• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.640-646
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• 2001

The torsional vibration monitoring system(TVM) for large diesel engines was developed and applied by manufacturers of torsional vibration damper, flexible coupling and diesel engine since 1990s. And demands of TVM have been steadily increased to operate safely engine and to extend maintenance interval of damper and flexible coupling. In this paper, the experimental methods and algorithms of TVM development which used the existing PC, turning wheel and speed sensors in ship are introduced.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
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• pp.99-107
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• 2000

With the results of calculation for natural frequencies, the forced reponses of coupled vibration of propulsion shafting were analysed by the modal analysis method. For the forced response analysis, axial exciting forces, axial damper/detuner, propeller exciting forces and damping coefficients were extensively investigated. As the conclusion of this study, some items are cleared as next. - The torsional amplitudes are not influenced by the radial excitation forces. - The axial vibrational amplitudes are influenced by the tangential exciting forces. An increase of amplitude is observed for the speed range in the neighbourhood of any torsional critical speed. - The coupling effect becomes larger if torsional and axial critical speed are closer together. - The axial exciting force of propeller is relatively strong, comparing with those of axial forces of cylinder gas pressure and oscillating inertia of reciprocating mechanism. Therefore, as a resume one can say, that- Torsional vibration calculation with the classical one dimension model is still valid. - The influence of torsional excitation at each crank upon the axial vibration is impotent, especially in the neighbourhood of a torsional critical speed. That means that the calculation of axial vibration with the classical one dimension model is insufficient in most of cases. - The torsional exciting torque of propeller can be neglected in most of cases. But, the axial exciting forces of propeller can not be neglected for calculating axial vibration of propulsion shafting.

• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.183-193
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• 1999

In the previous study, a module-type vibration analysis system using modular approach is developed for the purpose of analyzing the torsional vibration of vehicle driveline. In the present paper, the system is utilized to investigate the torsional vibration of the driveline of a middle duty truck. The driveline with driving condition is modeled and the torsional vibration response is simulated. The resonance 45Hz is found at engine speed 900rpm and the resultant vibration is very high. It shows favorable agreements with reference data. The effects of parameter change on torsional vibration are also investigated, so it is clarified that clutch characteristics, axle shaft stiffness are very influential on reduction of vibratio. So the countermeasure is proposed for the clutch characteristics. The reduction of torsonal vibration by 8rad/sec is obtained.

• 한국소음진동공학회논문집
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• 제23권3호
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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.

• Journal of Advanced Marine Engineering and Technology
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• 제25권3호
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• pp.563-572
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• 2001

With the results of calculation for natural frequencies the reponses of forced coupled vibration of propulsion shafting system were investigated by the modal analysis method. For the forced vibration response analysis, the axial exciting forces, the axial damper/detuner, propeller exciting forces and damping coefficients were extensively considered. As the conclusion of this study, some items are cleared as follows.-The torsional vibration amplitudes are not influenced by the radial excitation forces of the crank shaft. -The axial vibration amplitudes are influenced by the tangential exciting forces as well as the radial exciting forces of the crank shaft. The increase of the amplitudes is observed in the speed range at the neighbourhood of any torsional critical speed. 1The closer the torsional and axial critical speed. the larger coupling effect becomes. -The axial exciting force of propeller is relatively strong comparing with axial exciting forces of cylinder gas pressure and oscillating inertia of reciprocating mechanism. Therefore, the following conclusions are obtained. -Torsional vibration calculation with the classical one dimensional model is still valid. -The influence of torsional excitation at each crank upon the axial vibration is improtant. especially in the neighbourhood of a torsional critical speed. That means that the calculation of axial vibration with the classical one dimensional model is inaccurate in most of cases.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.722-728
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• 2001

Applying a general coupled lateral and torsional vibration finite element model of gear pair element this paper intends to look into in detail the coupled lateral and torsional vibration characteristics in a turbo-chiller rotor bearing system, having a bull-pinion speed increasing gear. Investigations have been carried out systematically by comparing the uncoupled and coupled analyses natural vibration frequencies and their mode shapes upon varying the gear mesh stiffness, and also by comparing the strain energies of lateral and torsional vibration modes. Results have shown that some modes may have coupled lateral and torsional mode characteristics as the gear mesh stiffness increases over a certain value, and moreover that their associated dominant modes may be different from their initial modes, i.e., the dominant mode changes from an initial torsional one to a lateral one or from an initial lateral one to a torsional one.

• 한국소음진동공학회논문집
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• 제26권4호
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• pp.436-442
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• 2016

This paper presents the torsional vibration isolation performance evaluation of a centrifugal pendulum absorbers (CPAs) that has a continuously varying resonance frequencies proportional to engine firing (excitation) order. CPAs are commonly used to suppress torsional vibrations in rotating machinery and internal combustion engines. In this study, they are employed on the current spring type torsional damper inside a torque converter of automotive vehicle. To evaluate the effectiveness of designed resonance tuning order, the torsional vibration transmissibility based on torque measurements with respect to different engine firing orders is experimentally measured with a lower-inertia dynamometer. The torsional vibration transmissibility with respect to different frequencies with engine order of 2 is also evaluated. It has been demonstrated that the significant vibration reduction over operational frequency range of interest can be achieved by attaching simple pendulums. Future research direction includes the study on theoretical analysis, improved design of pendulum etc.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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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.

• 한국소음진동공학회논문집
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• 제16권8호
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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.

• Journal of Advanced Marine Engineering and Technology
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• 제25권1호
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• pp.95-106
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• 2001

When the crankshaft of diesel engine has more than 3 throws, which are arranged in a different plane, its vibration induces coupled motions, especially the coupled torsional and axial vibration. Nowadays, the torsional vibration which is influenced rather weak than axial one, can be theoretically calculated fairly accurately, but theoretical calculation results of the axial vibration which is influenced strongly from torsional vibration is not so good. To get accurate calculation results of axial vibration, coupled axial-torsional vibration must be treated. In this investigation, coupled effects of vibration of diesel engine propulsion shafting are analyzed theoretically and some simple calculation methods are also studied. On this first report, effects of coupling on natural frequencies and their modes are mainly studied, setting the each mass in 4 degrees of freedom.