• Title/Summary/Keyword: global-local analysis

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A New Global-Local Analysis Using MLS(Moving Least Square Variable-Node Finite Elements (이동최소제곱 다절점 유한요소를 이용한 새로운 전역-국부해석)

  • Lim, Jae-Hyuk;Im, Se-Young
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.3
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    • pp.293-301
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    • 2007
  • We present a new global-local analysis with the aid of MLS(Moving Least Square) variable-node finite elements which can possess an arbitrary number of nodes on element master domain. It enables us to connect one finite element with a few finite elements without complex remeshing. Compared to other type global-local analysis, it does not require any superimposed mesh or need not solve the equilibrium equation twice. To demonstrate the performance of the proposed scheme, we will show several examples in relation to capturing highly local stress field using global-local analysis.

A new global/local analysis using MLS (Moving Least Square)-based finite elements (이동최소제곱 기반 유한요소를 이용한 새로운 다중 스케일 해석)

  • Lim, Jae-Hyuk;Im, Se-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.405-410
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    • 2007
  • We present a new global/local analysis with the aid of MLS(Moving Least Square)-based finite elements which can handle an arbitrary number of nodes on every element side. It give a great flexibility in constructing finite element meshes at the specified local regions without remeshing. Compared to other type global/local analysis, it does not require any superimposed mesh or need not solve the equilibrium equation twice as well as shows an excellent accuracy. To demonstrate the performance of proposed scheme, we will show several examples in relation to capturing highly local stress field.

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An Efficient Analysis of Wrinkling in the Door Inner Stamping Process by Global Analysis and Subsequent Local Analysis (전체해석과 국부해석을 통한 Door Inner 스탬핑 공정에서 발생하는 주름의 효과적인 해석)

  • 김종봉;김태정;양동열;유동진
    • Transactions of Materials Processing
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    • v.9 no.6
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    • pp.653-662
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    • 2000
  • Wrinkling is one of the major defects in sheet metal products together with tearing, springback and other geometric and surface defects. The initiation and growth of wrinkles are influenced by many factors such as stress ratios, mechanical properties of the sheet material, geometry of the workpiece, contact condition, etc. It is difficult to analyze the wrinkling initiation and growth considering all the factors because the effects of the factors are very complex and the wrinkling behavior may show a wide scatter of data even for small deviations of factors. The finite element analyses of the wrinkling initiation and growth in the sheet metal forming process provide the detailed information about the wrinkling behavior of sheet metal. The direct analyses of the wrinkling initiation and growth, however, bring about a little difficulty in complex industrial problems because it needs large memory size and long computation time. In the present study, therefore, a global-local analysis technique is introduced for the computational efficiency. Through the analysis of wrinkling in the door inner stamping process, the efficiency of the global-local analysis technique is investigated.

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Interface element method (IEM) for a partitioned system with non-matching interfaces (일치하지 않는 경계를 갖는 분리된 시스템을 위한 계면 요소법)

  • Kim, Hyun-Gyu
    • Proceedings of the KSME Conference
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    • pp.324-329
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    • 2001
  • A novel method for non-matching interfaces on the boundaries of the finite elements in partitioned domains is presented by introducing interface elements in this paper. The interface element method (IEM) satisfies the continuity conditions exactly through interfaces without recourse to the Lagrange multiplier technique. The moving least square (MLS) approximation in the present study is implemented to construct the shape functions of the interface elements. Alignment of the boundaries of sub-domains in the MLS approximation and integration domains provides a consistent numerical integration due to one form of rational functions in an integration domain. The compatibility of displacements on the boundaries of the finite elements and the interface elements is always preserved in this method, and the completeness of the shape functions of the interface elements guarantees the convergence of numerical solutions. The numerical examples show that the interface element method is a useful tool for the analysis of a partitioned system and for a global-local analysis.

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Evaluation of sloshing resistance performance for LNG carrier insulation system based on fluid-structure interaction analysis

  • Lee, Chi-Seung;Cho, Jin-Rae;Kim, Wha-Soo;Noh, Byeong-Jae;Kim, Myung-Hyun;Lee, Jae-Myung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.1
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    • pp.1-20
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    • 2013
  • In the present paper, the sloshing resistance performance of a huge-size LNG carrier's insulation system is evaluated by the fluid-structure interaction (FSI) analysis. To do this, the global-local analysis which is based on the arbitrary Lagrangian-Eulerian (ALE) method is adopted to accurately calculate the structural behavior induced by internal LNG sloshing of a KC-1 type LNG carrier insulation system. During the global analysis, the sloshing flow and hydrodynamic pressure of internal LNG are analyzed by postulating the flexible insulation system as a rigid body. In addition, during the local analysis, the local hydroelastic response of the LNG carrier insulation system is computed by solving the local hydroelastic model where the entire and flexible insulation system is adopted and the numerical analysis results of the global analysis such as initial and boundary conditions are implemented into the local finite element model. The proposed novel analysis techniques can potentially be used to evaluate the structural integrity of LNG carrier insulation systems.

