• Title, Summary, Keyword: 형상 최적설계

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Topology Optimization in the Process of Conceptual Design (개념설계를 위한 토폴로지 최적화 기법)

  • 고병천
    • Journal of the KSME
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    • v.35 no.8
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    • pp.716-724
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    • 1995
  • 토폴로지 설계는 미리 형상이 결정되지 않은 새로운 개념의 제품을 설계하고자 할 때나 설계 경험이 풍부하지 못한 경우, 그 개념적 형상을 결정하는 데 매우 유용하다. 실제로 이러한 토폴 로지 설계의 결과를 최근 급속 시제품 제작기(rapid prototyping machine)와 함께 사용하게 되면 처음 개념설계에서 최초시제품의 형상을 예측하고 제작하는 데 많은 시간을 절약할 것으로 판 단된다. 그러나 토폴로지 최적화에 따른 구조물은 구조물의 한계 질량내에서 평균 강성이 가장 큰 구조물일 뿐, 국부적인 응력한계에 대한 최적화는 아니다. 따라서 최종적인 최적화 형상을 얻기 위해서는, 먼저 한계질량을 갖는 최적 토폴로지 구조물의 모델을 구하고, 이 모델에 대하여 설계변수에 따른 민감도 해석을 수행하여 최대응력의 한계값을 갖는 구조를 구하면 된다. 그림 10은 이러한 토폴로지 최적화와 민감도 해석을 통한 최적화를 수행하는 복합 최적설계 과정에 흐름도이다. 설계민감도 해석은 본 연구의 범위에 포함되지 않아서 여기서는 제외하였지만, 이에 관한 일반 상업화된 소프트웨어들이 많이 나와 있으므로 이를 참조하면 된다.

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Optimal Design of Deep-Sea Pressure Hulls using CAE tools (CAE 기법을 활용한 심해 내압구조물의 최적설계에 관한 연구)

  • Jeong, Han Koo;Henry, Panganiban
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.6
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    • pp.477-485
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    • 2012
  • Geometric configurations such as hull shape, wall thickness, stiffener layout, and type of construction materials are the key factors influencing the structural performance of pressure hulls. Traditional theoretical approach provides quick and acceptable solutions for the design of pressure hulls within specific geometric configuration and material. In this paper, alternative approaches that can be used to obtain optimal geometric shape, wall thickness, construction material configuration and stiffener layout of a pressure hull are presented. CAE(Computer Aided Engineering) based design optimization tools are utilized in order to obtain the required structural responses and optimal design parameters. Optimal elliptical meridional profile is determined for a cylindrical pressure hull design using metamodel-based optimization technique implemented in a fully-integrated parametric modeler-CAE platform in ANSYS. While the optimal composite laminate layup and the design of ring stiffener for a thin-walled pressure hull are obtained using gradient-based optimization method in OptiStruct. It is noted that the proposed alternative approaches are potentially effective for pressure hull design.

Optimum Shape Design of Gearbox Housing for 5MW Wind Turbines (5MW급 풍력발전기용 기어박스 하우징의 형상 최적설계)

  • Jeong, Ki-Yong;Lee, Dae-Yeon;Choi, Eun-Ho;Cho, Jin-Rea;Lim, O-Kaung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.3
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    • pp.237-243
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    • 2012
  • The thickness optimization of the gearbox housing for 5MW wind turbine is carried out with the help of the efficient structure analysis model and the approximation model of objective function. Wind turbine gearbox is a complex structural system composed of a number of gear trains, shafts, bearing and gearbox housing, requiring a tremendous number of elements for the structural analysis and design. In this paper, an effective analysis and design model considering the tooth stiffness of helical gears is proposed. It enables to significantly reduce the total element number and the analysis time. Through the numerical optimization of housing thickness making use of the effective gearbox model and the approximate model of objective function, the total weight of the gearbox housing is minimized. It has been observed from the numerical experiment that the approximation model is reliable and the optimization result is acceptable and verified analysis.

