• Title/Summary/Keyword: Torsional vibration stress

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Torsional Stress Prediction of Turbine Rotor Train Using Stress Model (스트레스 모델을 이용한 터빈 축계의 비틀림 응력 예측)

  • Lee, Hyuk-Soon;Yoo, Seong-Yeon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.9
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    • pp.850-856
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    • 2013
  • Torsional interaction between electrical network phenomena and turbine-generator shaft cause torsional stress on turbine-generator shaft and torsional fatigue fracture on vulnerable component, but the prediction of the torsional stress is difficult because the torsional stress is occurred instantly and randomly. Therefore continuous monitoring of the torsional stress on turbine-generator shaft is necessary to predict the torsional fatigue, but installing the sensors on the surface of the shaft directly to monitor the stress is impossible practically. In this study torsional vibration was measured using magnetic sensor at a point of turbine-generator rotor kit, the torsional stress of whole train of rotor kit was calculated using rotor kit's stress model and the calculated results were verified in comparison with the measured results using strain gauge at several point of turbine-generator rotor kit. It is expected that these experiment results will be used effectively to calculate the torsional stress of whole train of turbine-generator rotor in power plants.

Torsional stress prediction of turbine rotor train using stress model (스트레스 모델을 이용한 터빈 축계의 비틀림 응력 예측)

  • Lee, Hyuk-Soon;Yoo, Seong-Yeon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.862-867
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    • 2013
  • Torsional interaction between electrical network phenomena and turbine-generator shaft cause torsional stress on turbine-generator shaft and torsional fatigue fracture on vulnerable component, but the prediction of the torsional stress is difficult because the torsional stress is occurred instantly and randomly. Therefore continuous monitoring of the torsional stress on turbine-generator shaft is necessary to predict the torsional fatigue, but installing the sensors on the surface of the shaft directly to monitor the stress is impossible practically. In this study torsional vibration was measured using magnetic sensor at a point of turbine-generator rotor kit, the torsional stress of whole train of rotor kit was calculated using rotor kit's stress model and the calculated results were verified in comparison with the measured results using strain gauge at several point of turbine-generator rotor kit. It is expected that these experiment results will be used effectively to calculate the torsional stress of whole train of turbine-generator rotor in power plants.

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Torsional Vibration Stress Analysis for Shafting in Reciprocating Machine by Transfer Stiffness Coefficient Method (전달강성계수법에 의한 왕복 기계 축계의 비틀림진동 응력해석)

  • 최명수
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.8
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    • pp.749-756
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    • 2004
  • While designing shafting in reciprocating machines with internal combustion engines which derive generators, pumps, and vehicles, it is very important to calculate the additional stress of shafting by torsional vibration. In this paper, the transfer stiffness coefficient method which is based on the successive transfer of stiffness coefficient was applied to the calculation of the additional stress of shafting in reciprocating machine by torsional vibration. In order to confirm the effectiveness of the present method, a propulsion shafting with a diesel engine in a vessel was considered as the computational example of shafting in reciprocating machine. The results calculated by the present method were compared with those of the modal analysis method, the mechanical impedance method, and free vibration analysis.

Analysis of the Vibration Fatigue for the Diesel Engine and Reduction Gear Connecting Shaft in a Ship (선박용 감속기어-디젤엔진 연결축의 진동 피로파손 분석)

  • Han, HyungSuk;Lee, KyungHyun;Park, Sungho;Kim, ChungSik
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.5
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    • pp.407-413
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    • 2014
  • The diesel engine and reduction gear combination is one of the common propulsion system in a naval vessel. Since the diesel engine has torsional vibration caused by reciprocating motion of the mass and gas pressure force of the cylinder, high cycle torsional fatigue can be occurred. Therefore, ROK navy restricts the maximum stress of the propulsion shaft according to MIL G 17859D. In this paper, the root cause for the failure of the diesel engine and reduction gear connecting shaft occurred in typical naval vessel is investigated based on the measured bending and torsional moment according to MIL G 17859D procedure.

A Study on the Torsional Vibration of propulsion Shafting System with Controllable Pitch Propeller (가변익 프로펠러를 갖는 추진축계의 비틀림진동에 관한 연구)

  • 이돈출
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.5
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    • pp.626-634
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    • 1998
  • Controllable pitch propeller(CPP) is usually adopted for easy and effective engine controls of a ship in a port. Unfortunately the torsional vibration may occur by a certain variation of engine torque and the major resonance peak may exist within the maximum continuous rating(MCR) In these cases an additional stress concentration on the oil passages such as longitudinal slots notches and circular holes of an oil distributor shaft(ODS) occurs by the torsional vibration of the CPP shaft. In this paper an analysis for the fatigue limit of an ODS system of the 5S70MC engine in a crude oil carrier is done by applying FEM and empirical formulas. Furthermore the additional stress on the ODS is investigated by analyzing the torsional vibration of the shaft system and a control method in which a tuning damper is adopted is introduced in the case of the additional stress exceeds the fatigue limit. The validity of analysis method is verified by comparing the results acquired by an actual measurement of the vibratory torque for the above ODS

