• Title/Summary/Keyword: Element Removal Method

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Comparative Study on Element Removal Methods for ESO (진화적 구조 최적화를 위한 요소 제거법의 비교 연구)

  • 한석영
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.5
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    • pp.112-118
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    • 2000
  • In case ESO(evolutionary structural optimization) which is one of topology optimization methods, the element removal ratio is fixed throughout topology optimization by 1 or 2%. As a result it has no flexibility for various types of structures and thus the rate of convergence might not be efficient. Thus various element removal methods were developed in order to improve the efficiency of ESO. In this paper, various element removal methods for ESO are compared with each other for a bracket and a short cantilever. In addition, a new improved bi-directional element removal method is suggested in order to obtain much better optimized topology. From the comparative results of the examples, it is verified that all of the developed various element removal methods are very effective, and the suggested element removal method is the most effective.

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Effective Element Removal Methods for Topology Optimization (위상 최적화를 위한 효율적인 요소 제거법)

  • 한석영
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.04a
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    • pp.46-51
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    • 2000
  • In case of ESO(evolutionary structural optimization) which is one of topology optimization methods, the element removal ratio is fixed throughout topology optimization by 1 or 2 %. As a result it has no flexibility for various types of structures and thus the rate of convergence might not be efficient. Thus various element removal methods are developed in order to improve the efficiency of ESO. In this paper, various element removal methods for ESO are compared with each other. Each element removal method is explained, and applied to a bracket and a Michell type of beam. In addition, a new bi-directional element removal method is suggested in order to obtain much better optimized topology. From the results of stress, displacement and the rate of convergence for the examples under the same mass constraints, it is verified that the suggested element removal method is the most effective. .

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An Improved Element Removal Method for Evolutionary Structural Optimization

  • Han, Seog-Young
    • Journal of Mechanical Science and Technology
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    • v.14 no.9
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    • pp.913-919
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    • 2000
  • The purpose of this study was to develop a new element removal method for ESO (Evolutionary Structural Optimization), which is one of the topology optimization methods. ESO starts with the maximum allowable design space and the optimal topology emerges by a process of removal of lowly stressed elements. The element removal ratio of ESO is fixed throughout topology optimization at 1 or 2%. BESO (bidirectional ESO) starts with either the least number of elements connecting the loads to the supports, or an initial design domain that fits within the maximum allowable domain, and the optimal topology evolves by adding or subtracting elements. But the convergence rate of BESO is also very slow. In this paper, a new element removal method for ESO was developed for improvement of the convergence rate. Then it was applied to the same problems as those in papers published previously. From the results, it was verified that the convergence rate was significantly improved compared with ESO as well as BESO.

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Finite Element Prediction of Deformation of Material due to Springback after Material Removal of a Forging (단조 후 소재 절삭에 따른 탄성회복 변형의 유한요소예측)

  • Joun, M.S.;Chung, W.J.;Jeong, S.W.
    • Transactions of Materials Processing
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    • v.26 no.4
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    • pp.205-209
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    • 2017
  • In this paper, finite element prediction of deformation of material due to springback after material removal by an axisymmetric forging fabrication at room temperature is conducted. An elastoplastic finite element method is employed considering die plastic deformation. The predictions of a springback analysis conducted after the final stroke of an axisymmetric cold forging process containing residual stresses are utilized to be mapped onto the final material after the material removal. It is assumed that material removal occurs at an instant, i.e., all the material to be removed disappears at once. The predictions are compared with experiments, revealing strong qualitative agreement.

Study on Shape Optimization Using Finite Elements Addition and Removal (요소가감법을 이용한 형상최적설계에 관한 연구)

  • Kim, Young-Jin;Lim, Kyeong-Ho
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.486-491
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    • 2000
  • In this study, finite elements addition and removal method by stress range is applied to optimize shapes in structures, without using classical and numerical optimization methods and search methods. The program based on this algorithm is developed and compared to theoritial results with considerable accuracy. Classical methods need mesh generation for finite element analysis for every iteration, the developed method needs updated mesh data such as coordinates of nodes, elements connectivity, and loads on nodes. And other tools of finite element analysis can be in use as a black box to interface with this program.

