• 대한기계학회논문집A
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• 제30권8호
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• pp.889-896
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• 2006

The concept of reliability has been applied to the topology optimization based on a reliability index approach or a performance measure approach. Since these approaches, called double-loop single vector approach, require the nested optimization problem to obtain the most probable point in the probabilistic design domain, the time for the entire process makes the practical use infeasible. In this work, new reliability-based topology optimization method is proposed by utilizing single-loop single-vector approach, which approximates searching the most probable point analytically, to reduce the time cost. The results of design examples show that the proposed method provides efficiency curtailing the time for the optimization process and accuracy satisfying the specified reliability.

• 한국전산구조공학회논문집
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• 제23권1호
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• pp.37-43
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• 2010

본 논문에서는 선형 구조물에 대해 성능함수법을 이용하여 신뢰성기반 위상 최적설계 기법을 개발하였다. 구조물을 라이즈너-민들린(Ressiner-Mindlin) 판 요소로 분할하였으며, 각 요소의 재료 물성치를 설계변수로 사용하였다. 설계변수와 임의변수의 효율적인 설계민감도를 구하기 위하여 연속체 역학에 기초한 해석기법 중 보조변수법(Adjont variable method)을 사용하였다. 또한 확률론적 제약조건을 평가하기 위해서 성능함수법(Performance measure approach)을 사용하였으며 변위 제약조건을 두어 위상 최적설계 문제를 구성하였다. 이 때 재료 물성치와 하중을 불확실 변수로 고려하였으며 수치적 예제를 통하여 본 논문에서 제안한 최적설계 방법론을 기존의 결정론적 방법, 안전계수법(Safety factor approach), 최악조건법(Worst case approach) 등과 비교하여 그 타당성을 검증하였다.

• 한국생산제조학회지
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• 제19권6호
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• pp.826-833
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• 2010

Electric-thermal-structural actuated compliant mechanisms are mechanisms onto which electric voltage drop is applied as input instead of force. This mechanism is based on thermal expansion of material while being heated. Compliant mechanisms are designed subjected to electric charge input using BESO(bi-directional evolutionary structural optimization) method. Reliability-based topology optimization (RBTO) is applied to the topology design of actuators. 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 this study, BESO method is used to obtain optimal topology of compliant mechanisms from initial design domain. PMA approach is used to evaluate reliability index. The procedure has been tested in numerical applications and compared with the results obtained by other methods to validate these approaches.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.77-82
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• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.741-743
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• 2003

A reliability-based topology optimization (RBTO) for electromagnetic systems using the finite element method is presented. Permeability and applied current density are considered as uncertain variable. In order to compute reliability constraints, performance measure approach is used. To find the reliability index, the limit state function is linearly approximated at each iteration. Numerical examples show the effectiveness of the proposed method.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.123-130
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• 2004

The automobile suspension system is composed of parts that affect performances of a vehicle such as ride quality, handling characteristics, straight performance and steering effort, etc. Moreover, by using the finite element analysis the cost for the initial design step can be decreased. In the design of a suspension system, usually system vibration and structural rigidity must be considered simultaneously to satisfy dynamic and static requirements simultaneously. In this paper, we consider the weight reduction and the increase of the first eigen-frequency of a suspension part, the upper control arm, especially using topology optimization and size optimization. Firstly, we obtain the initial design to maximize the first eigen-frequency using topology optimization. Then, we apply the multi-objective parameter optimization method to satisfy both the weight reduction and the increase of the first eigen-frequency. The design variables are varying during the optimization process for the multi-objective. Therefore, we can obtain the deterministic values of the design variables not only to satisfy the terms of variation limits but also to optimize the two design objectives at the same time. Finally, we have executed reliability based optimal design on the upper control arm using the Monte-Carlo method with importance sampling method for the optimal design result with 98％ reliability.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.719-727
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• 2021

건축 분야는 최근 기계·로봇 분야와 접목하여 환경에 유동적으로 대응할 수 있는 개폐식 장치를 경기장과 같은 대공간 구조물의 지붕에 많이 적용하고 있다. 이러한 장치 중에서 외관이 수려한 개폐 막은 경량이어서 경계부의 견인 장치만으로 막을 쉽게 개폐할 수 있다. 그러나 막은 주 케이블에 트롤리로 연결되어 이동하므로 지붕의 면적에 비례해 트롤리 개수가 늘어난다. 본 연구에서는 이러한 막의 개폐 장치에 많이 사용되는 오픈형 트롤리를 위상 최적 기법을 이용하여 모델을 제안한다. 해석은 ANSYS 프로그램을 사용하였고, 결과를 바탕으로 피드백 과정을 통해서 새로운 모델을 제안하고, 검토하였다. 이 과정에서 트롤리 중량은 줄고, 내구성이 높아진 원형을 개발할 수 있었다. 오픈형 트롤리는 정적 해석 결과와 이에 대한 경계조건을 바탕으로 위상 최적화를 수행하며, 세 가지 타입의 최적 트롤리 원형을 설계하였다. 제안된 트롤리는 기본형 트롤리와 같은 조건에서 비교한 결과, 최대 71.04%의 부피를 감소시켰고, 항복강도는 8.67~11.43%에 달하였다. 결론적으로 본 연구에서 제안된 최적화 트롤리 모델은 경제성과 안정성을 신뢰할 만하였다.