Level Set Based Topological Shape Optimization Combined with Meshfree Method (레벨셋과 무요소법을 결합한 위상 및 형상 최적설계)

  • Ahn, Seung-Ho;Ha, Seung-Hyun;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.1
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    • pp.1-8
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    • 2014
  • Using the level set and the meshfree methods, we develop a topological shape optimization method applied to linear elasticity problems. Design gradients are computed using an efficient adjoint design sensitivity analysis(DSA) method. The boundaries are represented by an implicit moving boundary(IMB) embedded in the level set function obtainable from the "Hamilton-Jacobi type" equation with the "Up-wind scheme". Then, using the implicit function, explicit boundaries are generated to obtain the response and sensitivity of the structures. Global nodal shape function derived on a basis of the reproducing kernel(RK) method is employed to discretize the displacement field in the governing continuum equation. Thus, the material points can be located everywhere in the continuum domain, which enables to generate the explicit boundaries and leads to a precise design result. The developed method defines a Lagrangian functional for the constrained optimization. It minimizes the compliance, satisfying the constraint of allowable volume through the variations of boundary. During the optimization, the velocity to integrate the Hamilton-Jacobi equation is obtained from the optimality condition for the Lagrangian functional. Compared with the conventional shape optimization method, the developed one can easily represent the topological shape variations.

Optimal Design of Gerotor with Combined Profiles (Three-Ellipse and Ellipse-Involute-Ellipse) Using Rotation and Translation Algorithm (회전이동 및 병진이동 알고리즘을 이용한 조합된 치형형상(3-타원 및 타원-인벌루트-타원)을 갖는 지로터의 최적설계)

  • Bae, Jun Ho;Lee, Ho Ryul;Kim, Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.2
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    • pp.169-177
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    • 2015
  • Because technology of the sintering process is highly advanced, the gerotor used in the internal gear pumps of vehicles has advantages for manufacturing complex profiles and obtaining durability and minimization. However, it has been necessary to continuously improve the flow rate and noise of internal gear pumps for better fuel efficiency. The existing rotor was designed using a translation algorithm. This caused a discontinuity of the rotor profile, which had adverse effects on the performance. In this study, to improve the discontinuity of the profile, a new design program using a rotation and translation algorithm was developed, and two types of combined multiple profiles (three-ellipses and ellipse 1-involute-ellipse 2) were generated. Then, the performances (flow, flow rate, specific sliding, and pressure angle) of these profiles were calculated. On the basis of the calculation results for the performances, optimal designs of the two types were carried out and verified by comparing their performances with those of the existing rotor profiles.

Design Optimization of Moving-Coil Type Linear Actuator Using Level Set Method and Phase-Field Model (레벨셋법과 페이즈 필드 모델을 이용한 가동코일형 리니어 액추에이터 최적설계)

  • Lim, Sung-Hoon;Oh, Se-Ahn;Min, Seung-Jae;Hong, Jung-Pyo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.10
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    • pp.1223-1228
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    • 2011
  • A moving-coil type linear actuator has been widely used in the system reciprocating short stroke because of its several advantages, such as the structural simplicity, low weight and a fast control response speed. This paper presents a design approach for improving the actuating performance with a clear expression of optimal configuration represented by a level set function. The optimization problem is formulated to minimize the variation of magnetic force at every moving displacement of the mover for fast and easy control. To consider the manufacturability of actuator, the concept of phase-field model is incorporated to control the complexity of structural boundaries. To verify the usefulness of the proposed method, the core design example of cylindrical linear actuator is performed.

