• Title, Summary, Keyword: Shape design sensitivity

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Shape Design of Induction Motors for Efficiency Improvement (유도기 효율향상을 위한 회전자슬롯 형상최적화)

  • Kwak, In-Gu;Lee, Hyang-Beom;Park, Il-Han;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
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    • pp.929-931
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    • 1993
  • The design sensitivity analysis based on the finite element method is presented for the eddy current problem with a voltage source. Since, in this problem, the complex variable is used as the state variable, new approach to the sensitivity calculation for the complex variable system is required. Its result is applied to the design of the rotor slot shape of squirrel cage induction motor. As a analysis model, only one slot pitch of rotor is analyzed by using a Periodic boundary condition. The use of this minimal modelling method leads to much saving of calculation time. The design objective is to obtain the desired slip-torque characteristic. Because the shape of rotor slot has much influence on the slip torque characteristic, the design variables are taken on the interface shape between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal type with rounding corners. The obtained final shape is quite similar to the double squirrel cage type.

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Shape Optimum Design of Cantilever with Weight and Journal Bearing Cap (자중을 고려한 외팔보와 저널 베어링 덮개의 형상 최적설계)

  • Lim, O-Kang;Lee, Jin-Suk;Cho, Heon;Lee, Byung-Woo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.3
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    • pp.427-435
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    • 1999
  • In the field of shape optimum design, much efforts are needed in regridding method and shape design sensitivity analysis. In this paper, Bezier curve is used to make the boundary of a structure and the improved direct differentiation method is used to calculate the shape design sensitivity. To regrid the finite element model, modified displacement field is presented in this paper. The modified displacement field makes more fine grid at large curvature. The purpose of this paper is to obtain the optimum shape of a cantilever with weight and a 3-dimensional journal bearing cap.

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Topological Design Sensitivity on the Air Bearing Surface of Head Slider

  • Yoon, Sang-Joon;Kim, Min-Soo;Park, Dong-Hoon
    • Journal of Mechanical Science and Technology
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    • v.16 no.8
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    • pp.1102-1108
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    • 2002
  • In this study, a topological design sensitivity of the ai. bearing surface (ABS) is suggested by using an adjoint variable method. The discrete form of the generalized lubrication equation based on a control volume formulation is used as a compatible condition. A residual function of the slider is considered as an equality constraint function, which represents the slider in equilibrium. The slider thickness parameters at all grid cells are chosen as design variables since they are the topological parameters determining the ABS shape. Then, a complicated adjoint variable equation is formulated to directly handle the highly nonlinear and asymmetric coefficient matrix and vector in the discrete system equation of air-lubricated slider bearings. An alternating direction implicit (ADI) scheme is utilized for the numerical calculation. This is an efficient iterative solver to solve large-scale problem in special band storage. Then, a computer program is developed and applied to a slider model of a sophisticated shape. The simulation results of design sensitivity analysis (DSA) are directly compared with those of FDM at the randomly selected grid cells to show the effectiveness of the proposed approach. The overall distribution of DSA results are reported, clearly showing the region on the ABS where special attention should be given during the manufacturing process.

Shape Optimization of Piezoelectric Materials for Piezoelectric-Structure-Acoustic System (압전-구조-음향 연성계의 압전 액츄에이터 최적설계)

  • Wang, Se-Myung;Lee, Kang-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1627-1632
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    • 2000
  • Recently, piezoelectric materials have attracted considerable attention because of its self-sensing and actuating properties. To model smart structures, numerical modeling of structures with piezoelectric devices is essential. As many factors affect the performance of smart structures, optimization of these parameters is necessary. In this paper, the shape design sensitivity analysis of the 3D piezoelectric and structural elements is developed and shape optimization is performed. For the evaluation of the sensitivity, the finite element method is used. For the shape sensitivity, the domain velocity field is calculated. An acoustic cavity model is presented as a numerical example to study the feasibility of the formulation. The continuum sensitivity is compared with the results of the finite difference method by ANSYS. And the sequential linear programming (SLP) algorithm is used as the optimization algorithm.

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Optimal Shape Design of a Container Under Hot Isostatic Pressing by a Finite Element Method (열간등가압소결 공정에서 유한요소법을 이용한 컨테이너 형상의 최적설계)

  • Jeong, Seok-Hwan;Park, Hwan;Jeon, Gyeong-Dal;Kim, Gi-Tae;Hwang, Sang-Mu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9
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    • pp.2211-2219
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    • 2000
  • Near net shape forming of 316L stainless steel powder was investigated under hot isostatic pressing. To simulate densification and deformation of a powder compact in a container during hot isostatic pressing, the constitutive model of Abouaf and co-workers was implemented into a finite element analysis. An optimal design technique based on the design sensitivity was applied to the container design during hot isostatic pressing. The optimal shape of the container was predicted from the desired final shape of a powder compact by iterative calculations. Experimental data of 316L stainless steel powder showed that the optimally designed container allowed precise forming of the desired powder compact during hot isostatic pressing.

