• Title/Summary/Keyword: Shape optimization

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Application of the Growth-Strain Method for Shape Optimization (형상 최적화를 위한 성장-변형률법의 적용)

  • 이경래
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.2
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    • pp.27-34
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    • 1999
  • The growth-strain method was used for shape optimization, which carries out the optimization by distributing uniformly the distributed parameter such as von Mises stress and shear strain energy density. Shape optimization is carried out by iteration of stress analysis and growth strain analysis. In this study, the effect of growth ratio in the method was investigated and then the range of the adequate value of the growth ratio was determined. Also the growth-strain method was improved by applying the linear PID control theory in order to control volume required by a designer. Finally, an automatic shape optimization system was built up by the improved growth-strain method with a commercial software using finite element method. The effectiveness and practicability of the developed shape optimization system was verified by some examples.

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Shape Optimization of Three-Dimensional Cutouts in Laminated Composite Plates (삼차원 적층복합재 구멍의 형상 최적화)

  • 한석영;마영준
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.275-280
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    • 2004
  • Shape optimization was performed to obtain the precise shape of cutouts including the internal shape of cutouts in laminated composite plates by three dimensional modeling using solid element. The volume control of the growth-strain method was implemented and the distributed parameter chosen as Tsai-Hill fracture index for shape optimization. The volume control of the growth-strain method makes Tsai-Hill failure index at each element uniform in laminated composites under the initial volume. Then shapes optimized by Tsai-Hill failure index were compared with those of the initial shapes for the various load conditions and cutouts. The following conclusions were obtained in this study. (1) It was found that growth-strain method was applied efficiently to shape optimization of three dimensional cutouts in a laminate composite, (2) The optimal shapes of the various load conditions and cutouts were obtained, (3) The maximum Tsal-Hill failure index was reduced up to 67% when shape optimization was peformed under the initial volume by volume control of growth-strain method.

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Shape Optimization for Multi-Connected Structures (다연결체 구조물에 대한 형상 최적화)

  • 한석영;배현우
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.2
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    • pp.151-158
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    • 2000
  • The growth-strain method was used for shape optimization of multi-connected structures. It was verified that the growth-strain method is very effective for shape optimization of structures with only one free surface to be deformed. But it could not provide reasonable optimized shape for multi-connected structures, when the growth-strain method is applied as it is. The purpose of this study is to improve the growth-strain method for shape optimization of multi-connected two- and three- dimensional structures. In order to improve, the problems that occurred as the growth-strain method was applied to multi-connected structures were examined, and then the improved method was suggested. The effectiveness and practicality of the developed shape optimization system was verified by numerical examples.

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Shape Optimization of Structures with a Crack (균열이 있는 구조물의 형상 최적화)

  • 한석영;송시엽;백춘호
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.298-303
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    • 2001
  • Most of mechanical failures are caused by repeated loadings and therefore they are strongly related to fatigue. To avoid the failures caused by fatigue, determination of an optimal shape of a structure is one of the very important factors in the initial design stage. Shape optimization for a compact tension specimen in opening mode in fracture mechanics, was accomplished by the linear elastic fracture mechanics and the growth-strain method in this study. Also shape optimization for a cantilever beam in mixed mode was carried out by the same techniques. The linear elastic fracture mechanics was used to estimate stress intensity factors and fatigue lives. And the growth-strain method was used to optimize the shape of the initial shape of the specimens. From the results of the shape optimization, it was found that shapes of two types of specimens and a cantilever beam optimized by the growth-strain method prolong their fatigue lives very much. Therefore, it was verified that the growth-strain method is an appropriate technique for shape optimization of a structure having a crack.

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A Study on the Modification of a Finite Element for Improving Shape Optimization (형상최적화 향상을 위한 유한요소의 개선에 관한 연구)

  • Sung, Jin-Il;Yoo, Jeong-Hoon
    • Proceedings of the KSME Conference
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    • pp.367-371
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    • 2001
  • In the shape optimization based on the finite element method, the accuracy of finite element analysis of a given structure is important to determine the final shape. In case of a bending dominant problem, finite element solutions by the full integration scheme are not reliable because of the locking phenomenon. Furthermore, in the process of shape optimization, the mesh distortion is large due to the change of the structure outline: therefore, we cannot guarantee the accurate result unless the finite element itself is accurate. We approach to more accurate shape optimization to diminish these inaccuracies by improving the existing finite element. The shape optimization using the modified finite element is applied to a two-dimensional simple beam. Results show that the modified finite element have improved the optimization results.

