• Title/Summary/Keyword: Element Connectivity

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Topology Optimization Using the Element Connectivity Parameterization Method in Three Dimensional Design Domain (3차원 설계 영역에서의 요소 연결 매개법을 이용한 위상 최적 설계)

  • Ho Yoon Gil;Young Kim Yoon;Soo Joung Yuung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.7 s.238
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    • pp.990-997
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    • 2005
  • The objective of this paper is to present the element connectivity parameterization (ECP) fur three dimensional problems. In the ECP method, a continuum structure is viewed as discretized finite elements connected by zero-length elastic links whose stiffness values control the degree of inter-element connectivity. The ECP method can effectively avoid the formation of the low-density unstable elements. These elements appear when the standard element density method is used for geometrical nonlinear problems. In this paper, this ECP method developed fur two-dimensional problems is expanded to the design of three-dimensional geometrical nonlinear structures. Among others, the automatic procedure converting standard finite element models to the models suitable for the ECP approach is developed and applied for optimization problems defined on general three-dimensional design domains.

Element Connectivity Based Topology Optimization for Linear Dynamic Compliance (요소 연결 매개법을 이용한 선형 구조물의 동적 컴플라이언스 최적화)

  • Yoon, Gil-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.3
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    • pp.259-265
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    • 2009
  • This paper studies the Element Connectivity Parameterization Method(ECP method) for topology optimization considering dynamic compliance. The previous element density based topology optimization method interpolates Young's modulus with respect to design variables defined in each element for topology optimization. Despite its various applications, these element density based methods suffer from numerical instabilities for nonlinear structure and multiphysics systems. To resolve these instabilities, recently a new numerical method called the Element Connectivity Parameterization(ECP) Method was proposed. Unlike the existing design methods, the ECP method optimizes the connectivities among plane or solid elements and it shows some advantages in topology optimization for both nonlinear structure and multiphysics systems. In this study, the method was expanded for topology optimization for the dynamic compliance by developing a way to model the mass matrix in the framework of the ECP method.

Topology Optimization of Geometrically Nonlinear Structure Considering Load-Displacement Trajectory (하중-변위 관계를 고려한 기하 비선형 구조물의 위상 최적 설계)

  • Noh, Jin-Yee;Yoon, Gil-Ho;Kim, Yoon-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.8
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    • pp.779-785
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    • 2009
  • This paper is concerned with a computational approach for topology optimization of geometrically nonlinear structures following specific load-displacement trajectories. In our previous works, attention was paid to stabilize topology optimization involving large displacement and a method called the element connectivity parameterization was developed. Here, we aimed to extend the element connectivity parameterization method to find an optimal geometrically nonlinear structure yielding a specific load-displacement trajectory. In contrast to designing a stiffest structure, the trajectory design problem requires special consideration in topology optimization formulation and solution procedure. Some numerical problems were considered to test the developed element connectivity parameterization based formulation.

Optimal Design of Nonlinear Coupled Multiphysics Structural Systems using The Element Connectivity Parameterization (복합 물리 시스템 위상 최적설계를 위한 요소 연결 매개법)

  • Yoon, Gil-Ho;Kim, Yoon-Young
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1017-1022
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    • 2004
  • Though the standard element density-based topology optimization method has been applied for the optimal design of multiphysics systems, some theoretical problems, such as material interpolation, undershoot temperature prediction, and unstable elements, still remain to be overcome. The objective of this investigation is to present a new topology optimization formulation based on the element connectivity parameterization (ECP) in order to avoid the numerical problems in multiphysics system design and improve optimization results. To show the validity of the proposed approach, the designs of an optimal thermal dissipation and an electro-thermal-compliant actuator were considered.

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The Evaluation of Connectivity between Natural Environment (Forests and Rivers) and Neighborhood Parks Inside Cities in Gyeonggi-do (도시 내 자연환경(산림, 하천)과 근린공원의 연결 현황 평가 및 연결방안)

  • Sung, Hyun-Chan;Kim, Su-Ryeon;Kang, Da-In;Hwang, So-Young
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.18 no.5
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    • pp.49-59
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    • 2015
  • In this research, the connectivity status between natural environment (forests and rivers) and urban parks in view of ecological networks in a city is evaluated and on the basis of these evaluation results, a future connectivity enhancing recommendations are suggested. As a result, the 96.8% of the connectivity role of the neighborhood parks were core or connected parks and as in terms of the ecological pattern on the outer park, 84.1% of the case neighborhood parks were connected to the ecological element at least one side. Therefore, it can be expected to play a role as corridor that enables the direct connection with the natural environment if the connection plan is well established. As a result of connectivity evaluation of the parks, inside of the parks had low ecological element overall and had low connectivity, outside of the parks had 1.5 times more of low connectivity parks than high connectivity parks, and had similar disconnections such as facilities(fence, soundproof walls, breast walls, etc.), developments(roads, apartment complexes, industrial complexes, etc.), or poor greens regardless of the neighborhood with the ecological elements. To increase the connectivity of ecological network, the cities already built shall secure primarily green territory where can connect with the isolated park due to the surrounding with the developing areas and when planning for new cities or residential complexes, it shall establish a connection plan with the nearby at the beginning.

