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이중석(Joong Seok Lee),김재은(Jae Eun Kim),김윤영(Yoon Young Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The topology design method has been introduced for structural damage identification. The resonances and antiresonances of the finite element models corresponding to damaged and undamaged structures are used as the predominant parameters in the developed topology optimization based damage identification method. The keys to the success of the topology optimization in damage identification are 1) the use of both resonances and antiresonances and 2) the non-conventional topology optimization formulation newly developed for damage identification applications. To pinpoint minor damage locations, a multi-stage candidate damage location identification scheme, which is called the progressive design variable reduction scheme, is also developed. Several numerical tests were performed to show the effectiveness and accuracy of the proposed method.
흡음성능 향상을 위해 위상최적설계기법을 이용한 흡음재의 최적형상 설계
이중석(Joong Seok Lee),김윤영(Yoon Young Kim),김정수(Jung Soo Kim),강연준(Yeon June Kang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Topology optimization formulation for the optimal shape design of poroelastic acoustical foams is studied to maximize its absorption coefficient. The acoustical system in consideration consists of two different physical regions: an air region and a poroelastic foam region. To account for the changes between the two regions in an iterative optimization, we adopted the unified multiphase analysis method which is based on Biot's equations with a material property interpolation technique. The unified multiphase analysis method can express an air region as well as a poroelastic foam region with the same governing equation. With the method, we carried out an optimal shape design of a poroelastic acoustical foam in a topology optimization setting. The objective was the maximization of the absorption coefficient in low and middle ranges of frequencies. Compared with a well-known wedge shape, the optimized foam shape showed significant improvement in the absorption performance in the target range of frequencies.
흡음을 위한 다공성 물질의 최적형상설계에서 물성치의 영향
이중석(Joong Seok Lee),김윤영(Yoon Young Kim),강연준(Yeon June Kang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
This investigation studies the effects of material properties and corresponding propagation wave types on optimal configurations of sound absorbing porous materials in maximizing the absorption performance by topology optimization. The acoustic behavior of porous materials is characterized by their material properties which determine motions of the frame and the air. When the frame has a motion, two types of compressional wave propagate in the porous material. Because each wave in the material make different influence on the absorption performance, it is important to understand the relative contribution of each wave to the sound absorption. The relative contribution of the propagating waves in a porous material is determined by the material properties, therefore, an optimal configuration of a porous material to maximize the absorption performance is apparently affected by the material properties. In fact, virtually different optimal configurations were obtained for absorption coefficient maximization when the topology optimization method developed by the authors was applied to porous materials having different material properties. In this investigation, some preliminary results to explain the findings are presented. Although several factors should be considered, the present investigation is focused on the effects of the material properties and corresponding propagation waves on the optimized configurations.
구조물의 결함 규명을 위한 위상최적설계 기법의 적용가능성 연구
이중석(Lee, Joong-Seok),김재은(Kim, Jae-Eun),김윤영(Kim, Yoon-Young) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.2
A feasibility of using the topology optimization method for structural damage identification is investigated for the first time. The frequency response functions (FRFs) are assumed to be constructed by the finite element models of damaged and undamaged structures. In addition to commonly used resonances, antiresonances are employed as the damage identifying modal parameters. For the topology optimization formulation, the modal parameters of the undamaged structure are made to approach those of the damaged structure by means of the constraint equations, while the objective function is an explicit penalty function requiring clear black-and-white images. The developed formulation is especially suitable for damage identification problems dealing with many modal parameters. Although relatively simple numerical problems were considered in this investigation, the possibility of using the topology optimization method for structural damage identification is suggested through this research.