.4
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    • pp.29-35
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    • 2007
  • The main objective of this paper is to propose the optimal design method of forging process using genetic algorithm. Design optimization of forging process was doing about one stage and multi stage. The objective function is considered the filling of die. The chosen design variables are die geometry in multi stage and initial billet shape in one stage. We performed FE analysis to simulated forging process. The optimized preform and initial billet shape was obtained by genetic algorithm and FE analysis. To show the efficiency of GA method in forging problem are solved and compared with published results.

Development of Intermediate Die Shape Design Program for Multi-Pass Shape Drawing by Using VisualLISP (VisualLISP을 이용한 다단이형인발 중간패스 단면형상설계 프로그램 개발)

  • Lee, S.K.;Lee, S.B.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.19 no.4
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    • pp.242-247
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    • 2010
  • In the multi-pass shape drawing process, it is important to design the intermediate dies for producing sound products. Up to now, the design of the intermediate dies is mainly carried out by the industrial experts based on their experience. In this study, a design program was developed to design the intermediate dies for multi-pass shape drawing process. The program was programmed by using VisualLISP. In this program the intermediate dies can be designed by using the initial material shape and the final product shape. In order to verify the effectiveness, the program was applied to design the intermediate dies of multi-pass shape drawing for producing four teeth spline and gun slide. Finally, FE analysis and shape drawing experiment were performed to verify the effectiveness of the designed intermediate dies. As a result, it was possible to produce the drawn products with the required dimensional accuracy.