• Title, Summary, Keyword: Shape design sensitivity

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X-FEM Based Shape Design Sensitivity Analysis of Crack Propagation Problems (균열진전 문제의 X-FEM 기반 형상 설계민감도 해석)

  • Moon, Min-Yeong;Ahn, Seung-Ho;Cho, Seon-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.697-700
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    • 2011
  • 본 논문에서는 X-FEM을 사용하여 혼합모드 하중 상태에서의 이차원 선형탄성체의 균열문제에 대한 형상 설계민감도 해석을 수행하였다. X-FEM이란 균열과 같은 특수한 해를 근사하는 방법으로써, 확장함수를 도입하여 FEM의 한계를 극복하는 방법론이다. X-FEM 하에서 해를 근사하는 데 쓰이는 확장함수들은 불연속성과 특이성을 포함하고 있어 물리적 영역에 의존한다. 이는 설계민감도 해석을 수행하는 과정에서 그러한 의존성을 고려해주는 것이 필요하다. 따라서 본 논문에서는 X-FEM 기반의 형상 설계민감도 해석해를 제안하고자 한다. 식의 유도는 전 미분 공식에 기초하고 있으며, 형상함수의 설계변분에 대한 의존성에 관한 항을 추가시켰다. 또한, 균열 주위의 국부적인 공간에서의 확장된 자유도에 설계속도를 가한다. 이에 대한 몇 가지 수치 예제를 통하여 개발된 방법론의 타당성을 확인하였다.

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Design Optimization for vehicle Pillar Section Shape Using Simple Finite Element Model (단순유한요소모델을 이용한 차체필라 형상최적설계)

  • 이상범
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.133-139
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    • 2000
  • Vibrational characteristics of the vehicle structure are mainly influenced by the shape of the pillar cross section. In this paper a vehicle structural optimization technique has been developed to investigate a lightweight vehicle structure subject to constraints on natural frequencies in a simple beam-and-shell model. In this technique, the optimization procedures involve two stages. In the first stage, the section procedures involve tow stages. In the first stage, the section properties of beam elements of the vehicle structure has been optimized to have minimum weight while satisfying the constraints of natural frequencies. And, in the second stage, the shape of the cross section of the elements of the structure has been determined.

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Shape Optimization of Shell Surfaces Based on Linkage Framework between B-spline Modeling and Finite Element Analysis (유한요소해석과 B-스플라인 모델링의 연동에 기초한 쉘 곡면의 형상 최적 설계)

  • 김현철;노희열;조맹효
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.169-176
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    • 2003
  • In the present study, a shape design optimization scheme in shell structures is implemented based on the integrated framework of geometric modeling and analysis. The common representation of B-spline surface patch is used for geometric modeling. A geometrically-exact shell finite element is implemented. Control points or the surface are employed as design variables. In the computation of shape sensitivity, semi-analytical method is employed. Sequential linear programming is applied to the shape optimization of surfaces. The developed integrated framework should serve as a powerful tool to design and analysis of surfaces.

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A two-step method for the optimum design of trusses with commercially available sections

  • Oral, Suha;Uz, Atilla
    • Structural Engineering and Mechanics
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    • v.5 no.1
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    • pp.59-68
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    • 1997
  • A two-step method is presented for the optimum design of trusses with available sections under stress and Euler buckling constraints. The shape design of the truss is used as a means to convert the discrete solution into a continuous one. In the first step of the method, a continuous solution is obtained by sizing and shape design using an approximate polynomial expression for the buckling coefficients. In the second step, the member sizes obtained are changed to the nearest available sections and the truss is reconfigured by using the exact values for the buckling coefficients. The optimizer used is based on the sequential quadratic programming and the gradients are evaluated in closed form. The method is illustrated by two numerical examples.

H-refined Shape Design Sensitivity Analysis of Elastic Structures using Multi-Resolution Approach (다중 조밀도를 이용한 탄성 구조의 h-세분화 아이소-지오메트릭 설계민감도 해석)

  • Lee, Taeho;Yoon, Minho;Cho, Seonho;Koo, Bonyong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.31 no.3
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    • pp.155-163
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    • 2018
  • One of the major disadvantages of isogeometric analysis(IGA) is that local refinement is nearly impossible in a conventional manner because of the tensor product nature in NURBS. In this research, we investigate a local refinement scheme for isogeometric analysis, named multi-resolution approach where different resolutions are employed at each subdomain, using h-refinement relation to endow displacement compatibility on an interface of subdomains. Then, we develop shape sensitivity analysis possessing same compatibility condition as in the analysis. Numerical examples are shown to demonstrate the computational efficiency of the method in analysis especially stress concentration problem and accurate sensitivity results which is also compatible on the interface.

A Refined Semi-Analytic Sensitivity Study Based on the Mode Decomposition and Neumann Series Expansion in Eigenvalue Problem(II) - Eigenvalue Problem - (강체모드분리와 급수전개를 통한 고유치 문제에서의 준해석적 설계 민감도 개선에 관한 연구(II) -동적 문제 -)

  • Kim, Hyun-Gi;Cho, Maeng-Hyo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.4
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    • pp.593-600
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    • 2003
  • Structural optimization often requires the evaluation of design sensitivities. The Semi Analytic Method(SAM) fur computing sensitivity is popular in shape optimization because this method has several advantages. But when relatively large rigid body motions are identified for individual elements. the SAM shows severe inaccuracy. In this study, the improvement of design sensitivities corresponding to the rigid body mode is evaluated by exact differentiation of the rigid body modes. Moreover. the error of the SAM caused by numerical difference scheme is alleviated by using a series approximation for the sensitivity derivatives and considering the higher order terms. Finally the present study shows that the refined SAM including the iterative method improves the results of sensitivity analysis in dynamic problems.