Shape optimal design of a dust cover for ball joint of automotive steering system (조향장치용 볼 조인트 더스트 커버의 형상최적설계)

  • Lee, Boo-Youn;Kim, Ji-Ho
    • Journal of the Korean Society of Marine Engineering
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    • v.37 no.6
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    • pp.603-610
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    • 2013
  • Finite element analysis is performed to evaluate stress and deformation of a wrinkle-type dust cover for the ball joints of tie rods of automotive steering system. Results of the analysis for assembly and operation condition show that sealing capability is good and the maximum stress on the body is smaller than the tensile strength. An optimal shape of the dust cover is obtained using the Taguchi method to reduce the maximum stress. The maximum stress of the optimal design under the operation condition is reduced by 22 per cent of that of the initial design. Results of the research show that performance evaluation and design of the dust covers can be effectively done using the proposed method.

Shape Design Optimization of Electrode for Maximal Dielectrophoresis Forces (최대 유전영동력을 위한 전극의 형상 최적설계)

  • Jeong, Hong-Yeon;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.4
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    • pp.223-231
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    • 2019
  • A continuum-based design sensitivity analysis(DSA) method is developed for electrostatic problems. To consider high order objective functions, we use 9-node finite element basis functions for analysis and DSA methods. As the design variables are parameterized with B-spline functions, smooth boundary variations are naturally obtained. To solve mesh entanglement problems during the optimization process, a mesh regularization scheme is employed. By minimizing the Dirichlet energy functional, mesh uniformity can be automatically achieved. In numerical examples for maximizing dielectrophoresis forces, the numerical results are compared with well-known electrode geometries and the obtained characteristics are discussed.

Shape Scheme and Size Discrete Optimum Design of Plane Steel Trusses Using Improved Genetic Algorithm (개선된 유전자 알고리즘을 이용한 평면 철골트러스의 형상계획 및 단면 이산화 최적설계)

  • Kim, Soo-Won;Yuh, Baeg-Youh;Park, Choon-Wok;Kang, Moon-Myung
    • Journal of the Korean Association for Spatial Structures
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    • v.4 no.2
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    • pp.89-97
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    • 2004
  • The objective of this study is the development of a scheme and discrete optimum design algorithm, which is based on the genetic algorithm. The algorithm can perform both scheme and size optimum designs of plane trusses. The developed Scheme genetic algorithm was implemented in a computer program. For the optimum design, the objective function is the weight of structures and the constraints are limits on loads and serviceability. The basic search method for the optimum design is the genetic algorithm. The algorithm is known to be very efficient for the discrete optimization. However, its application to the complicated structures has been limited because of the extreme time need for a number of structural analyses. This study solves the problem by introducing the size & scheme genetic algorithm operators into the genetic algorithm. The genetic process virtually takes no time. However, the evolutionary process requires a tremendous amount of time for a number of structural analyses. Therefore, the application of the genetic algorithm to the complicated structures is extremely difficult, if not impossible. The scheme genetic algorithm operators was introduced to overcome the problem and to complement the evolutionary process. It is very efficient in the approximate analyses and scheme and size optimization of plane trusses structures and considerably reduces structural analysis time. Scheme and size discrete optimum combined into the genetic algorithm is what makes the practical discrete optimum design of plane fusses structures possible. The efficiency and validity of the developed discrete optimum design algorithm was verified by applying the algorithm to various optimum design examples: plane pratt, howe and warren truss.

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Study of Efficient Aerodynamic Shape Design Optimization with Uncertainties (신뢰성을 고려한 효율적인 공력 형상 최적 설계에 대한 연구)

  • 김수환;권장혁
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.7
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    • pp.18-27
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    • 2006
  • The conventional reliability based design optimization(RBDO) methods require high computational cost compared with the deterministic design optimization(DO) methods, therefore it is hard to apply directly to large-scaled problems such as an aerodynamic shape design optimization. In this study, to overcome this computational limitation the efficient RBDO procedure with the two-point approximation(TPA) and adjoint sensitivity analysis is proposed, that the computational requirement is nearly the same as DO and the reliability accuracy is good compared with that of RBDO. Using this, the 3-D aerodynamic shape design optimization is performed very efficiently.