• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.241-246
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• 1997

Corrugation of railway track can be caused by the various dynamic behaviors of traveling wheels and track. In this paper, the coupled vibrations of traveling wheel and railway track are analyzed as the cause of corrugations. To analyze the coupled vibration, the track supported by the sleepers and the traveling wheels are identified to the elastically supported infinite beam and the spring-mass system which runs at constant speed. The Hertzian contact spring is considered between the infinite beam and spring-mass system. The dynamic responses of elastically supported infinite beam and spring-mass system are calculated. The cause and development of rail corrugation are discussed in the view point of contact force fluctuation affected by the elastic supports and the corrugated surface profile on the track. By the obtained results, the possibilities of resonance are checked between the excitation by the corrugated surface profile and the natural frequency of contact spring-mass system. It may be thought to a development of railway corrugation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.906-910
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• 2004

An analytical method for the free vibration of two annular plates coupled with water was developed by the Rayleigh-Ritz method. The two plates with unequal thickness are clamped along a rigid cylindrical vessel wall. It is assumed that the fluid bounded by a rigid cylindrical vessel is incompressible and non-viscous. The wet mode shape of the annular plates Is assumed as a combination of the dry mode shapes of the plates. The fluid motion is described by using the fluid displacement potential and determined by using the compatibility conditions along the fluid interface with the plate. Minimizing the Rayleigh quotient based on the energy conservation gives an eigenvalue problem. It is found that the theoretical results can predict well the fluid-coupled natural frequencies comparing with the finite element analysis result.

• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.169-180
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• 2008

As a major component of a power plant, a turbine generator must have sufficient reliability. Longer blades have lower natural frequency, thereby requiring that the design of the shaft and blade takes into account the coupling of the blade vibration mode, nodal diameter k=0 and k=1 with vibration of the shaft. The present work analyzes the coupling of the translation motion of the shaft with in-plane vibration of the blades with k=1 modes. At a rotational speed ${\Omega}_1=|{\omega}_s-{\omega}_b|$, the resonance of the blades has a relatively large amplitude. A violent coupled resonance was observed at a rotational speed ${\Omega}_2=|{\omega}_s+{\omega}_b|$. Resonance in blade vibration at ${\Omega}_1=|{\omega}_s-{\omega}_b|$ was experimentally confirmed.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.173-179
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• 2001

The torsional or axial critical vibration of the order coinciding with the number of propeller blades is simultaneously excited by the harmonic tangential or radial forces acting on the crank shaft and by the harmonic of the same order from the propeller. The exciting torque of propeller is relatively small comparing with that of crank side, but the exciting force of propeller rather larger than that of crank shaft. With this situation, the exciting force of propeller cannot neglect if the axial vibration of propulsion shafting is calculated. With the propeller in its optimal angular position, i.e. its excitation effect opposed to that of the engine, the stresses at the critical revolution will largely cancel themselves out. In this paper, a method of optimizing the angular propeller position with regard to torsional and axial vibration is studied. The optimal relative angle is determined theoretically by calculation results of coupled torsional-axial vibration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.11
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• pp.847-855
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• 2002

A rotary compressors are used most widely In air-conditioning systems. Noise and vibration of a rotary compressor is an important problems during turning on and off as well as during operating. To estimate the vibration occurring during turning on and off, vibration analysis of a motor-compressor coupled system is required. In this paper, through modeling the motor and solving the forces from the equations of motion of the moving parts, the analysis of vibration of the compressor taking into consideration of the effects of motor and moving parts was performed. The accelerations of accumulator during turning on. turning off and operation are simulated. And simulated accelerations are compared with those of experimental data.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.1
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• pp.15-22
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• 2003

Beams are often subject to bending-torsion coupled vibration due to mass coupling and/or stiffness coupling. This paper proposes a dynamic analysis method using the exact dynamic element for bending-torsion coupled vibration of general plane beam structures with joints. The exact dynamic element matrix for a bending-torsion coupled beam is derived, and the detailed procedure of using the exact dynamic element matrix is also presented. Three examples are provided for validating and illustrating the proposed method. The numerical study proves the proposed method to be useful for dynamic analysis of bending-torsion coupled beam structures with joints.

• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.13-24
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• 2012

There are a large number of papers in the literature dealing with the free vibration analysis of single/multi-span uniform beam with multiple spring-mass systems, but that of coupled multi-span beams carrying spring-mass attachments is rare. In this note, free vibration analysis of a weakly coupled beam system with spring-mass attachments is conducted. The mode localization and frequency loci veering phenomena of the coupled beam system are investigated. Studies show that for weakly coupled beam system with spring-mass attachments, the mode localization and frequency loci veering will occur once there is a disorder in the system.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.3
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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.

• Structural Engineering and Mechanics
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• v.41 no.1
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• pp.67-81
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• 2012

Differential Quadrature Method (DQM) is a powerful method which can be used to solve numerical problems in the analysis of structural and dynamical systems. In this study the governing equation which represents the free vibration of coupled shear walls is solved using the DQM method. A one-dimensional model has been used in this study. At the end of study various examples are presented to verify the accuracy of the method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.318-321
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• 2005

In vibro-acoustic analysis, the commercial CAE tools, such as SYSNOISE, is usually used to take into account of the coupled effects of fluid acoustics and structural vibration. The acoustic field can be solved by either FEM or BEM, while the vibration field is usually solved by FEM. The interior or exterior acoustic problems with the coupled effects of the structural boundary could be solved by the commercial tools. The commercial tools, however, could not solve the problems in case that both the interior and exterior acoustic field is coupled with the structural boundary. In this paper, a realistic method based on FEM/BEM coupling scheme is presented to analyze the acoustic radiation from the internal source in a chamber to external acoustic field through elastic structural boundary. Several numerical examples are implemented to validate the developed program.