• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.118-123
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• 1996

The purpose of this study is to develop acoustic substructure synthesis method that can be applied to acoustic modal analysis of complex acoustic systems. Acoustic modal analysis method to be introduced here is a method that analyze acoustic natural mode shape of the complex acoustic system by the principle of CMS(component mode synthesis method). This paper describes the acoustic modal analysis of the acoustic finite element model of simple expansion pipe by acoustic substructure synthesis method. The results of acoustic modal analysis analyzed by Acoustic substructure synthesis method and the results, by FEM(finite element method) shows good agreement.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.874-880
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• 2003

Many mechanical systems are over-constrained if only rigid bodies are used to model the system. One example of such system is a satellite system with solar panels. To avoid this over-constrained problem, solar panels can be modeled as flexible bodies. The CMS(Component Mode Synthesis) method is widely used to analyze the flexible multi-body system because it can considerably approximate the deformation of the flexible bodies using small number of well-selected mode. However, it is very difficult to decide the boundary condition and the selection of modes. In this paper, the methods for mode synthesis and setting the boundary condition are presented to analyze the flexible multi-body system with over-constraints. Finally, the reliability of proposed method is verified by solar panel's deployment test.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.852-855
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• 2005

Structural Dynamic Modification(SDM) is a technique to improve structure's dynamic characteristics by adding and removing substructures or changing material properties and shape of structures. This paper describes SDM techniques applied to a large structure with too many DOFs. The goal of this SDM technique is to modify a targe structure efficiently for its natural frequencies to avoid excitation frequencies. In this case, models reduced by Component Mode Synthesis(CMS) method that is a coupling technique are used to analyze a large structure efficiently. This paper considers a helicopter deck model with 55,000 DOFs as an application.

• 대한기계학회논문집A
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• 제25권3호
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• pp.495-501
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• 2001

In this paper, a new technique which models the joints characteristics through reduction of DOFs of structures with joints using component mode synthesis (CMS) method is proposed. Bolt joints are modeled by mass-spring systems. Also generalized mass and stiffness matrices for this models are introduced. Because bolt joints have influence on eigenvalues of structures, exact eigenvalues from modal test are used. The results show that the behaviors of structures with bolt joints depend to a large extent on the translational DOFs and not on rotational DOFs of mass and stiffness matrices of bolts. Furthermore it is confirmed that lumped mass-spring systems as models of bolt joints are effective models considering the facts that joint characteristics converged to constant values in some iterations and eignevalues from proposed method are in good agreement with ones from modal test.

• 대한기계학회논문집A
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• 제34권5호
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• pp.519-525
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• 2010

승용 차량과 항공기와 같은 대형 구조물에 대한 해석에는 유한요소법이 일반적으로 사용되고 있다. 그러나 대형 구조물을 유한요소로 모델화 하여 해석하는 경우에는 자유도의 수가 수천에서 수만에 이르게 되어 이를 직접 해석하기 위해서는 많은 시간과 노력이 필요하다. 따라서 차량 모델과 같은 대형 복잡 구조물을 효율적으로 해석하기 위해 부분구조 합성법이 많이 사용되고 있다. 본 연구에서는 Craig-Bampton 방법을 이용한 전차량 모델링 방법을 제안하고 전차량 모델의 진동 특성을 분석하였다. 차량 모델을 구성하는 각 부분을 각각 부분구조 모델로 치환한 후 다시 합성하여 전차량 모델을 구성하였다. 또한, 서브프레임 주요 설계변수, 즉 마운트 위치나 프레임 크기의 편차가 전체 시스템의 모드 특성의 통계적 변화에 미치는 영향을 살펴보았다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.830-833
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• 2005

SDM(Structural Dynamics Modification) is to improve dynamic characteristics of a structure, more specifically of a base structure, by adding or deleting auxiliary(modifying) structures. In this paper, I will focus on the optimal layout of the stiffeners which are attached to the plate to maximize 1st natural frequency. Recently, a new topology method was proposed by yamazaki. He uses growing and branching tree model. I modified the growing and branching tree model. The method is designated modified tree model. To expand the layout of stiffeners, I will consider non-matching problem. The problem is solved by using local lagrange multiplier without the mesh regeneration. Moreover The CMS(Component mode synthesis) method is employed to reduce the computing time of eigen reanalysis using reduced componet models.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.735-741
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• 2011

In the early phase of vehicle development, CAE is conducted as tool for vehicle performance assessment. To maintain acceptable road noise performance, solution for reduced vehicle sensitivity is required. Chassis interface dynamic stiffness characteristics are key component to isolating vibration and noise of road from the vehicle interior. This research provide how to set up the optimized dynamic characteristics under noise effect through DFSS study. CAE-based DOE is performed to build prediction math model, CMS process involves DOE to achieve very fast run times while giving results very comparable. Minimized $95^{th}$ percentile of performance distribution is applied to minimize vehicle sensitivity and road noise levels variation during the optimization process. Finally, the results of optimization were reviewed for performance and robustness.

• 한국소음진동공학회논문집
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• 제21권7호
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• pp.674-681
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• 2011

In the early phase of vehicle development, CAE is conducted as tool for vehicle performance assessment. To maintain acceptable road noise performance, solution for reduced vehicle sensitivity is required. Chassis interface dynamic stiffness characteristics are key component to isolating vibration and noise of road from the vehicle interior. This research provide how to set up the optimized dynamic characteristics under noise effect through DFSS study. CAE-based DOE is performed to build prediction math model, CMS process involves DOE to achieve very fast run times while giving results very comparable. Minimized 95th percentile of performance distribution is applied to minimize vehicle sensitivity and road noise levels variation during the optimization process. Finally, the results of optimization were reviewed for performance and robustness.

• 소음진동
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• 제4권4호
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• pp.479-486
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• 1994

The Finite Element Method(FEM) generally used for the structural analysis has some defects, i.e. a great deal of computational time and huge memory capacity of computer are needed in the application to large and/or complex structures, etc. Therefore the Component Mode Synthesis method(CMS), one of sub-structure synthesis methods, was made to improve such demerits and has been developed up to now. In optimum structural modification problems, the sensitivity analysis method is useful, where the sensitivity-calculated by Fox's suggestion-is defined as the diffentials of design variables for the objective values. This paper discusses the vibration minimization techniques for the oper box type structure, in which it is assumed that an engine operates at 10-40Hz range. The results obtained are as follow; (1) The sensitivity of natural frequency could be easily obtained by sensitivity analysis method and the optimum position to insert pillars could be found by using it. (2) The rates of structural modification could be exactly obtained and the natural frequency observed could be easily shifted to the objective value. (3) The maximum amplitude around natural frequency noted could be nearly reduced to 1/25 by modification.