• Title/Summary/Keyword: 모달 해석

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Analysis of Durability of Torsion Beam Axle Using Modal Stress Recovery Method (모달 응력 회복법(Modal Stress Recovery)을 이용한 Torsion Beam Axle 내구해석)

  • Ko, Jun-Bok;Lim, Young-Hoon;Lee, Dong-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.10
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    • pp.1339-1344
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    • 2010
  • MSM (Modal Superposition Method) is a technique for analyzing structural durability by taking the vibration characteristics into consideration. In this paper, MSR (Modal Stress Recovery) method, which is similar to MSM, was reviewed to check its validity as a durability analysis method. The MSR method directly calculates the modal displacement time history in multibody dynamics analysis; as a result, the total analysis time is shorter than that of MSM method. We conduct durability analysis using the MSR method and a durability test of a torsion beam axle that is affected by various road loads within the natural frequency of the beam axle. The analysis results for critical location and durability were in good agreement with the respective test results. Therefore, durability analysis using the MSR method is effective in predicting the durability of the structures of various dynamic systems.

Constructing Equations of Motion for a Dynamic System from Modal Parameters (모달 파라미터를 이용한 동적 시스템의 운동 방정식 구성)

  • Hwang, Woo-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.1
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    • pp.40-45
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    • 2007
  • Modal analysis or modal test is a routine process to get the modal parameters of a dynamic system. The modal parameters include the natural frequencies, damping ratios and mode shapes. This paper presents a method that can derive the equations of motion for a dynamic system from the modal parameters obtained by the modal analysis or modal test. The present method based on the relation between the eigenvalues and eigenvectors of the state space equation derives the mass, damping and stiffness matrices of the system. The numerical verifications for the simple mass-spring-damper system and the cantilevered beam prove the efficiency and accuracy of the present method.

Study on Modal Test Method for Vibration Characteristics of the Cylindrical Structure Filled with Liquid (액체가 채워진 원통형 구조물의 진동 특성 규명을 위한 모달 시험 방법 연구)

  • Kim, Gen-Sang;Kim, Mun-Guk;Kim, In-Gul;Park, Jae-Sang;Park, Soon-Hong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.8
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    • pp.621-630
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    • 2018
  • In the case of launch vehicles using liquid fuel, natural frequency changes due to fuel consumption after launch, and a modal test is essential to investigate its effect. However, when relying on modal test to characterize the free vibration characteristics, the testing time is excessively increased and accuracy is reduced. Therefore, this paper suggests a modal test method with finite element analysis to overcome these drawbacks. A cylindrical structure filled with liquid are considered as a study model, and modal tests and finite element analyses are performed. The modal tests are conducted by an impulsive method using an impact hammer and accelerometers. Through the comparison of the modal test and the finite element analysis results, the validity of the proposed modal test method is verified. In addition, the free vibration characteristics and the tendency for the cylindrical structure according to the liquid filled ratio were investigated.

Design of dataglove based multimodal interface for 3D object manipulation in virtual environment (3 차원 오브젝트 직접조작을 위한 데이터 글러브 기반의 멀티모달 인터페이스 설계)

  • Lim, Mi-Jung;Park, Peom
    • 한국HCI학회:학술대회논문집
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    • 2006.02a
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    • pp.1011-1018
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    • 2006
  • 멀티모달 인터페이스는 인간의 제스처, 시선, 손의 움직임, 행동의 패턴, 음성, 물리적인 위치 등 인간의 자연스러운 행동들에 대한 정보를 해석하고 부호화하는 인지기반 기술이다. 본 논문에서는 제스처와 음성, 터치를 이용한 3D 오브젝트 기반의 멀티모달 인터페이스를 설계, 구현한다. 서비스 도메인은 스마트 홈이며 사용자는 3D 오브젝트 직접조작을 통해 원격으로 가정의 오브젝트들을 모니터링하고 제어할 수 있다. 멀티모달 인터랙션 입출력 과정에서는 여러 개의 모달리티를 병렬적으로 인지하고 처리해야 하기 때문에 입출력 과정에서 각 모달리티의 조합과 부호화 방법, 입출력 형식 등이 문제시된다. 본 연구에서는 모달리티들의 특징과 인간의 인지구조 분석을 바탕으로 제스처, 음성, 터치 모달리티 간의 입력조합방식을 제시하고 멀티모달을 이용한 효율적인 3D Object 인터랙션 프로토타입을 설계한다.

