• Title, Summary, Keyword: Shape design sensitivity

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Sensitivity and optimisation procedures for truss structures under large displacement

  • Bothma, A.S.;Ronda, J.;Kleiber, M.
    • Structural Engineering and Mechanics
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    • v.7 no.1
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    • pp.111-126
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    • 1999
  • The work presented here focuses on the development of suitable discretised formulations, for large-displacement shape and non-shape design sensitivity analysis (DSA), which enable the straightforward incorporation of structural optimisation into established finite element analysis (FEA) codes. For the generalised displacement-based functional the design sensitivity vector has been expressed in terms of displacement sensitivity. The Total Lagrangian formulation is utilised for modelling of large deformation of truss structures. The variational formulation of the sensitivity analysis procedure is discretised by using "pseudo" - finite elements, Results are presented for the sensitivity analysis and optimisation of standard truss structures. For the purposes of this work, the analysis and optimisation procedures outlined below are incorporated into the FEA code ABAQUS.

Eigenvalue Design Sensitivity Analysis To Redesign Spacer Grid Location In Nuclear Fuel Assembly (핵연료집합체 지지격자 위치결정을 위한 고유치 민감도해석)

  • 박남규;이성기;김형구;최기성;이준노;김재원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.705-709
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    • 2002
  • The spacer grids in nuclear fuel assembly locate and align the fuel rods with respect to each other. They provide axial and lateral restraint against an excessive rod motion mainly caused by coolant flow. It is understood that each rod Is supported by multiple spacer grid. In such a case, it is important to determine spacer grid span so as to avoid resonance between the natural frequency of the fuel rods and excitation frequency. Actually dynamic characteristics of the fuel rods can be improved by assigning adequate spacer grid locations. When a dynamic performance of the structure is to be improved, design sensitivity analysis plays an important role as like many structural redesign problems. In this work, a shape design concept, different from conventional design, was applied to the problem. According to the theory shape can be a design parameter and optimal shape design can be found. This study concentrates on eigenvalue design sensitivity of the fuel rod supported by multiple spacer grids to determine optimal spacer grids positions.

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Design Sensitivity Analysis for the Optimal Shape Design of Magnetostatic Problems (정자계 문제의 형상 최적 설계를 위한 설계 민감도 해석)

  • Koh, Chang-Seop;Hahn, Song-Yop;Jung, Hyun-Kyo
    • Proceedings of the KIEE Conference
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    • pp.567-569
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    • 1992
  • Design sensitivity analysis is proposed for the optimal shape design of three dimensional magnetostatic problems. The direct differentiation method is introduced for design sensitivity analysis and the boundary element method with reduced magnetic scalar potential as the state variable is used to analyze the magnetic characteristics. In the direct differentiation method, the design sensitivity, defined as the total derivative of the objective function with respect to the design variables, is calculated based on the variation of the state variable with respect to the design variable. And the variation of He state variable is calculated by differentiating the both sides of the system matrix equation obtained by applying boundary element method. Through the numerical example with simple electromagnet, the usefullness is proved.

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Shape Optimization for Reduction of Cogging Torque in Permanent Magnet Motor by Sensitivity Analysis (영구자석전동기의 코깅토오크저감을 위한 민감도에 의한 형상최적화)

  • Park, Il-Han;Lee, Beom-Taek;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
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    • pp.19-22
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    • 1990
  • In this paper, in order to reduce the cogging torque in a permanent motor, a method to optimize the shape of permanent magnet and iron pole is presented. Because the cogging torque comes from the irregular system energy variation according to the rotor position, system energy variation is taken as object function and the object function is minimized to optimize the shape. The positions of permanent magnet surface and iron pole surface are chosen as design parameters and sensitivity of object function with respect to design parameter is calculated. The shape is changed according to sensitivity. Sensitivity can be generated by methods that exploit the FEM formulation. A numerical example shows that about 90% of the original cogging torque is reduced.

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Shape Design Optimization of Fluid-Structure Interaction Problems (유체-구조 연성 문제의 형상 최적설계)

  • Ha, Yoon-Do;Kim, Min-Geun;Cho, Hyun-Gyu;Cho, Seon-Ho
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.2
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    • pp.130-138
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    • 2007
  • A coupled variational equation for fluid-structure interaction (FSI) problems is derived from a steady state Navier-Stokes equation for incompressible Newtonian fluid and an equilibrium equation for geometrically nonlinear structures. For a fully coupled FSI formulation, between fluid and structures, a traction continuity condition is considered at interfaces where a no-slip condition is imposed. Under total Lagrange formulation in the structural domain, finite rotations are well described by using the second Piola-Kirchhoff stress and Green-Lagrange strain tensors. An adjoint shape design sensitivity analysis (DSA) method based on material derivative approach is applied to the FSI problem to develop a shape design optimization method. Demonstrating some numerical examples, the accuracy and efficiency of the developed DSA method is verified in comparison with finite difference sensitivity. Also, for the FSI problems, a shape design optimization is performed to obtain a maximal stiffness structure satisfying an allowable volume constraint.