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Effects of Generator Retrofit on Torsional Natural Frequency of Turbine-generator Train and Study on Measurement Results (발전기교체로 인한 축계의 비틀림 고유주파수 영향 및 측정결과 고찰)

  • Lee, Hyuk-Soon;Yoo, Seong-Yeon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.3
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    • pp.267-273
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    • 2013
  • Recently, turbine-generators have been replaced for the integrity reinforcement and the efficiency improvement, also, the blade's failures of LP turbines due to torsional vibration have been reported. Excessive torsional vibrations can result in failures of components. The severity of torsional oscillations and stress depends upon the separation margin between the excitation frequencies and torsional natural frequencies. Therefore it is needed to measure the torsional natural frequencies after replacement of the components to conform the separation margin of torsional natural frequencies. In this study torsional vibration measurements were performed after LP turbine and generator replacement and the torsional natural frequencies for the turbine-generator train were calculated to evaluate the effects of generator replacement on torsional natural frequencies of turbine-generator train. It is expected that these evaluation results will be used effectively to identify the root causes of torsional vibration problems.

Development of Computer Program of Torsional Vibration Analysis for Design of Diesel Engine Propulsion Shafting (디젤기관 추진축계의 설계를 위한 비틀림 진동해석 전산프로그램의 개발)

  • Choi, M.S.;Moon, D.H.;Sim, J.M.
    • Journal of Power System Engineering
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    • v.7 no.2
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    • pp.23-28
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    • 2003
  • It is very important to analyze the torsional vibration for the propulsion shafting of ship. The authors have developed the transfer stiffness coefficient method(TSCM) as a vibration analysis algorithm. The concept of the TSCM is based on the successive transfer of stiffness coefficient. The effectiveness of the TSCM was verified through many applications. In this paper, the TSCM is applied to the torsional free vibration analysis for the propulsion shafting of an actual shin with a diesel engine. In order to calculate the additional torsional stresses of the propulsion shafting the torsional forced vibration for the shafting is analyzed by using both the modal analysis method and the results of the torsional free vibration analysis by the TSCM. The accuracy of the present method is confirmed by comparing with the vibration analysis results of engine maker.

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Study of Two Stroke Low Speed Diesel Engine Crankshaft Crack Phenomenon by Torsional Vibration Calculation & Measurement (비틀림 진동 계산 및 측정을 통해 고찰한 선박용 2행정 저속엔진 크랭크축 파단 현상)

  • Moon, Joung-Ha;Kim, Jeong-Ryul
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.6
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    • pp.452-461
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    • 2014
  • Two stroke low speed diesel engines that have many advantages such as high thermal efficiency and durability have been widely used for marine engine. However, it is also true that many problems have occurred due to the high explosion pressure and severe operating environment. Especially problems of shaft damage etc. intensively occurred due to the phenomenon of crankshaft exceeding the allowable stress, including the shaft vibration of the engine model in the early stage. In this study, the crankshaft fracture phenomenon of early engine model was evaluated and analyzed by using up-to-date torsional vibration calculation program and measurement instrument. And this was numerically shown.

Stress Analysis for Torsional Spring Box of Radial Dual Mass Flywheel (원판형 이중 질량 플라이휠의 비틀림 스프링 장치의 응력해석에 관한 연구)

  • 최병기;노승훈;남욱희;김광수;최성종;이춘열;채영석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.6
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    • pp.147-154
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    • 2003
  • Radial Dual Mass Flywheel(RDMF) is designed to reduce torsional vibration and noise occurring in automotive powertrain. In this paper, finite element method is used to evaluate stress level and critical area of the torsional spring box, a major part of RDNF system. In finite element analysis, both static and dynamic loadings are considered and it is found that the most critical spot is the welded zone of spring box. Also, fatigue test is performed and fractured surfaces are examined to find fatigue stress level by experiment.

A Study on the 2-node Torsional Vibration for Marine Diesel Engine Crankshaft (선박용 디젤기관 크랭크 축계의 2절 비틀림 진동에 대한 연구)

  • Choi, Moon-Keel;Park, Kun-Woo
    • Special Issue of the Society of Naval Architects of Korea
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    • 2008.09a
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    • pp.54-61
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    • 2008
  • With the development of computer program in calculation for torsional vibration of ship's propulsion shafting it has become possible to calculate all order's vibratory amplitude, vibratory torque, vibratory stress and synthesis value at all concerned revolutions by way of solving the vibratory equation directly. Though this kind of propulsion shafting vibration calculation method makes it possible to get generalized and precise result of calculation, the unexpected critical crankshaft torsional vibration has still appeared in maneuvering range of the engine. A close investigation has been carried out to find out the cause for the 2-node propulsion shafting torsional vibration of the crankshaft that exceeded the limitation value near the MCR 104rpm on the sea trial of the recently delivered 6000TEU class container vessel from HHIC. In conclusion, as the latest super-output engine with heavy crankshaft and propeller mass seems to be liable to 2-node torsional vibration of crankshaft, it is recommend that, in the design stage of propulsion shafting, its torsional vibration condition must be more carefully checked.

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