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Topology Optimization of Element Removal Method Using Stress Density (응력량을 이용한 요소제거법의 위상최적화)

  • 임오강;이진식;김창식
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.16 no.1
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    • pp.1-8
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    • 2003
  • Topology optimization has been evolved into a very efficient conceptual design tool and has been utilized into design engineering processes. Traditional topology optimization has been using homogenization method and optimality criteria method. homogenization method provides relationship equation between structure which includes many holes and stiffness matrix in FEM. Optimality criteria method is used to update design variables while maintaining that volume fraction is uniform. Traditional topology optimization has advantage of good convergence but has disadvantage of too much convergency time. In one way to solve this problem, element removal method using the criterion of an average stress is presented. As the result of examples, it is certified that convergency time is very reduced.

Study on Within-Wafer Non-uniformity Using Finite Element Method (CMP 공정에서의 웨이퍼 연마 불균일성에 대한 유한요소해석 연구)

  • Yang, Woo Yul;Sung, In-Ha
    • Tribology and Lubricants
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    • v.28 no.6
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    • pp.272-277
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    • 2012
  • Finite element analysis was carried out using wafer-scale and particle-scale models to understand the mechanism of the fast removal rate(edge effect) at wafer edges in the chemical-mechanical polishing process. This is the first to report that a particle-scale model can explain the edge effect well in terms of stress distribution and magnitude. The results also revealed that the mechanism could not be fully understood by using the wafer-scale model, which has been used in many previous studies. The wafer-scale model neither gives the stress magnitude that is sufficient to remove material nor indicates the coincidence between the stress distribution and the removal rate along a wafer surface.

Numerical Study of Inclusion removal from Molten Steel by Argon Gas Flotation (용강 내 아르곤가스의 개재물 흡착에 대한 수치적 연구)

  • 문창호;황상무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.335-338
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    • 2003
  • A finite element-based, integrated process model has been developed and applied to predict the detailed, three-dimensional aspects of the thermo-mechanical behavior occurring in the slab caster considering inclusion removal from molten steel by argon bubble flotation. Gas bubbles are simulated using the dispersion model calculating the volume fraction, and the bubble capture effect is included by a source term in the transport equation for particles. The process model is applied to the investigation of the effect of various process parameters on the inclusion removal in the molten steel.

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Analysis of Underground Box Structures with Inelastic Soil Spring (비탄성 지반 스프링을 이용한 지하 구조물의 해석)

  • Oh, Chi-Woong;Chung, Jae-Hoon;Yhim, Sung-Soon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.3
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    • pp.91-96
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    • 2002
  • There are many methods for analyzing underground box structures. One is the method of Iterative removal of tensional spring. The other is the method of modeling of ground to 8-node elastic-plastic planar element. In this study, We use inelastic soil spring element for analyzing underground box structures. First, if N-value is over 50, the results of inelastic soil spring method is the same as the method of 8-node planar element in last stage. Second, as N is increasing, element forces in two methods are generally decreasing. Third, as N-value is increasing, element forces in two method are generally decreasing and displacement has decreasing incline. This is the same as the force-displacement curve of general underground structures.

REMOVAL TORQUE OF BICORTICALLY STABILIZED RBM(RESORBABLE BLAST MEDIA) PIN IMPLANTS IN RABBIT TIBIA

  • Kim, Kwon-Sik;Suh, Kyu-Won;Lee, Richard Sung-Bok;Ryu, Jae-Jun
    • The Journal of Korean Academy of Prosthodontics
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    • v.44 no.6
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    • pp.722-733
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    • 2006
  • Statement of problem. The use of small diameter implants having less than 3 mm in diameter were restricted because of lack of bonding strength to bone. Purpose. The purpose of this study was to observe how much resorbable blast media pin implants increase the binding force to the bone compared to machined transitional pin implants by measuring removal torque, and whether they can be used as final implants for replacement of small diameter teeth. Material and method. Fifteen rabbits were used in this study. Two kinds of implants (resorbable blast media pin implants and machined transitional pin implants) were inserted in each tibia bicortically. After healing time of 2, 4 and 8 weeks, the removal torque values were recorded and the rabbits were sacrificed for histological analysis. Linear finite element method analyses were conducted to compare bicortical fixation with monocortical fixation. Result and conclusion. Within the limitation of this in vivo study, the following conclusions were drawn: 1) The removal torque value of RBM pin implants showed statistically significant increase compared to machined pin implants at 2, 4, and 8 weeks respectively (p<0.05). 2) The removal torque value of RBM pin implants at 2, 4, and 8 weeks was increased statistically significantly with time (p<0.05). 3) Bicortical fixation showed better stress distribution compared with monocortical fixation in a linear finite element method analysis. 4) RBM pin implants are not recommended as transitional implants because they showed a lot of bone fracture in histologic specimens.