• Title, Summary, Keyword: Shape design sensitivity

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OPTIMAL SHAPE DESIGN OF ELECTROSTATIC DEVICES USING DESIGN SENSITIVITY ANALYSIS (설계민감도 해석을 이용한 정전소자의 형상최적화)

  • Koh, Chang-Seop;Jung, Hyun-Kyo;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
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    • pp.93-96
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    • 1991
  • This paper describes a new algorithm based on design sensitivity analysis for optimal shape design of electrostatic devices. The design sensitivity, the variation of the object function with respect to the design variables, is derived by using implicit differentiation and direct boundary element methods. The proposed algorithm is applied to the optimal shape design of a concentric cable and the rod electrode enclosed by earthed case, It is shown, from the numerical results, that the algorithm is very usefull for the optimal shape design of the electrostatic devices.

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Isogeometric Shape Design Sensitivity Analysis of Mindlin Plates (민들린 평판의 아이소-지오메트릭 형상 설계민감도 해석)

  • Lee, Seung-Wook;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.4
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    • pp.255-262
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    • 2013
  • In this paper, a shape design sensitivity analysis(DSA) method is presented for Mindlin plates using an isogeometric approach. The isogeometric method possesses desirable advantages; the representation of exact geometry and the higher order inter-element continuity, which lead to the fast convergence of solution as well as accurate sensitivity results. Unlike the finite element methods using linear shape functions, the isogeometric method considers the exact normal vector and curvature of the CAD geometry, taking advantages of higher order NURBS basis functions. A selective reduced integration(SRI) technique is incorporated to overcome the difficulty of 'shear locking' phenomenon. This simple technique is surprisingly helpful for the accuracy of the isogeometric shape sensitivity without complicated formulation. Through the numerical examples of plate bending problems, the accuracy of the proposed isogeometric analysis method is compared with that of finite element one. Also, the isogeometric shape sensitivity turns out to be very accurate when compared with finite difference sensitivity.

Shape Design Optimization Using Isogeometric Analysis (등기하 해석법을 이용한 형상 최적설계)

  • Ha, Seung-Hyun;Cho, Seon-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.21 no.3
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    • pp.233-238
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    • 2008
  • In this paper, a shape design optimization method for linearly elastic problems is developed using isogeometric approach. In many design optimization problems for practical engineering models, initial raw data usually come from a CAD modeler. Then, designers should convert the CAD data into finite element mesh data since most of conventional design optimization tools are based on finite element analysis. During this conversion, there are some numerical errors due to geometric approximation, which causes accuracy problems in response as well as design sensitivity analyses. As a remedy for this phenomenon, the isogeometric analysis method can be one of the promising approaches for the shape design optimization. The main idea of isogeometric approach is that the basis functions used in analysis is exactly the same as the ones representing the geometry. This geometrically exact model can be used in the shape sensitivity analysis and design optimization as well. Therefore the shape design sensitivity with high accuracy can be obtained, which is very essential for a gradient-based optimization. Through numerical examples, it is verified that the shape design optimization based on an isogeometic approach works well.

Study on Configuration Design Sensitivity of Noise & Vibration (소음/진동의 컨피규레이션 설계 민감도 연구)

  • 왕세명;기성현
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.192-198
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    • 1997
  • In the concurrent engineering, the CAD-based design model is necessary for multidisciplinary analysis and for computer-aided manufacturing (CAM). A shape and configuration design velocity field computation of structure has been developed using a computer-aided design (CAD) tool, Pro/ENGINEER. The design Parameterization with CAD tool is to characterize the change in dimensions and movements of geometric control points that govern the shape/orientation of the structural boundary. The boundary velocity is obtained by using a CAD-based finite difference method and the domain velocity field is obtained from finite element analysis (FEA) using the boundary displacement method. In this paper, the continuum configuration DSA for NVH problem, which requires the shape velocity field and the orientation velocity field at the same time, is developed using linear shape functions. For validation of continuum design sensitivity coefficients, design sensitivity coefficients are compared with the coefficients computed using by the finite difference method.

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Shape Design Sensitivity Analysis of Thermal Conduction Problems using Commercial Software ANSYS (상용 소프트웨어 ANSYS를 이용한 열전도문제의 형상설계 민감도 해석)

  • Choe, Ju-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.3
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    • pp.645-652
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    • 2000
  • A method for shape design sensitivity analysis is proposed utilizing commercial software ANSYS for thermal conduction problems. While the sensitivity formula is derived analytically by introduing adjoint variable concept, sensitivity calculation in practice as well as the primal and adjoint solution of thermal conduction is performed using the ANSYS very easily. Since the formula always takes boundary integral form, sensitivity evaluation in ANSYS requires a little more addition of post-processing routine which involves evaluation of boundary variable from the obtained solution. Though the BEM has been used as a better tool for this purpose, the present study shows it can also be calculated using any kind of analysis code such as ANSYS since the formula is based on analytic nature. Therefore the present study provides a new and efficient way of optimization which was not possible before using commercial software. The usefulness of the method is illustrated via a weight minimization problem of thermal diffuser.

