• Title/Summary/Keyword: modal energy

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Introduction of energy isoclines for the vibration fatigue problem (진동내구 평가를 위한 Energy Isoclines 선정 방법)

  • Bae, Chul-Yong;Kim, Chan-Jung;Lee, Dong-Won;Lee, Bong-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.789-794
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    • 2008
  • The damage identification in a flexible system requires modal informations which is represented by FRF(Frequency response function) or modal parameters. In this paper, energy isoclines are introduced to access the prediction of fatigue damage on a flexible component exposed mainly to the exciting source rather than external forces. After deriving the concerned function, energy isoclines, from the investigation of the relationship between energy and damage, its practical application is explained by the simple uni-axial excitation test for the notched round bar.

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Fault detections in ring structures using vibration modes (진동모드를 이용한 링 구조물의 결함 탐지)

  • Kim, Seock-Hyun;Jang, Ho-Sik
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1925-1932
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    • 2000
  • Damage detection methods using vibration modes are investigated on ring structures and. modal behavior of the slightly asymmetric rings is examined. Mode shapes changes, MSER(modal strain energy ratio) and MCR(modal curvature ratio) are applied to identify the locations of faults or damages. Parameters are calculated and compared by finite element analysis on rings with designed local damages. Damages are modeled as reduced stiffness in the analysis. The results show MSER and MCR can be proper factors to detect local damages in ring structures.

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Surface Wave Analysis in Modal and Ray solutions (Mode와 Ray 해법에서의 표면파에 관한 해석)

  • 명노훈
    • Proceedings of the Optical Society of Korea Conference
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    • 1989.02a
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    • pp.161-164
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    • 1989
  • When an electric (or a magnetic) line source is located near the surface, surface wave type field is generated and the energy associated with this field is guided very close to the impedance surface. In this paper, field strength is calculated by the exact modal and ray methods for a line source excited parallel plate waveguide. The surface wave contribution to the modal and ray solutions is anticipated very strong and must be included in both solutions.

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Modal Analysis Employing In-plane Strain of Cantilever Plates Undergoing Translational Acceleration (병진 가속을 받는 외팔 평판의 면내 변형율을 이용한 진동 해석)

  • Lim, Hong-Seok;Yoo, Hong-Hee
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.667-672
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    • 2004
  • A modeling method for the modal analysis of cantilever plates undergoing in-plane translational acceleration is presented in this paper. Cartesian deformation variables are employed to derive the equations of motion and the resulting equations are transformed into dimensionless forms. To obtain the modal equation from the equations of motion, the in-plane equilibrium strain measures are substituted into the strain energy expression based on Von Karman strain measures. The effects of two dimensionless parameters (related to acceleration and aspect ratio) on the modal characteristics of accelerated plates are investigated through numerical studies.

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Modal Analysis Employing In-plane Strain of Cantilever Plates Undergoing Translational Acceleration (병진 가속을 받는 외팔 평판의 면내 변형률을 이용한 진동 해석)

  • Yoo Hong Hee;Lim Hong Seok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.6 s.237
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    • pp.889-894
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    • 2005
  • A modeling method for the modal analysis of cantilever plates undergoing in-plane translational acceleration is presented in this paper. Cartesian deformation variables are employed to derive the equations of motion and the resulting equations are transformed into dimensionless forms. To obtain the modal equation from the equations of motion, the in-plane equilibrium strain measures are substituted into the strain energy expression based on Von Karman strain measures. The effects of two dimensionless parameters (related to acceleration and aspect ratio) on the modal characteristics of accelerated plates are investigated through numerical studies.

Periodic seismic performance evaluation of highway bridges using structural health monitoring system

  • Yi, Jin-Hak;Kim, Dookie;Feng, Maria Q.
    • Structural Engineering and Mechanics
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    • v.31 no.5
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    • pp.527-544
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    • 2009
  • In this study, the periodic seismic performance evaluation scheme is proposed using a structural health monitoring system in terms of seismic fragility. An instrumented highway bridge is used to demonstrate the evaluation procedure involving (1) measuring ambient vibration of a bridge under general vehicle loadings, (2) identifying modal parameters from the measured acceleration data by applying output-only modal identification method, (3) updating a preliminary finite element model (obtained from structural design drawings) with the identified modal parameters using real-coded genetic algorithm, (4) analyzing nonlinear response time histories of the structure under earthquake excitations, and finally (5) developing fragility curves represented by a log-normal distribution function using maximum likelihood estimation. It is found that the seismic fragility of a highway bridge can be updated using extracted modal parameters and can also be monitored further by utilizing the instrumented structural health monitoring system.

