• Title/Summary/Keyword: CMS(component mode synthesis method)

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Development of Acoustic Substructure Synthesis Method using Component Mode Synthesis Method (모드합성법을 이용한 음향부분구조합성법의 개발)

  • 고상철;조용구;오재응;김준태;김진오
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.10a
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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.

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Analysis of a Flexible Multi-body System with Over-constraints (여유구속을 갖는 유연체 기계시스템의 동역학 해석)

  • Seo, Jong-Hwi;Park, Tae-Won;Chae, Jang-Soo;Seo, Hyun-Seok
    • Proceedings of the KSME Conference
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    • 2003.04a
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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.

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Structural Dynamics Modification for a Large Structure using Component Mode Synthesis Methods (구조합성법을 이용한 큰 구조물에서의 구조동특성변경법)

  • Lee, Moon-Seok;Park, Youn-Sik;Park, Young-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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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.

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Dynamic Modeling of Bolt Joints Using Lumped Mass-Spring Model (집중 질량-스프링 모델을 이용한 볼트 결합부 모델링)

  • Go, Gang-Ho;Lee, Jang-Mu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.3
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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.

Analysis of Vibration Characteristics of a Full Vehicle Model Using Substructure Synthesis Method (부분구조합성법을 이용한 전차량 모델의 진동 특성 분석)

  • Kim, Bum-Suk;Kim, Bong-Soo;Yoo, Hong-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.5
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    • pp.519-525
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    • 2010
  • The finite element (FE) method is generally used to model and simulate the physical behavior of large structures, such as passenger vehicles or aircraft. However, FE analysis involves a very large computation time and cost for developing the analysis model. Therefore, the vibration characteristics of large structural systems are often analyzed using the component mode synthesis (CMS) method, which is one of the substructure synthesis methods. In this study, the vibration characteristics of passenger vehicles are analyzed by using the substructure synthesis method. A passenger vehicle model, which includes a vehicle body, suspension systems, and a sub-frame, is presented. The physical components of the vehicle system are modeled as equivalent substructures using the Craig-Bampton method of CMS. The vibration characteristics, such as the natural frequencies and mode shapes and frequency response, of the vehicle system are determined. The effects of variations in some design parameters on the vibration characteristics of the full vehicle model are also investigated.

Structural Dynamics Modification using Reduced Model for Having Non-matching Nodes (불일치 절점을 가지는 경우의 축약된 모델을 이용한 동특성 변경법)

  • Kang, Ok-Hyun;Park, Youn-Sik;Park, Young-Jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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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.

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CAE-based DFSS Study for Road Noise Reduction (Road Noise 개선을 위한 CAE 기반 DFSS Study)

  • Kwon, Woo-Sung;Yoo, Bong-Jun;Kim, Byoung-Hoon;Kim, In-Dong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.04a
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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.

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CAE-based DFSS Study for Road Noise Reduction (로드 노이즈 개선을 위한 전산응용해석 기반 DFSS 연구)

  • Kwon, Woo-Sung;Yoo, Bong-Jun;Kim, Byoung-Hoon;Kim, In-Dong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.7
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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.

A Study on the Vibration Minimization Techniques for the Open Box Type Structure (열린 상자형 구조물의 진동 최소화 기법에 관한 연구)

  • 박석주;오재응;이장용;박성현
    • Journal of KSNVE
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    • v.4 no.4
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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.

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