• Title, Summary, Keyword: Shape optimization

Search Result 1,572, Processing Time 0.043 seconds

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
    • /
    • v.8 no.2
    • /
    • pp.27-34
    • /
    • 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.

  • PDF

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
    • /
    • /
    • pp.304-309
    • /
    • 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.

  • PDF

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

  • 한석영;배현우
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.8 no.2
    • /
    • pp.151-158
    • /
    • 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.

  • PDF

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
    • /
    • v.26 no.7
    • /
    • pp.1408-1415
    • /
    • 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.

A Study on the Shape Optimal Design of a Bogie Frame for the Reduction of its Weight (대차프레임의 중량감소를 위한 형상최적설계에 관한 연구)

  • 조우석;최경호;박정호;안찬우;김현수
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • /
    • pp.616-619
    • /
    • 2000
  • The optimum design of a structure requires to determine economical member size and shape of a structure which satisfies the design conditions and functions. In this study, it is attempted to minimize a dead weight of the bogie frame. Therefore, shape optimization is performed for a bolster rib at first and then size optimization for the thickness of top and bottom plate. For the efficient reduction of a weight of a bogie frame, various ellipses centered at a centroid of a bolster rib are made and tried. For the shape optimization, a major axis and an eccentricity of an ellipse are chosen as design variables. From the numerical results of shape and size optimization of a bogie frame, it is known that the weight can be reduced up to 12.476 Y4717.21 kg) with displacement and stress constraints.

  • PDF

About the Shape Optimization of Ex-Manifold Diffuser (배기 매니폴드 확관부 형상 최적화에 관하여)

  • Jo, Sok-Hyun
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.28 no.9
    • /
    • pp.1133-1138
    • /
    • 2004
  • Shape optimization method was coupled with a conventional CFD analysis to find the optimal shape of ex-manifold diffuser which decreases the maldistribution of flow above the catalyst. Shape optimization results show that flow uniformity above the catalyst was increased about 28% fur the axi-symmetric case and about 18% for the asymmetric case. The axi-symmetric type can be applied to the diffuser of under floor catalyst and the asymmetric type can be applied to the diffuser of close coupled catalyst.

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
    • /
    • /
    • pp.277-280
    • /
    • 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.

  • PDF

Structural design using topology and shape optimization

  • Lee, Eun-Hyung;Park, Jaegyun
    • Structural Engineering and Mechanics
    • /
    • v.38 no.4
    • /
    • pp.517-527
    • /
    • 2011
  • A topology optimization and shape optimization method are widely used in the design area of engineering field. In this paper, a unified procedure to combine both topology and shape optimization method is used. A material distribution method is used first to extract necessary design parameters of the structure and a shape optimization scheme using genetic algorithm and satisfying all the condition follows. As an example, a GFRP bridge deck is designed and compared with other commercial products. The performance of the designed deck shows that the used design procedure is very efficient and safe. This procedure can be generalized for using in other areas of engineering.

Shape Optimization for Prolonging Fatigue Life of a Structure (구조물의 피로수명 향상을 위한 형상 최적화)

  • Han, Seok-Yeong;Song, Si-Yeop
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.26 no.8
    • /
    • pp.1512-1519
    • /
    • 2002
  • 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 fer two types of specimens, which are very typical ones 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 significantly. Therefore, it was verified that the growth-strain method is an appropriate technique for shape optimization of a structure having a crack.

Structural Shape Optimization under Static Loads Transformed from Dynamic Loads (동하중으로부터 변환된 등가정하중을 통한 구조물의 형상최적설계)

  • Park, Ki-Jong;Lee, Jong-Nam;Park, Gyung-Jin
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.1262-1269
    • /
    • 2003
  • In structural optimization, static loads are generally utilized although real external forces are dynamic. Dynamic loads have been considered in only small-scale problems. Recently, an algorithm for dynamic response optimization using transformation of dynamic loads into equivalent static loads has been proposed. The transformation is conducted to match the displacement fields from dynamic and static analyses. The algorithm can be applied to large-scale problems. However, the application has been limited to size optimization. The present study applies the algorithm to shape optimization. Because the number of degrees of freedom of finite element models is usually very large in shape optimization, it is difficult to conduct dynamic response optimization with the conventional methods that directly threat dynamic response in the time domain. The optimization process is carried out via interfacing an optimization system and an analysis system for structural dynamics. Various examples are solved to verify the algorithm. The results are compared to the results from static loads. It is found that the algorithm using static loads transformed from dynamic loads based on displacement is valid even for very large-scale problems such as shape optimization.

  • PDF