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A Study on the Optimization of a Spacecraft Structure by Using Coupled Load Analysis Model and Modal Transient Analysis (연성하중해석 모델과 모달과도해석을 이용한 위성체 구조부재의 최적화 연구)

  • Hwang, Do-Soon;Lee, Young-Shin;Kim, In-Gul
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.6
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    • pp.34-48
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    • 2004
  • In this paper an optimization algorithm is suggested to reduce the huge computation time in the optimum design of large structures, especially in spacecraft structures. It combines the coupled load analysis model using a constrained mode of component mode synthesis and the modal transient analysis. The computer simulation code is developed and evaluated in optimizing spacecraft platforms. The developed algorithm can alleviate the computational load with adequate accuracy. From the optimization of a spacecraft structural member, the characteristics of each structural member can be understood.

Akaike Information Criterion-Based Reliability Analysis for Discrete Bimodal Information (바이모달 이산정보에 대한 아카이케정보척도 기반 신뢰성해석)

  • Lim, Woochul;Lee, Tae Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.12
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    • pp.1605-1612
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    • 2012
  • The distribution of a response usually depends on the distribution of the variables. When a variable shows a distribution with two different modes, the response also shows a distribution with two different modes. In this case, recently developed methods for reliability analysis assume that the distribution functions are continuous with a mode. In actual problems, however, because information is often provided in a discrete form with two or more modes, it is important to estimate the distributions for such information. In this study, we employ the finite mixture model to estimate the response distribution with two different modes, and we select the best candidate distribution through AIC. Mathematical examples are illustrated to verify the proposed method.

Development of a Variable Dynamic Force Type Exciter for Modal Test of a Large Structure (대형구조물 동특성 실험을 위한 가변 동하중 가진시스템 개발)

  • 손성완;이홍기;최수현;강동억
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.381.2-381
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    • 2002
  • 많은 동적해석 설계자들이 재료물성치의 불확실성, 연결강성 그리고 경계조건등의 해석상에서 나타날 수 있는 불확실성 때문에 모달 테스트에 많은 관심을 가지고 있었으며 또한 수행해 왔다. 그러나 대형구조물의 경우 저주파수 대역에서의 가진력 크기, 가진력 계측 문제등으로 동특성 실험을 위한 모달 테스트를 수행하기가 쉽지 않은 실정이다. (중략)

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Estimation of Modal Parameters for Plastic Film-Covered Greenhouse Arches (비닐하우스 아치구조의 모달계수 산정)

  • Cho, Soon-Ho
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.2
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    • pp.67-74
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    • 2010
  • To a series of vibration records obtained from experimental modal testing using a fixed hammer and roving accelerometers for greenhouse arch structures, modal parameters such as natural frequencies, damping ratios and mode shapes are extracted by applying the two most advanced system identification methods in the frequency-domain up to now, so-called PolyMAX and FDD. The former involves both input and output data, while the latter utilizes only the output data. The possibility of determining the static buckling load, detecting damages, etc., for very slender steel-pipe arches by means of a non-destructive testing method based on vibration measurements is primarily investigated. The extracted modal parameters generally correlated well with those obtained using finite element analysis, demonstrating promising results for further on-going research.

Damage Detection of a Steel Member Using Modal Testing (강부재의 손상발견을 위한 모달실험 기법)

  • Jang, Jeong Hwan;Lee, Jung Whee;Kim, Sung Kon;Chang, Sung Pil
    • Journal of Korean Society of Steel Construction
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    • v.9 no.4 s.33
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    • pp.467-477
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    • 1997
  • A series of experimental tests have been performed on a tube beam in which artificial damage is applied in order to address damage detectability using modal analysis. Modal parameters considered are frequency, displacement mode shape and strain mode shape CoMAC(Coordinate Modal Assurance Criterion) and Modal Vector Error have been adopted for presenting the change of displacement mode shape and strain mode shape. It is revealed strain mode shape is the most sensitive to damage.

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Model Updating of Head Stack Assembly using Modal Tuning (모달 튜닝을 이용한 하드디스크 구동기의 모델 개선)

  • Lee, Jin-Koo;Kim, Dong-Woohn;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.243-248
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    • 2000
  • 하드디스크의 트랙 밀도를 높이기 위해서는 충분한 서보대역을 갖는 액츄에이터를 개발하는 것이 필수적이다 이 논문에서는 액츄에이터의 동특성 중에서 서보대역을 제한하는 주된 요인을 알아보기 위해 실험 모드 해석과 유한 요소 해석을 수행하였다. 우선 액츄에이터를 구성하고 있는 VCM 코일, E 블럭, 서스펜션등의 부분계에 대한 유한 요소 해석을 수행하였고 모달 실험을 통해 이를 검증하였다. 검증된 각 부분계의 모델을 결합하여 한 개의 서스펜션을 갖는 액츄에이터 시스템의 유한 요소 모델을 개발하였고 이를 통해 서보 성능과 관계된 모달 파라미터들을 규명하였다.

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