Relationships between Urban Transportation System and Energy Efficiency (도시교통체계와 에너지효율성의 관계분석)

  • Sin, Yong-Eun;Gang, Min-U;Im, Mi
    • Journal of Korean Society of Transportation
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    • v.28 no.2
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    • pp.161-169
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    • 2010
  • The amount of energy consumed by a transportation system in a city is influenced not just by a transportation system itself but also by city's spatial character. Yet there have been very limited studies on this subject. This study investigates the factors that influence the energy consumption by a transportation system and city's spatial character. The model of an urban area confined within a definite boundary is assumed in order to develop the relationships between the energy consumption and the transportation system. Various assumptions on the character of a city and activities are made. An equation for computation of the energy consumption is derived with such factors as modal split, densities of residents and workers, as well as technological development. Using the equation, sensitivity analyses are performed in order to identify the relationships between energy consumption and influencing factors. It is found that the modal split is the most powerful factor that determines the energy consumption by the transportation system. Yet it is also found that the densities of residents and workers and the technological factors are very important in determining the amount of energy consumption as well.

Performance Evaluation of Gas Cleaning Industrial Filters using a Bi-Modal Test Aerosol for Dust Loading Studies

  • Lee, Jae-Keun;Kim, Seong-Chan;Benjamin Y.H. Liu
    • Journal of Energy Engineering
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    • v.5 no.2
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    • pp.131-137
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    • 1996
  • Typical size distribution of emission particulates is bi-modal in shape with particles in the fine mode (< 2.0 $\mu\textrm{m}$) and the coarse mode. An experimental study of pressure drop across the industrial gas cleaning filters has been conducted using particle mixture of fine alumina and coarse Arizona dusts with a rotating aerosol disperser to generate the bi-modal test aerosol. Pressure drop increased linearly with increasing mass loading. The pressure drop was found to be strongly dependent upon the mass ratio of fine to coarse particles. The smaller the mass ratio of fine to coarse particles and the higher face velocity are, the faster pressure drop rises. The fine particles and the greater inertia of the particle moving fast would cause a denser cake formation on the filter surface, resulting in a greater specific resistance to the gas flow.

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Bearing Modeling of Superconducting Magnetic Bearings-Flywheel System (초전도 자기베어링-플라이휠 시스템의 베어링 모델링)

  • 김정근;이수훈
    • Journal of KSNVE
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    • v.9 no.5
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    • pp.891-898
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    • 1999
  • The purpose of Superconducting Magnetic Bearing Flywheel Energy Storage System (SMB-FESS) is to store unused nighttime electricity until it is needed during daytime. An analytical model of the SMB-FESS is necessary to identify the system behavior. At first, we have to model the superconducting magnetic bearing. Modeling the SMB is same as estimating the bearing parameter. The theoretical modal parameter is calculated through the equation of motion and the experimental modal parameter is estimated through the impact testing (modal testing). The bearing parameter is searched by using the non-linear least square method until the theoretical result corresponds to the experimental result. The suggested modeling method is verified by comparing experimental and analytical frequency response function.

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Prediction about Potential Reduction of CO2 through Modal Shift of Car Travelers to Train (여객부문 도로-철도 Modal shift에 따른 CO2 발생량 예측 연구)

  • Kim, Cho-Young;Lee, Cheul-Kyu;Kim, Yong-Ki;Phirada, Pruitichaiwiboon
    • Proceedings of the KSR Conference
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    • 2010.06a
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    • pp.2292-2296
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    • 2010
  • 2020 Korea GHG reduction goal is decreasing 4% compared with that of 2005. Effective counterplan of GHG redection goal needs to set for inductrial allocation and various reduction GHG technologies and policies for transportation have been developed. Modal shifr is one of these main policy and it focused on shifting as much freight as economically meaningful under current market conditions. It improves energy efficiency, consequently reduces GHG effect. This study is proposed as a preliminary studay of analyzing Modal shift effect. modal shift of car travelers to train is concerned in Seoul-Busan section, This study is based on a scenario which can maximize passenger occupancy rate to get the GHG reduction effect and the effect of modal shift of car to train is identified. According to this result, we can get GHG reduction effect through dealing with maximizing passenger occupancy rate on train. Therefore, in order to enhance this modal shift effect, train using rate need to increased and also improvement of policies and cost system are need to be considered to promote increasing use of train.

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