• Title/Summary/Keyword: Transient vibration analysis

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Transient Vibration Analysis of an Agricultural Tractor (농업용 트랙터의 과도 진동 분석)

  • 김용준;김경욱
    • Journal of Biosystems Engineering
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    • v.26 no.6
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    • pp.509-516
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    • 2001
  • This paper introduced some advantages of the time-frequency analysis of vibration and investigated, using the time-frequency transform, the characteristics of the transient motion of a tractor seat, which occurred during the tractor traversed over a rectangular obstacle on the flat surface. The characteristics of the short-time courier and wavelet transforms as time-frequency analysis methods were introduced and discussed to figure out which is more suitable to the analysis of the transient motions of agricultural tractors. Using each transform, transient vibration of a tractor seat was analyzed. Results of the analysis showed that the transient vibration of the seat was influenced by the natural frequencies of vertical mode of chassis, pitching mode of engine and pitching mode of cab of the tractor. The time sequence of the natural mode of tractor vibration was also revealed by the time-frequency analysis. The vibration path analysis by the time-frequency transform showed that the vibration energies transmitted from the front mounts to the seat were less than those from the rear mounts. The energy reduction ratios between the cab mounts and seat were also estimated to be about 72∼78%. The front mounts showed larger reduction than the rear mounts. However, the reduction difference between the right and left sides mounts was negligibly small. The short time Fourier transform was found to be a proper method for investigating the transient motions of farm machines and their effects on the ride vibration.

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Transient Vibration Analysis of a Multi-packet Blade System Excited by Nozzle Jet Forces (노즐 분사력에 의해 가진되는 다중 패킷 블레이드계의 과도 진동 해석)

  • Lim, Ha-Seong;Yoo, Hong-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.57-62
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    • 2007
  • A modeling method for the modal and the transient vibration analysis of a multi-packet blade system excited by nozzle jet forces is presented in this paper. Blades are idealized as cantilever beams and the elastic structures like disc and shroud connecting blades are modeled as coupling stiffnesses. A modified Campbell diagram is proposed to identify true resonance frequencies of the multi-packet blade system. Different from the SAFE diagram that employs three dimensional space, the modified Campbell diagram proposed in this study employs a plane to find the true resonance frequencies. To verify the existence of true resonance frequencies, nozzle jet forces are modeled as periodic forces and transient vibration analysis were performed with the modeling method.

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Transient Vibration Analysis of a Multi-packet Blade System Excited by Nozzle Jet Forces (노즐 분사력에 의해 가진되는 다중 패킷 블레이드계의 과도 진동 해석)

  • Lim, Ha-Seong;Yoo, Hong-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.7
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    • pp.711-717
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    • 2008
  • A modeling method for the modal and the transient vibration analysis of a multi-packet blade system excited by nozzle jet forces is presented in this paper. Blades are idealized as cantilever beams and the elastic structures like disc and shroud connecting blades are modeled as coupling stiffnesses. A modified Campbell diagram is proposed to identify true resonance frequencies of the multi-packet blade system. Different from the SAFE diagram that employs three dimensional space, the modified Campbell diagram Proposed in this study employs a plane to find the true resonance frequencies. To verify the existence of true resonance frequencies, nozzle jet forces are modeled as periodic forces and transient vibration analysis were performed with the modeling method.

Transient Response Characteristics of Vehicle Seatbelt (자동차 시트벨트의 과도응답 특성에 관한 연구)

  • Kim, Chang-Hee;Lee, Seok-Soon
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.9
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    • pp.71-77
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    • 2020
  • In recent years, as a consequence of the technological advancements in the automobile industry and changes in consumer demands, the reduction of noise inside vehicles rather than vehicle performance has increasingly become an important factor of interest. To date, most studies have focused on noise and vibration reduction techniques for the engine and drive system of vehicles. In this research, a comparative analysis for reducing the effect of vehicle seatbelts on the transient response is performed using the test of vehicle conditions and transient response analysis in accordance with seatbelt conditions. After the sensitivity analysis, the specifications for improvement were designed based on the transient response analysis. It was confirmed that the transient response characteristics were improved by the transient response analysis and vehicle conditions test. Through computer-aided engineering, the transient response characteristics of seatbelts were checked with less cost and time.

A State-Space Transient Response Analysis of Rotor-Bearing System with Base Excitation (기초가진 로터-베어링 시스템의 상태공간 과도응답해석)

  • 이안성;김병옥;김영철;김영춘
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.669-674
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    • 2004
  • In this study, the analytical method to evaluate the response of rotor-bearing system subjected to base excitation was presented. The equations of motion contain speed dependent gyroscopic terms, base rotation dependent parametric terms and several forcing function terms which depend on linear accelerations, rotational accelerations and a combination of linear and rotational combination. The study of rotor-bearing system excited by its base motion is not only able to predict the rotational performance, but provides the fundamental data for vibration isolation. In order to illustrate transient response, transient response analysis of a practical application sample were performed. The transient response was carried out for the given base excitation by using the state-space Newmark method that incorporates the average velocity concept.

