• Title, Summary, Keyword: 형상 최적설계

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Optimal Shape of LCVA considering Constraints on Liquid Level (수위의 구속조건을 고려한 LCVA의 최적형상)

  • Park, Ji-Hun;Kim, Gi-Myun;Lee, Sung-Kyung;Min, Kyung-Won
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.5
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    • pp.429-437
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    • 2009
  • This study addresses the optimal shape of a LCVA maximizing its vibration control effect through numerical parametric study. Various LCVAs having the same total mass and tuning frequency are designed with constraints on the dimensions and water level, and one obtaining the highest equivalent damping ratio of the controlled system is chosen as an optimal solution. As a result, it was found that the limit on the variation of the water level in the vertical liquid column plays an important role constraining the shape of the LCVA. As the LCVA width perpendicular to the plane of liquid motion increases, the equivalent damping ratio rises with slowdown so that determination of the proper width is important in design of the LCVA shape.

Optimal Design of Impeller according to Blade Shape Variation Using CFD Simulation (CFD를 이용한 블레이드 형상 변화에 따른 블로워 임펠러 최적설계)

  • Yu, Da-Mi;Kim, Semo;Jang, Hye-Lim;Han, Dae-Hyun;Kang, Lae-Hyong
    • Journal of Aerospace System Engineering
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    • v.13 no.1
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    • pp.29-37
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    • 2019
  • The objective of this study was to investigate the influence of the blade shape on the impeller performance, for design optimizing of the high airflow impeller. First, the quantity, angle, and length of blades, which are considered to have a large influence on the impeller performance, were selected as design variables. Then, 27 cases of impeller shapes were selected according to the design of experiment (DOE). To predict the conduct of the blower based on the selected impeller shape, flow analysis was performed using the immersed solid method of ANSYS CFX. In the CFD results, the highest airflow was expected in the impeller having a combination of 50 EA, $6^{\circ}$ and 5 mm. Finally, a blower with the original impeller shape and the optimized impeller shape was fabricated using a 3D printer, and the analysis tendency and experimental tendency were verified through experiments.

Maximization of the natural frequency of a structure using shape optimization (형상 최적화를 통한 구조물의 고유진동수 최대화)

  • 서범석;박윤식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.167-172
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    • 2001
  • 구조최적화는 기계구조물의 동특성을 변경하기 위하여 필수적으로 수행되어야 할 요소이다. 어떠한 방법을 택하여 보다 효율적으로 수행할 것 인지가 엔지니어의 관심일 것이다. 구조최적화는 설계변수에 따라 치수최적화, 물성치최적화 형상최적화 등으로 나눌 수 있다. 형상 최적화는 구조물의 유한요소모델을 기본으로 경계의 형상이나 절점의 형상, 회전 등을 설계 변수로 삼는 것이다. 고유진동수를 높이거나 모드형상을 제어하기 위하여 평판에 보강재를 붙이는 경우가 있다. 이때 보강재의 위치나 치수 형상 등이 중요한 변수가 될 수 있다. 본 논문에서는 평판의 고유진동수를 극대화 하기위해 보 보강재를 붙이는 문제에서 보의 회전을 설계 변수로 삼아 최적설계를 수행 할 것이다.

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Multi-Point Design Optimization of 5MW HAWT Blade (5MW급 수평축 풍력발전 블레이드의 다점 최적설계)

  • Park, Kyung-Hyun;Jun, Sang-Ook;Kim, Sang-Hun;Jung, Ji-Hun;Lee, Ki-Hak;Jeon, Yong-Hee;Choi, Dong-Hoon;Lee, Dong-Ho
    • 한국신재생에너지학회:학술대회논문집
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    • pp.474-477
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    • 2009
  • 본 연구에서는 5MW급 수평축 풍력발전 블레이드에 대한 정격풍속과 낮은 풍속 영역을 고려하여 풍속에 대한 다점 최적설계를 수행하였다. 다점 최적설계를 수행하기 위해 블레이드 해석은 Blade Element and Momentum theory를 이용 하였으며, 설계 시 적용된 기저형상은 NREL에서 제안한 5MW급 풍력터빈 블레이드이다. 최적화 과정을 통해 얻어진 최적해의 집합에 대하여 L2 Norm을 통한 파레토분석을 하였으며, 이를 통해 기저형상의 연간 에너지생산량과 설비 이용률을 보다 향상 시킬 수 있었다.

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Shape Design Optimization of Crack Propagation Problems Using Meshfree Methods (무요소법을 이용한 균열진전 문제의 형상 최적설계)

  • Kim, Jae-Hyun;Ha, Seung-Hyun;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.5
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    • pp.337-343
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    • 2014
  • This paper presents a continuum-based shape design sensitivity analysis(DSA) method for crack propagation problems using a reproducing kernel method(RKM), which facilitates the remeshing problem required for finite element analysis(FEA) and provides the higher order shape functions by increasing the continuity of the kernel functions. A linear elasticity is considered to obtain the required stress field around the crack tip for the evaluation of J-integral. The sensitivity of displacement field and stress intensity factor(SIF) with respect to shape design variables are derived using a material derivative approach. For efficient computation of design sensitivity, an adjoint variable method is employed tather than the direct differentiation method. Through numerical examples, The mesh-free and the DSA methods show excellent agreement with finite difference results. The DSA results are further extended to a shape optimization of crack propagation problems to control the propagation path.