The Topology Optimization of Three-dimensional Cooling Fins by the Internal Element Connectivity Parameterization Method (내부 요소 연결 매개법을 활용한 3 차원 냉각핀의 위상 최적설계)

  • Yoo, Sung-Min;Kim, Yoon-Young
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.360-365
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    • 2007
  • This work is concerned with the topology optimization of three-dimensional cooling fins or heat sinks. Motivated by earlier success of the Internal Element Connectivity Method (I-ECP) method in two-dimensional problems, the extension of I-ECP to three-dimensional problems is carried out. The main efforts were made to maintain the numerical trouble-free characteristics of I-ECP for full three-dimensional problems; a serious numerical problem appearing in thermal topology optimization is erroneous temperature undershooting. The effectiveness of the present implementation was checked through the design optimization of three-dimensional fins.

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Maximizing Eigenfrequency of Geometrical Nonlinear Structure using Topology Optimization (위상최적화를 이용한 기하 비선형 구조물의 고유진동수 최적화)

  • Yoon, Gil-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2009.04a
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    • pp.89-92
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    • 2009
  • 본 논문에서는 비선형구조물의 위상최적화를 위하여 개발된 요소 연결 매개법 (Element Connectivity Parameterization Method)을 이용하여 기하비선형 구조물의 고유진동수(Eigenfrequency)를 최적화하는 연구를 소개한다. 기존의 밀도를 기반으로 한 위상최적화기법은 비선형 구조물의 위상최적화를 수행할 때 약한 탄성계수를 가지는 요소가 대변형을 일으켜 전체 강성행렬(Tangent Stiffness Matrix)이 양정정성(Positive definiteness)를 잃어버리는 문제점이 있어서 위상최적화를 수행하기 어렵다. 이 문제점을 해결하기 위하여 최근에 요소 연결 매개법(Element Connectivity Parameterization Method)이 개발되었다. 이 요소 연결 매개법은 요소의 강성을 설계하는 것이 아니라 요소의 연결성을 설계하는 기법으로 이를 이용하여 비선형 구조물의 위상최적화를 효과적으로 수행할 수 있다. 이 연구에서는 요소 연결 매개법을 동적인 문제에 적용하기 위한 연구를 수행하며 이를 이용하여 비선형 구조물의 고유진동수를 최적화 하는 위상최적화 문제에 적용하였다. 비선형 수치 예제를 통하여 기하 비선형 구조물의 고유진동수를 최대화를 통하여 기하 비선형 구조물의 강성최대화 문제와 같은 결과를 얻을 수 있었다.

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Development of an Algorithm for the Vision-Based Surface-Strain Measurment of Large Stamped Parts (비전을 이용한 중.대형 판재성형 제품의 곡면 변형률 측정 알고리듬 개발)

  • 김형종
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.269-272
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    • 1999
  • It is still hard to measure the strain distribution over entire surface of a medium or large-size stamped part even by using an automated strain measurement system. Several methods which enable to enlarge the measurement range without losing accuracy and precision are suggested in this study, The superposition of images having different high-lightened or damaged part each other results in an enhanced image. A new method for constructing the element connectivity from a line-thinned image makes it possible to identify up to 1,000 elements. And the geometry assembling algorithm is proved very efficient in which the whole area to be measured is divided into several parts ; the coordinate transformation between every two adjacent parts is obtained from the concept of the least square error ; and the 3-D shape or strain distribution over the whole surface is assembled,

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Modelling of Structural Adhesives for Body Stiffness Analysis in Automobile (차체 강성해석을 위한 구조용 접착제 해석모델링 연구)

  • Seo, Seong-Hoon;Joo, Jae-Kap
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1410-1414
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    • 2007
  • In modern automobile body manufacturing, the structural adhesive bonding is recognized to one of new joining techniques for the purpose of light weight body and its application scope in the automobile body has been gradually magnified. Specially, the structural adhesives have the advantages of not only enhancing the design flexibility of automobile body, but also improving automobile performances such as stiffness, crashworthiness and durability. In order to evaluate the performance simulation of the automobile body applied with structural adhesives, it is necessary to develop modeling techniques in the structural adhesives in advance. This paper aims to investigate modeling methodology of structural adhesive junctions for body stiffness simulation. Two main modeling points are the element selection for adhesives and the connectivity between adhesives and adherends. Both of the 1D element used in classical modeling and the 3D element which are more accurate are considered for the adhesives, and the congruent and incongruent mesh models of the adherends are compared for connectivity modeling. By applying the several kinds of modeling methodology to the simple structures, the simulation results are compared and some modeling guidelines are obtained.

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