• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.328-334
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• 2001

Up to now. vibration analysis and vibration engineering have been developed, encompassing the aspects of both experimental and analytical techniques. Using experimental modal analysis or modal testing, the mode shapes and frequencies of practical structure can be measured accurately. Curve-Fitting Method is realized through experimental modal identification. In the experimental modal parameter estimation, the estimation of modal damping factor is difficult for complicated and large structure. Also numbers of Selected mode are determined before the procedure. This paper describes the vibration shape of the super-structure model of ship through experimental modal analysis.

• Structural Monitoring and Maintenance
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• 제5권3호
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• pp.345-361
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• 2018

The set of processes performed to determine the dynamic characteristics of the constructed structures is named experimental modal analysis. Using experimental modal analysis and interpreting its results, structural failure can be assessed and then it would be possible to plan for their repair and maintenance. The purpose of the experimental modal analysis is to determine the resonance frequencies, mode shapes and Mode damping for the structure. Diverse methods for determining the shape of the mode by various researchers have been presented. There are pros and cons for each of these methods. This paper presents a method for determining the mode shape of the structures using the response spectrum in the experimental modal analysis. In the first part, the principles of the proposed method are described. Then, to check the accuracy of the results obtained from the proposed method, single and multiple degrees of freedom models were numerically and experimentally investigated.

• 소음진동
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• 제10권6호
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• pp.1009-1016
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• 2000

This paper describes the procedure of increasing the efficiency of experimental modal analysis and updating the quality of FE model using the scaled commercial vehicle frame. In this study, it was found that the experimental modal analysis could be more efficient when the measurements were made on the areas with high kinetic energies. Such areas could be located with the aid of FE modal analysis. Also, the number of measurement points could be decided by considering the dynamic characteristics of full FE model. The correlation of FE model and experimental modal analysis was assessed by the differences between the natural frequencies and MAC matrix, which is based on normal modes. These differences of modal parameters were reduced through the sensitivity and optimization analysis of which objective function consisted of the errors of natural frequencies and the diagonal terms of MAC matrix.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1718-1723
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• 2003

This paper presents a computational method for deformation modes of a flexible body in multibody system from the experimental modal analysis and an efficient method for flexible multibody dynamic analysis by use of the modes. It is difficult to directly use experimental modal parameters in flexible multibody dynamic analysis. The major reasons are that there are many inconsistencies between experimental and analytical modal data and experimental noises are inherent in the experimental data. So two methods, such as, a method for ortho-normalization of experimental modes and the other one for mode expansion, are suggested to gain deformation modes of a flexible body from the experimental modal parameters. Using the virtual work principle, the equation of motion of a flexible body is derived. The effectiveness of the proposed method will be verified in the numerical example of cab vibration of a truck by comparing analysis and test results.

• 한국소음진동공학회논문집
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• 제11권4호
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• pp.43-51
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• 2001

An experimental modal analysis is the process to identify structure's dynamic characteristics such as resonant frequencies, damping values and mode shapes. An experimental model was made of stainless steel in the shape of a circular cylindrical shell and installed on the test bed with jigs. For investigating vibrational characteristics of the continuous circular cylindrical shell with intermediate supports, modal testing is performed by using impact hammer, accelerometer and 8-channel FFT analyzer. The frequency response function(FRF) measurements are also made on the experimental model within the frequency range from 0 to 4kHz. Modal parameters are identified from resonant peaks in the FRF's and animated deformation patterns associated with each of the resonances are shown on a computer screen. The experimental results are compared with analytical and FEA results.

• 한국해양공학회지
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• 제26권1호
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• pp.34-40
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• 2012

This paper presents an experimental modal analysis of a caisson-type breakwater to produce basic information for the structural health assessment of a caisson structure. To achieve the objective, the following approaches are implemented. First, modal analysis methods are selected to examine the modal characteristics of a caisson structure. Second, experimental modal analyses are performed using finite element analyses and lab-scale model tests. Third, damage scenarios that include several damage levels in a foundation-structure interface are designed. Finally, the effects of damage on the modal characteristics are analyzed for the purpose of utilizing them for damage identification.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.233-237
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• 1998

In this work, to identify the dynamic characteristics of disk-spindle system in hard disk drive, experimental modal analysis was performed. And an experimental analysis system including testing apparatus, precision sensors, and analysis software was established in order to perform the testing effectively. From the experimental results, coupled and uncoupled modal characteristics of 3-disk spindle system are clearly identified.

• 한국항해항만학회지
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• 제26권3호
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• pp.281-288
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• 2002

진동해석과 기술에 있어서 실험과 해석분야 모두 다 같이 발전한 것은 사실이지만, 실험해석법은 유한요소법과 같은 이론해석법만큼 발달한 것이라 할 수 없을 것이다. 그 이유 중에 하나로 비선형 방정식을 푸는데 있어 초기치의 선택에 따라 계산시간이 길어지고 해가 종종 발산하기도 하기 때문이다. 일반적으로 실험모드해석에 있어 방정식은 고유진동수와 감쇠비의 비선형 항과 등가강성의 선형 항으로 구성된다. 본 연구에서는 비선형 항을 먼저 구하고, 다음에 선형 항을 구하였다. 개발된 실험모드해석법(곡선맞춤법)을 선체상부구조 모델에 적용하여, 모드 특성치들을 계산하였다. 또한 개발된 프로그램은 그래픽기법을 적용하여 간단한 마우스 조작으로 채용 모드수와 감쇠비를 결정할 수 있도록 하였다.

• 한국강구조학회 논문집
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• 제24권1호
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• pp.119-128
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• 2012

본 연구에서는 실험적 모드해석 기법을 이용하여 외부환경에 직접 노출되어 있는 실제 철도판형교의 full-scale 동적 테스트가 수행되었다. 충격해머 모드실험에 의해 얻어진 철도판형교의 모드 매개변수를 유한요소해석으로부터 구한 고유진동수와 모드형상과 비교, 분석하였다. 실험적 모드해석에 의해 측정된 실험 데이터와 해석적 진동분석에서 얻어지는 출력만의 데이터를 교량 부재의 기하학적 특성 및 재료적 특성을 다양하게 고려하여 모델보정 테크닉에 적용하였다. 철도판형교의 실험적 모드해석 결과를 검증하기 위한 유한요소모델이 모드인식 기법을 이용하여 보정되었다. 실험 데이터와 유한요소해석 기준모델의 모델보정과정의 결과와 함께 부재특성의 변화를 통하여 이루질 수 있는 손상평가에 대한 기초적 데이터베이스가 제공된다.

• 오토저널
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• 제10권2호
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• pp.39-45
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• 1988

The analytical model of an engine mount system with six degrees of freedom is identified using the modal parameters obtained from the experimental modal analysis. The structural parameters, mass moment of inertia of the engine block and stiffness of the rubber mounts, of the engine mount system are determined by using the condition that the estimated model parameters should satisfy the corresponding eigenvalue problem. The simulated modal parameters of the identified analytical model are in good agreement with the measured modal parameters.