• Title/Summary/Keyword: longitudinal-torsional vibration

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FEA of Rotary Type Ultrasonic Vibrator using Longitudinal-Torsional Vibration (종-비틀림 진동모드를 이용한 회전형 초음파 진동자의 유한요소 해석)

  • Jeong, Dong-Seok;Park, Tae-Gone;Kim, Myung-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.601-604
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    • 2002
  • In this paper bolt-tightened Langevin type vibrator was designed using longitudinal-torsional vibration. These two vibrations make rotary displacement at the end of the vibrator. ANSYS was used to determine shape and dimension of the vibrator in addition to resonant frequency, displacement and stress distribution. This kind of vibrator can be applied for a brakeless and gearless rotary motor which has high torque at low speed.

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Torsional modal testing of a non-ferromagnetic shaft by magnetostrictive patch transducers (자기변형 패치 트랜스듀서를 이용한 비자성 축의 비틀림 모달 테스팅)

  • Cho, Seung-Hyun;Han, Soon-Woo;Park, Chan-Il;Kim, Yoon-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1159-1164
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    • 2006
  • Torsional vibration is an important vibration mode when shafts, cylinders and pipes are considered. However, the modal testing of torsional vibrations is not an easy job to carry out because of the lack of proper transducers. This work presents a new torsional vibration transducer based on the magnetostrictive principle and its application to torsional modal testing. The transducer is so designed as to generate/measure only torsional vibrations excluding other vibration modes such as longitudinal and bending vibrations. The transducer is composed of ferromagnetic patches bonded to a test structure, permanent magnets, and a solenoid. Though patches and magnets are bonded to a structure, torsional vibrations are generated and measured wirelessly by a solenoid encircling a test structure. The proposed transducer works even at considerably high frequencies, say, tens of kilohertz. Furthermore, the transducer can be manufactured at a low price. To check the performance of the proposed method, the torsional modal testing on a hollow aluminum shaft was conducted. The results, such as eigenfrequencies, obtained by the proposed transducer agreed favorably with theoretical results.

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Torsional Modal Testing of a Non-ferromagnetic Shaft by Magnetostrictive Patch Transducers (자기변형 패치 트랜스듀서를 이용한 비자성 축의 비틀림 모달 테스팅)

  • Cho, Seung-Hyun;Han, Soon-Woo;Park, Chan-Il;Kim, Yoon-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.8 s.113
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    • pp.879-885
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    • 2006
  • Torsional vibration is an important vibration mode when shafts, cylinders and pipes are considered. However, the modal testing of torsional vibrations is not an easy task to carry out because of the lack of proper transducers. This work presents a new torsional vibration transducer based on the magnetostrictive principle and its application to torsional modal testing. The transducer is so designed as to generate/measure only torsional vibrations excluding other vibration modes such as longitudinal and bending vibrations. The transducer is composed of ferromagnetic patches bonded to a test structure, permanent magnets, and a solenoid. Though patches and magnets are bonded to a structure, torsional vibrations are generated and measured wirelessly by a solenoid encircling a test structure. The proposed transducer works even at considerably high frequencies, say, tens of kilohertz. Furthermore, the transducer can be manufactured at a low price. To check the performance of the proposed method, the torsional modal testing on a hollow aluminum shaft was conducted. The results, such as eigenfrequencies, obtained by the proposed transducer agreed favorably with theoretical results.

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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Longitudinal Vibration Mechanism of Grouted PSC Tendon (부착식 PSC 텐던의 종진동 메카니즘)

  • Kim, Byeong Hwa;Jang, Jung Bum;Lee, Hong Pyo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.3A
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    • pp.261-267
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    • 2011
  • This study reveals the longitudinal vibration mechanism of tendon embedded in a prestressed concrete. The extensional and torsional displacements of the strand are coupled, and the applied prestress level of tendon affects not only axial rigidity but also torsional rigidity. Measuring the elastic wave velocity of tendon, the applied prestress level of tendon could be evaluated. This is because the elastic wave velocity is a function of extensional and torsional rigidity. Using the experimental results for the six prsteressed concrete beams with different prestress levels, the longitudinal vibration mechanism and the effect of prestress level have been examined. To estimate the system ridigities of tendon, a system identification algorithm has been newly developed. The estimated system rigidities have been compared with the available results of related previous study.

