• Title/Summary/Keyword: Vibration condition

Search Result 2,069, Processing Time 0.025 seconds

A Study on Improvement of Aiming Ability using Disturbance Measurement in the Ground Military Vehicle (지상무기체계에서의 외란측정을 이용한 정밀 지향성 향상 연구)

  • Yoo, Jin-Ho;Park, Byung-Hun
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.10 no.2
    • /
    • pp.12-20
    • /
    • 2007
  • The aiming ability is a key to improve the accuracy performance of the gun pointing system in the ground military vehicle. This paper describes the new detection method of chatter vibration using disturbance acceleration in the pointing structure. In order to analysis the vibration trends of the pointing system occurred while the vehicle driving, acceleration data obtained from vehicle was processed by using data processing algorithm with moving average and Hilbert transform. The specific mode constants of acceleration were obtained from various disturbances. Vehicle velocity, road condition and property of pointing structure were considered as factors which make the change of vibration trend in vehicle dynamics. Finally, back propagation neural networks have been applied to the pattern recognition of the classification of vibration signal in various driving conditions. Results of signal processing were compared with other condition result and analysed.

Free Vibration Characteristics of 5 × 5 Spacer Grid Assembly Supporting the PWR Fuel Rod (경수로 연료봉을 지지하는 5×5 지지격자체의 자유진동특성)

  • 강흥석;윤경호;송기남;최명환
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.14 no.6
    • /
    • pp.512-519
    • /
    • 2004
  • This paper described the free vibration characteristics of Optimized H Type (OHT) spacer grids (SG) supporting the PWR fuel rod. The vibration test and the finite element (FE) analysis are performed under the free boundary condition and the clamped at two points (or three points) in the bottom which is the same one as the experimental condition for the dummy rod continuously supported by spacer grids. A modal test is conducted by the impulse excitation method using an impulse hammer and an accelerometer, and the TDAS module of the I-DEAS software is used to acquire and analyze the sensor signals. The softwares related to the FE analysis are the I-DEAS for the geometrical shape modeling and meshing, and the ABAQUS for solving. The fundamental frequency of the OHT SG by experiment under a clamped condition at two points is 175.18 Hz, and shows a bending mode. We think there is no resonance between the fuel rod and the SG because the SG's frequency is higher than that of the fuel rod existing in the range from 30 to 120 Hz. The fundamental frequency of the SG under the free boundary condition is 349.2 Hz showing a bending mode, and the results between the test and the analysis have a good agreement with maximum 7 % in error It is also found that the FE analysis model of the OHT SGs to analyze an impact, a buckling and vibration et al. has been generated with reliability.

Vibration Characteristics of A Rectangular Tank in accordance with Changing Thickness And Boundary Condition (경계조건과 두께 변화에 따른 사각탱크의 진동 특성)

  • Bae, S.Y.
    • Journal of Power System Engineering
    • /
    • v.15 no.1
    • /
    • pp.24-31
    • /
    • 2011
  • Rectangular box type structures are used in many fields of civil, mechanical and marine engineering. Especially, Most ship structures are often in contact with inner or outer fluid, like ballast, fuel and stem tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine and propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tanks. Many authors have studied vibration of rectangular tanks containing fluid. Few research on dynamic interaction among tank walls filled with fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass of water have to be considered. In the previous report, a numerical analysis is performed for the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region, and mode characteristics in accordance with changing breadth of the plates by using finite element method for plates and boundary element method for fluid region. In this paper, the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region, and mode characteristics in accordance with changing length, thickness, and boundary condition of the plates are investigated numerically and discussed.

Vibration Mode Characteristics on a Propeller in very Large Vessel (대형선박의 추진기 진동 모우드 특성)

  • Kim J.H.;Cho D.S.;Han S.Y.
    • Special Issue of the Society of Naval Architects of Korea
    • /
    • 2005.06a
    • /
    • pp.97-106
    • /
    • 2005
  • According to the trends of construction of large size vessel with high power the natural frequencies of the bending modes of propeller blades have been lower than the past. Therefore, it is expected that the noise and vibration problems of the marine propeller are frequently occurred. As main issue of the propeller noise and vibration problem, the cavitation noise and singing noise due to the flow induced excitation of the bending modes of propeller blade in the high frequency range has been studied by the hydrodynamic researchers in the view point of the excitation force reduction. In this paper, the vibration mode characteristics of propeller with a large diameter in very large vessel are investigated by the vibration analysis of the finite element method using MSC/Nastran and the vibration measurement by the impact test on the propeller blade. According to the results, the natural frequencies of various blade bending modes in water entrained condition could be estimated from the natural frequencies taken by the measurement and free vibration analysis in the dry condition, and it could be estimated how the high frequency noise such as singing is generated from the blade bending modes.

  • PDF

Development of an Integrated Management System for Maintenance Parameters and Rotary Machine of Hydro-power Plant (수력발전소 정비변수 및 회전체 통합관리 시스템 개발)

  • Shin, Sung-Hwan;Park, Jin-Ho;Yoon, Doo-Byung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2012.04a
    • /
    • pp.263-269
    • /
    • 2012
  • Condition-based maintenance (CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance system as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon Hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

  • PDF

Condition Monitoring for Coil Break Using Features of Stationary Rolling Region (정상 압연 구간의 특징을 이용한 판 파단의 상태감시)

  • Oh, J.S.;Yang, S.W.;Shim, M.C.;Caesarendra, W.;Yang, B.S.;Lee, W.H.
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.19 no.12
    • /
    • pp.1252-1259
    • /
    • 2009
  • Due to the international competition and global pressure, the roll speed is increased. However, higher speeds increase the power density in the process as well as the plant's potential to react with vibrations. Under certain operating conditions, vibrations may occur, which again cause chattermarks, strip rupture or coil break fault. The appropriate condition monitoring is needed to improve product quality and availability. The aim of condition monitoring is to reduce maintenance costs, increase productivity and improve product quality. This paper proposes a condition monitoring tool designed for the classification of coil break fault. This method is used to cold rolling mill for faults monitoring based on vibration and motor current signals. The results show that the performance of classification has high accuracy based on experimental work.

Development of an Integrated Management System for Maintenance Parameters and Rotary Machine of Hydro-power Plant (수력발전소 정비변수 및 회전체 통합관리시스템 개발)

  • Shin, Sung-Hwan;Park, Jin-Ho;Yoon, Doo-Byung;Son, Ki-Sung
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.22 no.6
    • /
    • pp.574-581
    • /
    • 2012
  • Condition-based maintenance(CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance strategy as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

Development of Vibration Diagnosis System for Rotating Machine (회전기계의 이상진동진단 시스템의 개발)

  • 양보석;장우교;김호종
    • Journal of KSNVE
    • /
    • v.6 no.3
    • /
    • pp.325-332
    • /
    • 1996
  • One of the greatest shortcoming in today's predictive maintenance program is the ability to diagnose the mechanical and electrical problems within the machine when the vibration exceeds preset overall and spectral alarm levels. In this study, auto-diagnosis system is constructed by using A/D converter to convert analog to digital singal. With this device the system analyses input signal to diagonosis machine condition. Many plots, which display machine condition, and input values of every channel are calculated in this system. If the falut is found, the system diagnoses automatically using fuzzy algorithm and trend monitoring. Prediction is also performed by the grey system theory. Operator finds out eh machine operating condition intuitively based on with personal computer CRT in using this system.

  • PDF