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Development of Shape Optimization System for General Structures (일반 구조물에 대한 형상 최적화 시스템의 개발)

  • 한석영
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.304-309
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    • 2000
  • Growth-strain method was used for shape optimization of general structures. It was verified that the growth-strain method is very effective for shape optimization of solid structures in previous papers, but It could not provide reasonable optimized shape for structures with holes inside. The purpose of this study is to improve the growth-strain method for shape optimization of two- and three- dimensional structures. In order to improve, the problems occurred as the growth-strain method was applied to general structures were examined, and then the improved method was suggested. Finally, an automatic shape optimization system was built up by the improved growth-strain method with finite element method. The effectiveness and practicality of the developed shape optimization system was verified by some examples.

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Reliability-based Shape Optimization Using Growth Strain Method (성장-변형률법을 이용한 신뢰성 기반 형상 최적화)

  • Oh, Young-Kyu;Park, Jae-Yong;Im, Min-Gyu;Park, Jae-Yong;Han, Seog-Young
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.5
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    • pp.637-644
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    • 2010
  • This paper presents a reliability-based shape optimization (RBSO) using the growth-strain method. An actual design involves uncertain conditions such as material property, operational load, Poisson's ratio and dimensional variation. The purpose of the RBSO is to consider the variations of probabilistic constraint and performances caused by uncertainties. In this study, the growth-strain method was applied to shape optimization of reliability analysis. Even though many papers for reliability-based shape optimization in mathematical programming method and ESO (Evolutionary Structural Optimization) were published, the paper for the reliability-based shape optimization using the growth-strain method has not been applied yet. Growth-strain method is applied to performance measure approach (PMA), which has probabilistic constraints that are formulated in terms of the reliability index, is adopted to evaluate the probabilistic constraints in the change of average mises stress. Numerical examples are presented to compare the DO with the RBSO. The results of design example show that the RBSO model is more reliable than deterministic optimization. It was verified that the reliability-based shape optimization using growth-strain method are very effective for general structure. The purpose of this study is to improve structure's safety considering probabilistic variable.

A Study on the Improvement of Shape Optimization associated with the Modification of a Finite Element (유한요소의 개선에 따른 형상최적화 향상에 관한 연구)

  • Sung, Jin-Il;Yoo, Jeong-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1408-1415
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    • 2002
  • In this paper, we investigate the effect and the importance of the accuracy of finite element analysis in the shape optimization based on the finite element method and improve the existing finite element which has inaccuracy in some cases. And then, the shape optimization is performed by using the improved finite element. One of the main stream to improve finite element is the prevention of locking phenomenon. In case of bending dominant problems, finite element solutions cannot be reliable because of shear locking phenomenon. In the process of shape optimization, the mesh distortion is large due to the change of the structure outline. So, we have to raise the accuracy of finite element analysis for the large mesh distortion. We cannot guarantee the accurate result unless the finite element itself is accurate or the finite elements are remeshed. So, we approach to more accurate shape optimization to diminish these inaccuracies by improving the existing finite element. The shape optimization using the modified finite element is applied to a two and three dimensional simple beam. Results show that the modified finite element has improved the optimization results.

Shape Optimization of a Thomson coil Actuator of Arc Eliminator Using Topology Modification (Topology Modification을 이용한 Thomson coil Actuator의 형상 최적화)

  • Li, Wei;Jeong, Young-Woo;Koh, Chang-Seop
    • Proceedings of the KIEE Conference
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    • pp.774_775
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    • 2009
  • The shape optimization of a Thomson coil actuator used in an arc eliminator is done for fast response by adopting topology modification method. The performance of the actuator is analyzed by using an equivalent circuit method. Both shape optimization and performance analysis are accomplished based on the segmentation of plate. The effectiveness of the proposed method is proved by the comparison of results before and after the shape optimization.

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Shape Optimization for Reinforced Concrete Culvert (철근콘크리트 암거의 형상 최적화)

  • Kim, Kee-Dae
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.3
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    • pp.261-268
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    • 2002
  • In this paper, the shape optimization is considered over the upper slab of reinforced concrete culvert. The sequential linear programming method (SLP) is used as a rational approach to this shape optimization. To make a comparison between the arch shaped member and the straight member for the upper slab, the culverts with 5~20m earth height were adopted. It is shown that the optimum rise/span is about 7%-13%, and the arch shaped member is more cheap (over 10%) than the straight member for the construction cost.

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