Shape Design of Electrode by Sensitivity Analysis (민감도 해석에 의한 전극의 형상설계)

  • Lee, Beom-Taek;Park, Il-Han;Hahn, Song-Yop
    • Proceedings of the KIEE Conference
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    • pp.15-18
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    • 1990
  • In this paper, in order to optimize the shape of electrode to achieve prescribed electric field intensity distribution along the surface of electrode, sensitivity analysis based on finite element method is proposed. The objective function of this problem is the difference of calculated electric field intensity at given design and prescribed electric field intensity. So, the problem is to find the shape of electrode to minimize the objective function defined above. The result of numerical example shows that maximum electric field error is about 0.1% and the usefulness of this shape optimal design procedure.

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Kinematic Design Sensitivity Analysis of Suspension systems Using Direct differentiation (직접미분법을 이용한 현가장치의 기구학적 민감도해석)

  • 민현기;탁태오;이장무
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.1
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    • pp.38-48
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    • 1997
  • A method for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. For modeling of vehicle suspensions, the multibody dynamic formulation is adopted, where suspensions are assumed as combination of rigid bodies and ideal frictionless joints. In a relative joint coordinate setting, kinematic constraint equations are obtained by imposing cut-joints that transform closed-loop shape suspension systems into open-loop systems. By directly differentiating the constraint equations with respect to kinematic design variables, such as length of bodies, notion axis, etc., sensitivity equations are derived. By solving the sensitivity equations, sensitivity of static design factors that can be used for design improvement, can be obtained. The validity and usefulness of the method are demonstrated through an example where kinematic sensitivity analysis of a MacPherson strut suspension of performed.

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Sensitivity Control and Design of the Silicone Foot Sensor Using FEM (유한요소 해석을 통한 실리콘 족적 센서의 감도 조절 및 설계)

  • Seong, Byuck Kyung;Seo, Hyung Kyu;Lee, Jin Wook;Kwon, Ae-Ran;Kim, Dong Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.11
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    • pp.1041-1050
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    • 2014
  • A design and analysis for new foot sensor that measures pressure distribution while walking or running in daily life is introduced. In the process of the sensor design, the shape, mechanism composing of the sensor, and variables that dominate sensor's sensitivity are investigated. Through these variables analysis, an optimal shape and dimension were determined. The effects of variables on sensor's sensitivity and the relationship between each variable are proved by analyses and experiments.

Multi-Point Aerodynamic Shape Optimization of Rotor Blades Using Unstructured Meshes

  • Lee, Sang-Wook;Kwon, Oh-Joon
    • International Journal of Aeronautical and Space Sciences
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    • v.8 no.1
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    • pp.66-78
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    • 2007
  • A multi-point aerodynamic shape optimization technique has been developed for helicopter rotor blades in hover based on a continuous adjoint method on unstructured meshes. The Euler flow solver and the continuous adjoint sensitivity analysis were formulated on the rotating frame of reference. The 'objective function and the sensitivity were obtained as a weighted sum of the values at each design point. The blade section contour was modified by using the Hicks-Henne shape functions. The mesh movement due to the blade geometry change was achieved by using a spring analogy. In order to handle the repeated evaluation of the design cycle efficiently, the flow and adjoint solvers were parallelized based on a domain decomposition strategy. A solution-adaptive mesh refinement technique was adopted for the accurate capturing of the wake. Applications were made to the aerodynamic shape optimization of the Caradonna-Tung rotor blades and the UH-60 rotor blades in hover.

Shape Design Sensitivity Analysis and Optimization of Axisymmetric Shell Structures (축대칭 쉘구조물의 형상 설계민감도 해석 및 최적설계)

  • 김인용;곽병만
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.98-105
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    • 1993
  • A method for shape design sensitivity analysis for axisymmetric shells of general shapes is developed. The basic approach is to divide the structures into many segments. For each of the segments, the formula for a shallow arch or shell can be applied and the results assembled. To interconnect those segments, the existing sensitivity formula, obtained for a variation only in the direction perpendicular to the plane on which the structure is mapped, has been extended to include a variation normal to the middle surface. The method follows the adjoint variable approach based on the material derivative concept as established in the literature. Numerical examples are taken to illustrate the method and the applicability to practical design problems.

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