• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.1
• /
• pp.69-74
• /
• 2007

Topology optimization of the inner reinforcement for a vehicle's hood has been performed by evolutionary structural optimization(ESO) using a smoothing scheme. The purpose of this study is to obtain optimal topology of the inner reinforcement for a vehicle's hood considering the static stiffness of bending and torsion simultaneously. To do this, the multiobjective optimization technique was implemented. Optimal topologies were obtained by the ESO method. From several combinations of weighting factors, a Pareto-optimal solution was obtained. Also, a smoothing scheme was implemented to suppress the checkerboard pattern in the procedure of topology optimization. It is concluded that ESO method with a smoothing scheme is effectively applied to topology optimization of the inner reinforcement of a vehicle's hood considering the static stiffness of bending and torsion.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.5
• /
• pp.589-595
• /
• 2010

This paper presents a reliability-based shape optimization (RBSO) using the evolutionary structural optimization (ESO). An actual design involves uncertain conditions such as material property, operational load, poisson's ratio and dimensional variation. The deterministic optimization (DO) is obtained without considering of uncertainties related to the uncertainty parameters. However, the RBSO can consider the uncertainty variables because it has the probabilistic constraints. In order to determine whether the probabilistic constraint is satisfied or not, simulation techniques and approximation methods are developed. In this paper, the reliability-based shape design optimization method is proposed by utilization the reliability index approach (RIA), performance measure approach (PMA), single-loop single-vector (SLSV), adaptive-loop (ADL) are adopted to evaluate the probabilistic constraint. In order to apply the ESO method to the RBSO, a sensitivity number is defined as the change of strain energy in the displacement constraint. 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.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.533-538
• /
• 1997

Topology optimization of a concrete structure is discussed using an Evolutionary Structural Optimization(ESO) method introduced by Xie and Steven. During the evolution process low stressed materials are progressively removed from the structure. This paper discussed a proper rejection criterion(RC) to get a more reasonable topology of concrete structure. Some examples are presented to illustrate the optimum topology achieved by such a procedure.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.6
• /
• pp.77-82
• /
• 2008

This paper presents a Reliability-Based Topology Optimization(RBTO) using the Evolutionary Structural Optimization(ESO). An actual design involves some uncertain conditions such as material property, operational load and dimensional variation. The Deterministic Topology Optimization(DTO) is obtained without considering the uncertainties related to the uncertainty parameters. However, the RBTO can consider the uncertainty variables because it has the probabilistic constraints. In order to determine whether the probabilistic constraints are satisfied or not, simulation techniques and approximation methods are developed. In this paper, the reliability index approach(RIA) is adopted to evaluate the probabilistic constraints. In order to apply the ESO method to the RBTO, sensitivity number is defined as the change in the reliability index due to the removal of the ith element. Numerical examples are presented to compare the DTO with the RBTO.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.46-51
• /
• 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. .

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.360-364
• /
• 2001

본 논문에서는 최근의 진화적 구조최적화(ESO) 전략을 회전축의 형상최적화에 적용하였으며, 각 계산 스텝마다 단위 유한요소의 크기를 변경함으로써 기존의 방법보다 빠르고 정확한 최적형상에 수렴하는 새로운 방법을 제시하였다. 축요소의 직경을 시스템 설계변수로 하였으며, 축중량의 감소, 공진배율(Q-factor)의 감소 및 충분한 위험속도의 분리여유를 갖도록 목적함수를 설정하였다. 불평형응답 및 굽힙응력의 구속조건을 부가하였으며, 목적함수에 대한 설계변수의 감도해석을 수행하였다. 전동기축계에 대한 적용 결과로부터 주파수와 동적 구속조건하의 로터베어링 시스템에 대한 축 형상 최적화에 ESO법이 효과적으로 이용될 수 있음을 확인하였다.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.1
• /
• pp.47-52
• /
• 2007

A material mixing method to obtain an optimal topology for a structure in a thermal environment was suggested. This method is based on Evolutionary Structural Optimization(ESO). The proposed material mixing method extends the ESO method to a mixing several materials for a structure in the multicriteria optimization of thermal flux and thermal stress. To do this, the multiobjective optimization technique was implemented. The overall efficiency of material usage was measured in terms of the combination of thermal stress levels and heat flux densities by using a combination strategy with weighting factors. Also, a smoothing scheme was implemented to suppress the checkerboard pattern in the procedure of topology optimization. It is concluded that ESO method with a smoothing scheme is effectively applied to topology optimization. Optimal topologies having multiple thermal criteria for a printed circuit board(PCB) substrate were presented to illustrate validity of the suggested material mixing method. It was found that the suggested method works very well for the multicriteria topology optimization.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.10a
• /
• pp.259-264
• /
• 2003

This paper suggests a material mixing method to mix several materials in a structure. This method is based on ESO(Evolutionary Structural Optimization), which has been used to optimize topology of only one material structure. In this study, two criterions for material transformation and element removal are implemented for mixing several materials in a structure. Optimal topology for a multiple material structure can be obtained through repetitive application of the two criterions at each iteration. Two practical design examples of a short cantilever are presented to illustrate validity of the suggested material mixing method. It is found that the suggested method works very well and a multiple material structure has more stiffness than one material structure has under the same mass.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.53 no.6
• /
• pp.153-163
• /
• 2011

This research describe improved algorithm that is able to decide terminal criterion of Evolutionary Structural Optimization (ESO), reducing load of calculation to search load path of concrete beam, and apply to agricultural facilities. The ESO method is that make to discrete structure, structural analyze each element stress through FEM. And repeat generation with next material condition to become for most suitable composing. Individual element introduces concept of zero stiffness, but zero stiffness decisions are gone to direction of exclusion. In this stduy, improve algorithm to be convergence by 'Rule of Alive or Die' in arrival because is most suitable. Also, existing terminal criterion lack consistency because that used depend on experience of researcher. This research procedure is fellowed. First, all modulus of elasticity assume a half of elasticity modulus of material, Second, structural analysis by FEM, Third, apply to the remove ratio and restoration ratio for the 'rule of alive or die'. Forth, reconstruct the element and material conditions. And repeat the first to forth process. The terminal time of evolutional procedure is the all elastic modulus of element changed to blank value or elasticity modulus value of original. Therefore, in this study, consist the algorithm for programming, and apply to the agricultural facilities with concrete.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.6
• /
• pp.726-731
• /
• 2004

This paper suggests a material mixing method to mix several materials in a structure. This method is based on ESO(Evolutionary Structural Optimization), which has been used to optimize topology of only one material structure. In this study, two criterions for material transformation and element removal are implemented for mixing several materials in a structure. Optimal topology for a multiple material structure can be obtained through repetitive application of the two criterions at each iteration. Two practical design examples of a short cantilever are presented to illustrate validity of the suggested material mixing method. It is found that the suggested method works very well and a multiple material structure has more stiffness than one material structure has under the same mass.