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A study on response analysis of 6-DOF pneumatic vibration isolation table loaded by transient movements of carriage on it (상판 위 질량의 순간적인 움직임에 의해 가진되는 6-자유도 공압제진대의 진동 응답에 대한 연구)

  • Sun, Jong-Oh;Shin, Yun-Ho;Kim, Kwang-Joon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.97-102
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    • 2007
  • As environmental vibration requirements on precision equipments get more stringent, use of pneumatic vibration isolators becomes more crucial and, hence, their dynamic performance needs to be further improved. Dynamic behavior of those pneumatic vibration isolation tables is very important to both manufacturer and customer as performance specifications. Together with conventional transmissibility, transient response characteristics are another critical performance index especially when movements of components, e.g., x-y tables, of the precision equipments are very dynamic. In this paper, analysis on transient response of a pneumatic vibration isolation table loaded by a mass moving on it is presented. This is a conventional dynamics problem on a rigid body with 6 degree of freedom and a mass with another degree of freedom. How to obtain transient responses of the isolation table is described when the movements of the mass are prescribed relative to the table.

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A Study on Response Analysis of 6-DOF Pneumatic Vibration Isolation Table Loaded by Transient Movements of Carriage on It (상판 위 질량의 순간적인 움직임에 의해 가진되는 6-자유도 공압제진대의 진동 응답에 대한 연구)

  • Sun, Jong-Oh;Shin, Yun-Ho;Kim, Kwang-Joon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.6 s.123
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    • pp.515-523
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    • 2007
  • As environmental vibration requirements on precision equipments get more stringent, use of pneumatic vibration isolators becomes more crucial and, hence, their dynamic performance needs to be further improved. Dynamic behavior of those pneumatic vibration Isolation tables is very important to both manufacturer and customer as performance specifications. Together with conventional transmissibility, transient response characteristics are another critical performance index especially when movements of components, e.g., x-y tables, of the precision equipments are very dynamic. In this paper, analysis on transient response of a pneumatic vibration isolation table loaded by a mass moving on it is presented. This is a conventional dynamics problem on a rigid body with 6 degree of freedom and a mass with another degree of freedom. How to obtain transient responses of the isolation table is described when the movements of the mass are prescribed relative to the table.

Transient Power Flow Analysis of Beam and Plate (과도 입력파워에 대한 보와 평판의 파워흐름해석)

  • Hwang, Dae-Woong;Seo, Seong-Hoon;Kwon, Hyun-Wung;Hong, Suk-Yoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.7 s.124
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    • pp.624-631
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    • 2007
  • PFA (power flow analysis) has been recognized as a useful method in vibration analysis of medium-to-high frequency ranges. Until now, PFA method has been developed for steady-state vibration problems. In this paper, PFA method has been expanded to transient problem. New energy governing equations are derived considering time dependent terms in beam and plate. Analytic solutions of those equations are found in simple beam and plate, and are verified by comparing with modal solutions.

An Analysis on the Vibration Characteristic of a Automobile at the Sudden Change of an Accelerator under Traveling (주행중 가속페달의 급조작시 승용차의 진동특성 해석)

  • 홍동표;정태진;김상수;태신호
    • Journal of KSNVE
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    • v.4 no.3
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    • pp.353-363
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    • 1994
  • The non-preiodic fluctuation of the engine torque appears to be the major source of the torsional vibration of the automotive driveline. The reduction of this torsional vibration hs become a significant problem along with the requirements of higher performance. The shuffle(tip-in, tip-out) is the transient vibration phenomenon of a vehicle which appears at the sudden change of an accelerator under traveling. By executing of an experiment and a simulation using a model, it has become possible to obtain the design parameter of a driveline for the torsional vibration. This paper presents an experimental and theoretical research on the transient vibration phenomenon of a vehicle which appears at the sudden change of an accelerator under traveling. A dynamic model for the automotive driveline was developed, and all parameters of the mmdel were evaluated with experimental data. The results are as follows: (1) The lower the gea ratio of the transmission is, the more the transient vibration phenomenon of a vehicle appears clearly. (2) The transient vibration phenomenon of a vehicle is affected by the design parmeter of the driveline.

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A study on the Transient Torsional Vibrations of Four Stroke Marine Diesel Engines (선박용 4행정 디젤엔진의 과도 비틀림 진동에 관할 연구)

  • Lee, D.C.;Yu, J.D.;Jeon, H.J.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.44-50
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    • 2002
  • Theoretical analysis on the transient torsional vibration was started from early 1960's for high power synchronous motor application. As for marine engineering, simulation and measuring techniques of transient torsional vibration have been steadily studied by manufacturer of flexible coupling and designer of four stroke marine diesel engine. In this paper, the simulation method of transient torsional vibration for four stroke marine diesel engine application using Newmark method is introduced.

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