A Study on Shape Optimum Design for Stability of Elastic Structures (탄성 구조물의 안정성을 고려한 형상최적설계)

  • Yang, Wook-Jin;Choi, Joo-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.1
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    • pp.75-82
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    • 2007
  • This paper addresses a method for shape optimization of a continuous elastic body considering stability, i.e., buckling behavior. The sensitivity formula for critical load is analytically derived and expressed in terms of shape variation, based on the continuum formulation of the stability problem. Unlike the conventional finite difference method (FDM), this method is efficient in that only a couple of analyses are required regardless of the number of design parameters. Commercial software such as ANSYS can be employed since the method requires only the result of the analysis in computation of the sensitivity. Though the buckling problem is more efficiently solved by structural elements such as a beam and shell, elastic solids have been chosen for the buckling analysis because solid elements can generally be used for any kind of structure whether it is thick or thin. Sensitivity is then computed by using the mathematical package MATLAB with the initial stress and buckling analysis of ANSYS. Several problems we chosen in order to illustrate the efficiency of the presented method. They are applied to the shape optimization problems to minimize weight under allowed critical loads and to maximize critical loads under same volume.

Level Set Based Shape Optimization of Linear Structures using Topological Derivatives (위상민감도를 이용한 선형구조물의 레벨셋 기반 형상 최적설계)

  • Yoon, Minho;Ha, Seung-Hyun;Kim, Min-Geun;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.1
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    • pp.9-16
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    • 2014
  • Using a level set method and topological derivatives, a topological shape optimization method that is independent of an initial design is developed for linearly elastic structures. In the level set method, the initial domain is kept fixed and its boundary is represented by an implicit moving boundary embedded in the level set function, which facilitates to handle complicated topological shape changes. The "Hamilton-Jacobi(H-J)" equation and computationally robust numerical technique of "up-wind scheme" lead the initial implicit boundary to an optimal one according to the normal velocity field while minimizing the objective function of compliance and satisfying the constraint of allowable volume. Based on the asymptotic regularization concept, the topological derivative is considered as the limit of shape derivative as the radius of hole approaches to zero. The required velocity field to update the H-J equation is determined from the descent direction of Lagrangian derived from optimality conditions. It turns out that the initial holes are not required to get the optimal result since the developed method can create holes whenever and wherever necessary using indicators obtained from the topological derivatives. It is demonstrated that the proper choice of control parameters for nucleation is crucial for efficient optimization process.

A Study on the Techniques of Configuration Optimization (형상 최적설계를 위한 최적화 기법에 관한 연구)

  • Choi, Byoung Han
    • Journal of Korean Society of Steel Construction
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    • v.16 no.6
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    • pp.819-832
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    • 2004
  • This study describes an efficient and facile method for configuration optimum design of structures. One of the ways to achieve numerical shape representation and the selection of design variables is using the design element concept. Using this technique, the number of design variables could be drastically reduced. Isoparametric mapping was utilized to automatically generate the finite element mesh during the optimization process, and this made it possible to easily calculate the derivatives of the coordinates of generated finite element nodes w.r.t. the design variables. For the structural analysis, finite element analysis was adopted in the optimization procedure, and two different techniques(the deterministic method, a modified method of feasible direction; and the stochastic method, a genetic algorithms) were applied to obtain the minimum volumes and section areas for an efficient configuration optimization procedure. Futhermore, spline interpolation was introduced to present a realistic optimum configuration that meet the manufacturing requirements. According to the results of several numerical examples(steel structures), the two techniques suggested in this study simplified the process of configuration optimum design of structures, and yielded improved objective function values with a robust convergence rate. This study's applicability and capability have therefore been demonstrated.

Unified Section and Shape Discrete Optimum Design of Planar and Spacial Steel Structures Considering Nonlinear Behavior Using Improved Fuzzy-Genetic Algorithms (개선된 퍼지-유전자알고리즘에 의한 비선형거동을 고려한 평면 및 입체 강구조물의 통합 단면, 형상 이산화 최적설계)

  • Park, Choon Wook;Kang, Moon Myung;Yun, Young Mook
    • Journal of Korean Society of Steel Construction
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    • v.17 no.4
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    • pp.385-394
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    • 2005
  • In this paper, a discrete optimum design program was developed using the refined fuzzy-genetic algorithms based on the genetic algorithms and the fuzzy theory. The optimum design in this study can perform section and shape optimization simultaneously for planar and spatial steel structures. In this paper, the objective function is the weight of steel structures and the constraints are the design limits defined by the design and buckling strengths, displacements, and thicknesses of the member sections. The design variables are the dimensions and coordinates of the steel sections. Design examples are given to show the applicability of the discrete optimum design using the improved fuzzy-genetic algorithms in this study.

The CAE technology of automobile die for optimal design (자동차 금형의 최적설계를 위한 CAE 기술)

  • 김영석
    • Journal of the korean Society of Automotive Engineers
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    • v.17 no.2
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    • pp.24-34
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    • 1995
  • 여기서는 최근의 자동차 금형의 최적설계 기술개발을 위한 국내의 연구동향을 중심으로 살펴보고 실제 CAE 기술의 적용 예를 소개하고자 한다. 1. 금형설계에서의 CAE 기술의 도입. 2. CAE 기술로서의 FEA 해석. 3. CAE 도입의 기술적 제 문제. 4. 프레스 공정의 2차원/3차원 해석. 5. 최적 블랭크 형상설계기술. 6. 강건설계를 위한 CAE 기술의 응용.

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