Development of three dimensional variable-node elements and their applications to multiscale problems (삼차원 다절점 유한요소의 개발과 멀티스케일 문제의 적용)

  • Lim, Jae-Hyuk;Sohn, Dong-Woo;Im, Se-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.172-176
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    • 2008
  • In this paper, three dimensional linear conforming variable-finite elements are presented with the aid of a smoothed integration (a class of stabilized conforming nodal integration), for mnltiscale mechanics problems. These elements meet the desirable properties of an interpolation such as the Kronecker delta condition, the partition of unity condition and the positiveness of interpolation function. The necessary condition of linear exactness is fully relaxed by employing the smoothed integration, which renders us to meet the linear exactness in a straightforward manner. This novel element description extend the category of the conventional finite elements space to ration type function space and give the flexibility on the number of nodes of element which are fixed in the conventional finite elements. Several examples are provided to show the convergence and the accuracy of the proposed elements, and to demonstrate their potential with emphasis on the multiscale mechanics problems such as global/local analysis, nonmatching contact problems, and modeling of composite material with defects.

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HYDROPLANING ANALYSIS BY FEM AND FVM - EFFECT OF TIRE ROLLING AND TIRE PATTERN ON HYDROPLANING

  • Nakajima, Y.;Seta, E.;Kamegawa, T.;Ogawa, H.
    • International Journal of Automotive Technology
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    • v.1 no.1
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    • pp.26-34
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    • 2000
  • The new numerical procedure for hydroplaning has been developed by considering the following three important factors; fluid/structure interaction, tire rolling, and practical tread pattern. The tire was analyzed by FEM with Lagrangian formulation and the fluid is analyzed by FVM with Eulerian formulation. Since the tire and the fluid are modeled separately and their coupling is automatically computed by the coupling element, the fluid/structure interaction of the complex geometry such as the tire with the tread pattern can be analyzed practically. We verified the predictability of the hydroplaning simulation in the different parameters such as the water flow, the velocity dependence of hydroplaning, and the effect of the tread pattern on hydroplaning. In order to predict the streamline in the contact patch, the procedure of the global-local analysis was developed. Since the streamline could be predicted by this technology, we could develop the new pattern in a short period based on the principle; "make the stream line smooth".

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Evaluation of sloshing Resistance Performance of LNG Carrier Insulation System by Fluid-Structure Interaction Analysis (유체-구조 연성 해석을 이용한 LNG 운반선 방열시스템의 내슬로싱 성능 평가)

  • Lee, Chi-Seung;Kim, Joo-Hyun;Kim, Wha-Soo;Noh, Byeong-Jae;Kim, Myung-Hyun;Lee, Jae-Myung
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.557-560
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    • 2011
  • In the present paper, the sloshing resistance performance of an LNG carrier insulation system is evaluated by fluid-structure interaction (FSI) analysis. For this analysis, the arbitrary Lagrangian Eulerian (ALE) method is adopted to accurately calculate the structural behavior induced by internal LNG motion of a KC-1 type LNG carrier cargo tank. In addition, the global-local analysis method is introduced to reduce computational time and cost. The global model is built from shell elements to reduce the sloshing analysis time. The proposed novel analysis techniques can potentially be used to evaluate the structural integrity of LNG carrier insulation systems.

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Iterative global-local procedure for the analysis of thin-walled composite laminates

  • Afnani, Ashkan;Erkmen, R. Emre
    • Steel and Composite Structures
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    • v.20 no.3
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    • pp.693-718
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    • 2016
  • This paper presents a finite element procedure based on Bridging multi-scale method (BMM) in order to incorporate the effect of local/cross-sectional deformations (e.g., flange local buckling and web crippling) on the global behaviour of thin-walled members made of fibre-reinforced polymer composite laminates. This method allows the application of local shell elements in critical regions of an existing beam-type model. Therefore, it obviates the need for using computationally expensive shell elements in the whole domain of the structure, which is otherwise necessary to capture the effect of the localized behaviour. Consequently, highly accurate analysis results can be achieved with this method by using significantly smaller finite element model, compared to the existing methods. The proposed method can be used for composite polymer laminates with arbitrary fibre orientation directions in different layers of the material, and under various loading conditions. Comparison with full shell-type finite element analysis results are made in order to illustrate the efficiency and accuracy of the proposed technique.