A Study on the Longitudinal Hull Girder Vibration of a 73,000 Deadweight Bulk Carrier (73,000톤 산적화물선의 선체거더 종진동 현상분석)

  • Jong-Gug Bae;Kyoon-Yang Chung
    • Journal of the Society of Naval Architects of Korea
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    • v.32 no.2
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    • pp.103-107
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    • 1995
  • Longitudinal hull girder vibration has not been occurred severely since 1960's. However, recent low speed diesel driven ships equipped with overcritical shafting system, can be excited heavily in longitudinal direction by shaft axial farce coupled with torsional vibration. In this study the characteristics of longitudinal hull girder vibration of a 73,000 deadweight bulk carrier were investigated through onboard measurement, exciter test, and 3-D FEM analysis. Results showed that the longitudinal hullgirder vibration may occur in the ship which is not set up the barred speed range in engine operation. Moreover, this vibration occurs. only during the low speed voyage in harbour depending upon the ship loading condition.

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On Development of Vibration Analysis Algorithm of Beam with Multi - Joints(II) (다관절 보의 진동해석 알고리즘 개발에 관한 연구 (II))

  • 문덕홍;최명수;홍숭수;강현석
    • Journal of Advanced Marine Engineering and Technology
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    • v.21 no.3
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    • pp.256-266
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    • 1997
  • The authors apply the transfer influence coefficient method to the 3. dimensional vibration analysis of beam with multi - joints and formulate a general algorithm to analyse the longitudinal, flexural and torsional coupled forced vibration. In this paper, a structure which is mainly found in the robot arms, cranes and so on, has some crooked parts, subsystems and joints, but has no closed loop in this system. It is modeled as the beam of a distributed mass system with massless translational, rotational and torsional springs in each node, and joint elements of release or roll at node which the displacement vector is discontinuous. The superiority of the present method to the transfer matrix method in the computation accuracy was confirmed from the numerical computation results. Moreover, we confirmed that boundary and intermediate conditions could be controlled by varying the values of the spring constants.

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On Development of Vibration Analysis Algorithm of Beam with Multi-Joints(II) (다관절 보의 진동해석 알고리즘 개발에 관한 연구 II)

  • 문덕홍;최명수;홍승수;강현석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.10a
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    • pp.203-209
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    • 1996
  • The authors apply the transfer influence coefficient method to the 3-dimensional vibration analysis of beam with multi-joints and formulate a general algorithm to analysis the longitudinal, flexural and torsional coupled forced vibration. In this paper, a structure, which is mainly founded in the robot arms, cranes and so on, has some crooked parts, subsystems and joints but has no closed loop in this system. It is modeled as the beam of a distributed mass system with massless translational, rotational and torsional springs in each node, and joint elements of release or roll at which node the displacement vector is discontinuous. The superiority of the present method to the transfer matrix method in the computation accuracy was confirmed from the numerical computation results. Moreover, we confirmed that boundary and intermediate conditions could be controlled by varying the values of the spring constants.

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On Development of Vibration Analysis Algorithm of Beam with Multi-Joints (다관절 보의 진동해석 알고리즘의 개발에 관한 연구)

  • 문덕홍;여동준;최명수
    • Journal of Advanced Marine Engineering and Technology
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    • v.18 no.5
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    • pp.68-77
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    • 1994
  • The authors apply the transfer influence coefficient method to the 3-dimensional vibration analysis of beam with multi-joints and formulate a general algorithm to analysis the longitudinal, flexural and torsional coupled free vibration. In this paper, the structure, which is mainly founded in the robot arms, cranes and so on, has some crooked parts, subsystems and joints but has no closed loop in this system. It is modeled as the beam of a distributed mass system with massless translational, rotational and torsional springs in each node, and joint elements of release or roll at which node the displacement vector is discontinuous. The superiorty of the present method to the transfer matrix method in the computation accuracy was confirmed by the numerical computation results. Moreover, we confirmed that boundary and intermediate conditions could ve controlled by varying the values o the spring constants.

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Probabilistic Analysis of Coupled Axial and Torsional Vibration of Marine Diesel Propulsion Shafting System (선박디젤추진축계 종.비틂연성진동의 확률적 해석)

  • S.Y. Ahn
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.3
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    • pp.71-78
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    • 1998
  • Recently, modern long-stroke diesel engines with small number of cylinders have been installed for energy saving and simpler maintenance. These kinds of low speed diesel engine produce large torsional vibration in the shafting, which induces the excessive vibratory stresses in the shafting and large propeller thrust variation. This thrust variation excites vibrations of the shafting and superstructure in the longitudinal direction. Up to now the deteriministic analysis of coupled vibration of marine shafting system has been performed. In this paper probabilistic analysis method of the marine diesel propulsion shafting system under coupled axial and torsional vibrations is presented. For the purpose of this work, the torsional and axial vibration excitations of engine and propeller are assumed to be probabilistic while the lateral excitation is assumed to be deterministic. The probabilistic analysis is based on a response surface and Monte-Carlo simulation. Numerical results based on the proposed method are compared with results calculated using the conventional deterministic analysis method. The results obtained make it clear that the proposed method gives a substantial increase in information about shafting behaviour as compared with the deterministic method.

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