A Study on Reducing Rolling Mode Effect in High-Sensitivity Optical Pickup 3-axis Actuator (고감도 3축구동 액츄에이터를 위한 Rolling Mode 저감 연구)

  • 김영중;홍삼열;김진아;최인호
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.775-779
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    • 2003
  • Recently, a new type actuator using multi-pole magnet has been developed for high-density and high-speed disk drive, which can be achieved higher sensitivity than a conventional actuator for applying one-pole magnet. However, it is very difficult for the actuator of multi-pole magnet to meet simultaneously the optimal design condition for reducing rolling mode effect and improving driving sensitivity because the force center is different from the mass center In this paper, First We propose the new shape coil for tracking which can reverse moment additionally in tracking motion, Next we achieve the optimal design to reduce phase disturbance and peak gain at the rolling mode frequency. Finally, the validity of the proposed methods is proved from experimental results.

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Aerodynamic Shape Optimization using Discrete Adjoint Formulation based on Overset Mesh System

  • Lee, Byung-Joon;Yim, Jin-Woo;Yi, Jun-Sok;Kim, Chong-Am
    • International Journal of Aeronautical and Space Sciences
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    • v.8 no.1
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    • pp.95-104
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    • 2007
  • A new design approach of complex geometries such as wing/body configuration is arranged by using overset mesh techniques under large scale computing environment. For an in-depth study of the flow physics and highly accurate design, several special overlapped structured blocks such as collar grid, tip-cap grid, and etc. which are commonly used in refined drag prediction are adopted to consider the applicability of the present design tools to practical problems. Various pre- and post-processing techniques for overset flow analysis and sensitivity analysis are devised or implemented to resolve overset mesh techniques into the design optimization problem based on Gradient Based Optimization Method (GBOM). In the pre-processing, the convergence characteristics of the flow solver and sensitivity analysis are improved by overlap optimization method. Moreover, a new post-processing method, Spline-Boundary Intersecting Grid (S-BIG) scheme, is proposed by considering the ratio of cell area for more refined prediction of aerodynamic coefficients and efficient evaluation of their sensitivities under parallel computing environment. With respect to the sensitivity analysis, discrete adjoint formulations for overset boundary conditions are derived by a full hand-differentiation. A smooth geometric modification on the overlapped surface boundaries and evaluation of grid sensitivities can be performed by mapping from planform coordinate to the surface meshes with Hicks-Henne function. Careful design works for the drag minimization problems of a transonic wing and a wing/body configuration are performed by using the newly-developed and -applied overset mesh techniques. The results from design applications demonstrate the capability of the present design approach successfully.

Design of Drive Line Shape for Reflective Magneto-Optic Spatial Light Modulator with High Switching Sensitivity by Computer Simulation (컴퓨터 시뮬레이션을 통한 고 스위칭 감도를 갖는 반사형 자기 광학 공간 광 변조기의 드라이브 라인 형상 설계)

  • 박재혁;조재경
    • Journal of the Korean Magnetics Society
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    • v.10 no.2
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    • pp.93-98
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    • 2000
  • Drive line shape for reflective magneto-optic spatial light modulator has been designed by computer simulation. A factor of 3 improvement in pixel switching sensitivity and power consumption, compared to the conventional reflective magneto-optic spatial light modulator, has been achieved by the use of wedge-shape drive line and a soft magnetic layer. A factor of 2 higher optical efficiency and a factor of 2 simpler fabrication process have been achieved by the use of drive lines that covers most of the surface of pixel and unpatterned insulator.

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A Study on The Development of The Relationship Model of Building Facades and Exterior Lighting for Streetscape Design (가로경관 조명설계를 위한 건축물 외관유형과 경관조명방식과의 상관관계모델 개발에 관한 연구)

  • 김미연;최진원
    • Korean Institute of Interior Design Journal
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    • no.40
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    • pp.139-148
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    • 2003
  • For lighting design in such diverse structures, we need lots of considerations, such as use and characteristics of the structure, harmony with its surroundings, and the function and type of lighting to be installed. The structural characteristics is determined by its shape and several vertical and horizontal factors based on the shape, which can be focused on at day time by shading, the surface structure, the quality of the surface and the color. On the other hand, they can be at night hidden in the darkness or enforced strongly by the effect of the lighting. In this paper, correlation between the ways of lighting and building facade types according to vocabularies for sensitivity is explored based upon an analysis of building facades for small-scale commerce which plays an important role in cityscape lighting design. It is considered that categorization of types of building facades, presented in this article, and the classification system of exterior lighting methods can be useful in planning lighting. And the process of the study is thought to be able to present a method about the exterior lighting planning. Furthermore, computer simulation on the bases of the correlation model of the lighting methods related to vocabularies for sensitivity about the building facade types is expected to be data and means which can be a great help for designers to predict various results quickly.