3D Shape Optimization of Nonlinear Electromagnetic Device Using Parameterized Sensitivity Analysis (매개화된 민감도 해석에 의한 3차원 비선형 모델의 형상 최적화)

  • Ryu, Jae-Seop;Koh, Chang-Seop;Yun, So-Nam
    • Proceedings of the KIEE Conference
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    • pp.915-917
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    • 2003
  • In this paper, a 3D shape optimization algorithm which guarantees a smooth optimal shape is presented using parameterized sensitivity analysis. The design surface is parameterized using Bezier spline and the control points of the spline are taken as the design variables. The parameterized sensitivity for the control points are found from that for nodal Points. The design sensitivity and adjoint variable formulae are also derived for the 3D non-linear problems. Through an application to the shape optimization of 3D electromagnet to get a uniform magnetic field, the effectiveness of the proposed algorithm is shown.

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A Magnet Pole Shape Optimization of a Large Scale BLDC Motor Using a RSM With Design Sensitivity Analysis (민감도기법과 RSM을 이용한 대용량 BLDC 전동기 영구자석의 형상 최적화)

  • Shin, Pan-Seok;Chung, Hyun-Koo;Woo, Sung-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.4
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    • pp.735-741
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    • 2009
  • This paper presents an algorithm for the permanent magnet shape optimization of a large scale BLDC(Brushless DC) motor to minimize the cogging torque. A response surface method (RSM) using multiquadric radial basis function is employed to interpolate the objective function in design parameter space. In order to get a reasonable response surface with relatively small number of sampling data points, additional sampling points are added on the basis of design sensitivity analysis computed by using FEM. The algorithm has 2 stages: the first stage is to determine the PM arc angle, and the 2nd stage is to optimize the magnet pole shape. The developed algorithm is applied to a 5MW BLDC motor to get a minimum cogging torque. After 3 iterations with 4 design parameters, the cogging torque is reduced to 13.2% of the initial one.

Boundary Method for Shape Design Sensitivity Analysis in Solving Free-Surface Flow Problems

  • Choi Joo Ho;Kwak H. G.;Grandhi R. V.
    • Journal of Mechanical Science and Technology
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    • v.19 no.12
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    • pp.2231-2244
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    • 2005
  • An efficient boundary-based optimization technique is applied in the numerical computation of free surface flow problems, by reformulating them into the equivalent optimal shape design problems. While the sensitivity in the boundary method has mainly been calculated using the boundary element method (BEM) as an analysis means, the finite element method (FEM) is used in this study because of its popularity and easy-to-use features. The advantage of boundary method is that the design velocity vectors are needed only on the boundary, not over the whole domain. As such, a determination of the complicated domain design velocity field, which is necessary in the domain method, is eliminated, thereby making the process easy to implement and efficient. Seepage and supercavitating flow problem are chosen to illustrate the accuracy and effectiveness of the proposed method.

Shape Design Sensitivity Analysis of Dynamic Crack Propagation Problems using Peridynamics and Parallel Computation (페리다이나믹스 이론과 병렬연산을 이용한 균열진전 문제의 형상 설계민감도 해석)

  • Kim, Jae-Hyun;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.4
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    • pp.297-303
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    • 2014
  • Using the bond-based peridynamics and the parallel computation with binary decomposition, an adjoint shape design sensitivity analysis(DSA) method is developed for the dynamic crack propagation problems. The peridynamics includes the successive branching of cracks and employs the explicit scheme of time integration. The adjoint variable method is generally not suitable for path-dependent problems but employed since the path of response analysis is readily available. The accuracy of analytical design sensitivity is verified by comparing it with the finite difference one. The finite difference method is susceptible to the amount of design perturbations and could result in inaccurate design sensitivity for highly nonlinear peridynamics problems with respect to the design. It turns out that $C^1$-continuous volume fraction is necessary for the accurate evaluation of shape design sensitivity in peridynamic discretization.

A Study on The Optimization of Three-Dimensional Forging Processes Using The Sensitivity Method (민감도 해석을 이용한 3차원 단조공정의 최적설계에 대한 연구)

  • Lee S. R.;Yang D. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.277-280
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    • 2005
  • A shape optimization is applied to achieve a design objective in three-dimensional forging processes. In multi-stage forging processes, among the important design aspects, the die shape fur preforming is regarded as the design variable since it influences the forged part relatively higher than the others. The rigid-plastic finite element method and the sensitivity method are employed and formulated to solve a formulated optimization problem. An approximation scheme is also used for the direction search during the optimization. The upset forging of a square box is selected as a test example in order to demonstrate and verify the optimization process of this study. After the optimization, the optimized shape of the die yields a finial product of desire shape.

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