Optimal Design of Dielectric shape and Topology using Smooth Boundary Topology Optimization Method (부드러운 경계 위상 최적설계기법을 이용한 유전체 형상 및 위상 최적설계)

  • Jeung, Gi-Woo;Choi, Nak-Sun;Kim, Nam-Kyung;Kim, Dong-Hun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.1936-1941
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    • 2009
  • This paper deals with a new methodology for topology optimization in which the topology of the design domain may change during the shape optimization process. To achieve this, the concept of the topological gradient is introduced to compute the sensitivity of an objective function when a small hole is drilled in the domain. Based on shape and topological sensitivity values, the shape and topology of the design domain may be simultaneously changed during design iterations if necessary. To verify the advantages and also to facilitate understanding of the method itself, two electrostatic design problems have been tested by using 2D finite element analysis: the first is the inverse problem of a simple dielectric model and the second is the rotor design of a MEMS actuator.

Shape Design Sensitivity Analysis of Axisymmetric Thermal Conducting Solids Using Boundary Integral Equations (경계적분방정식을 이용한 축대칭 열전도 고체의 형상설계민감도 해석)

  • 이부윤
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.1
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    • pp.141-152
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    • 1993
  • A generalized method is presented for shape design sensitivity analysis of axisymmetric thermal conducting solids. The shape sensitivity formula of a general performance functional arising in shape optimal design problem is derived using the material derivative concept and the adjoint variable method. The method for deriving the formula is based on standard axisymmetric boundary integral equation formulation. It is then applied to obtain the sensitivity formulas for temperature and heat flux constraints imposed over a small segment of the boundary. To show the accuracy of the sensitivity analysis, numerical implementations are done for three examples. Sensitivities calculated by the presented method are compared with analytic sensitivities for two examples with analytic solutions, and compared with sensitivies by finite difference for a cooling fin example.

Shape Design Optimization of Ship Structures Considering Thermal Deformation and Target Shape (열 변형과 목적형상을 고려한 선체구조의 형상 최적설계)

  • Park, Sung-Ho;Choi, Jae-Yeon;Kim, Min-Geun;Cho, Seon-Ho
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.3
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    • pp.430-437
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    • 2010
  • In this paper, we develop a shape design optimization method for thermo-elastoplasticity problems that is applicable to the welding or thermal deformation problems of ship structures. Shell elements and a programming language APDL in a commercial finite element analysis code, ANSYS, are employed in the shape optimization. The point of developed method is to determine the design parameters such that the deformed shape after welding fits very well to a desired design. The geometric parameters of surfaces are selected as the design parameters. The modified method of feasible direction (MMFD) and finite difference sensitivity are used for the optimization algorithm. Two numerical examples demonstrate that the developed shape design method is applicable to existing hull structures and effective for the structural design of ships.

Shape Design Sensitivity Analysis Case of the Valves installed in the Hydraulic Driving Motor (사판식 구동모터에 장착된 밸브의 설계변수 민감도 해석 사례)

  • Noh, Dae-Kyung;Jang, Joo-Sup
    • Journal of the Korea Society for Simulation
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    • v.22 no.3
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    • pp.81-87
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    • 2013
  • This paper is about study how to decrese surge pressure that is occurred in excavator driving motor. We used computer simulation program SimulationX. It is also about the way finding design problem and approaching a solution through interpreting shape design sensitivity analysis. Programmes are below. First of all, finding shape fault by analyzing dynamic behavior of valves installed in hydraulic driving motor which is designed now. And drawing variable which is considered sensitive to improve dynamic efficiency among a lot of shape variables. Then, targeting that variable and examining dynamic efficiency stabilization tendency with controlling it. Finally, suggesting the most effective tuning method through variable combination as there are a lot of sensitive variables.

OPTIMAL SHAPE DESIGN OF A S-SHAPED SUBSONIC INTAKE USING NURBS (NURBS를 이용한 S형 천음속 흡입관 최적 설계)

  • Lee B.J.;Kim C.
    • Journal of computational fluids engineering
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    • v.11 no.1
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    • pp.57-66
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    • 2006
  • An optimal shape design approach is presented for a subsonic S-shaped intake using aerodynamic sensitivity analysis. Two-equation turbulence model is employed to capture strong counter vortices in the S-shaped duct more precisely. Sensitivity analysis is performed for the three-dimensional Navier-Stokes equations coupled with two-equation turbulence models using a discrete adjoint method For code validation, the result of the flow solver is compared with experiment data and other computational results of bench marking test. To study the influence oj turbulence models and grid refinement on the duct flow analysis, the results from several turbulence models are compared with one another and the minimum number of grid points, which can yield an accurate solution is investigated The adjoint variable code is validated by comparing the complex step derivative results. To realize a sufficient and flexible design space, NURBS equations are introduced as a geometric representation and a new grid modification technique, Least Square NURBS Grid Approximation is applied With the verified flow solver, the sensitivity analysis code and the geometric modification technique, the optimization of S-shaped intake is carried out and the enhancement of overall intake performance is achieved The designed S-shaped duct is tested in several off-design conditions to confirm the robustness of the current design approach. As a result, the capability and the efficiency of the present design tools are successfully demonstrated in three-dimensional highly turbulent internal flow design and off-design conditions.