• Journal of KSNVE
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• v.10 no.5
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• pp.806-810
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• 2000

This paper presents a practical method for reduction of interior noise and improvement of sound quality in compartment of passenger car. The tested vehicle has a booming noise problem at rear passenger seats. In order to identify the transfer path of interior noise, the running modal analysis, the vibro-acoustic frequency transfer response and the noise path analysis are systematically employed. Using these various methods, it has been founded that the rear part of the roof of the test car was a noise source for the booming noise. Through the modification of the roof, the booming noise has been reduced and sound quality inside car also has been improved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.323-326
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• 2004

In these days, gear whine noise of the axle and transmission is getting more important for reduction of vehicle noise, because major noise of vehicle was reduced. Therefore, in this paper, axle noise and vibration is measured, and then the modal analysis and running modal analysis is applied for reduction of axle gear whine noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.180-185
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• 2005

Gear whine noise of the axle and transmission is getting more important for reduction of vehicle noise, because major noise of vehicle was reduced. Therefore, in this paper, axle noise and vibration is measured, then the modal analysis and running modal analysis is applied for identification of axle gear whine noise. And To reduce axle noise, Various structural modifications are performed by using FEM and BEM techniques.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.582-592
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• 2006

This paper presents experimental and analytic methods to reduce interior noise generated by car axle. The test vehicle has a whine noise problem at passenger seats. In order to identify transfer path of interior axle noise, the vibration path analysis, the modal analysis and running modal analysis are systematically employed. By using these various methods, it has been founded that the interior noise generated by car axle was air borne noise. To reduce and predict axle noise, various structural modifications are performed by using FEM and BEM techniques, respectively. Through the modification of the axle structure, the air borne noise of the axle was reduced 3$\sim$4 dBA level.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.69-82
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• 1992

Vibration of intake menifold is important as it could worsen the noise levels radiated from surface itself and support bracket, and it eventually leads to the failures of a Throttle Position Sensor and an Idle Air Control Valve. In this study, structural modification method is proposed to reduce structural vibration of an intake manifold system. At first, vibration problems are identified through tests on a running engine. Then modal data acquired by modal testing and finite element analysis are helpful to understand vibration mechanism of the system, and used as the design guide when structural modifications are attempted. After the system model is validated by comparison of the modal data obtained from analysis and experiment, iterative calculations are performed to find optimized structure of the system by finite element analysis. As a result, a newly designed plenum bracket is suggested in such a way that the intake manifold is stiffened, and that design of the support bracket is suggested in such a way that the intake manifold is stiffened, and that design of the support bracket is changed in terms of bolting position, thickness, shape, and minimum weight increase. Finally, it is shown that a new design achieves a significant reduction of vibration of an intake manifold system and it is confirmed by tests on a running engine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.358-363
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• 1997

The Operational Deflection Shape designates the motion pattern by which a structure vibrates under a specific operating condition. Modal Analysis is usually tested under test bench, but Operational Deflection Shape can be measured directly under real operating condition. It provide useful information for trouble-shooting and aid understanding and evaluation of the absolute dynamic behaviour of a machine or component. In this paper, It is analysed Excavator Upper Frame using Operating Deflection Shape.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.891-896
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• 2007

Noise radiated from the powertrain is an important factor of the vehicle interior noise. In this paper, Finite Element(FE) model and Boundary Element(BE) models were created. The FE model was updated by doing a correlation between experimental modal analysis(EMA) values and finite element analysis(FEA) values. Main bearing forces were calculated using a running modal data. The forced vibration analysis was simulated using the software MSC/NASTRAN, and the radiated noise was predicted using the software LMS/VIRTUAL.LAB.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.22-27
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• 2003

The running safety of the rolling stock depends on the design characteristics and the contact condition between wheel and railway. In this study, the effect of the conicity of wheel tread on the running safety is analyzed. The modal analysis results in $0.5\~0.6Hz$ natural frequency with lateral modes. However, the frequency analysis for the running simulation shows the frequency components near 1Hz. The running simulation shows that the KTX with GV40 wheel has less lateral vibration than that of XP55 as the KTX goes higher speed.

• International Journal of Aerospace System Engineering
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• v.8 no.1
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• pp.1-13
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• 2021

Contra-rotating fan is comprised of two rotors which are rotating in the opposite direction. The fan stages are named rotor-1 and rotor-2. Benefits from the use of contra rotation are in terms of better efficiency and improved thrust to weight ratio. Failure of contra-rotating fan stage blade in-service results in safety risks, repair costs, and revenue losses. This paper focuses on the vibration analysis and one way fluid-structure interaction of high aspect ratio, low speed contrarotating fan rotors. Modal analysis and modal pre-stress analysis of contra-rotating fan rotors were carried out to calculate the natural frequencies, One way fluid-structure interaction (FSI) was carried out where the computational analysis of the blades was performed using ANSYS CFX. The boundary conditions for CFD analysis were considered from the actual experimental velocity flow field at the inlet and pressure outlet. Based on the results obtained from the CFD analysis, the structural analysis such as deformation and Von-Misses stresses was carried out by using the finite element method (FEM) with ANSYS. The results provide necessary guidelines for the safe running of the contra-rotating fan. The analysis also will be helpful to understand the change of flow behavior due to a rotor deformation.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.683-701
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• 2016

Safety is the prime concern for a high-speed railway bridge, especially when it is subjected to a collision. In this paper, an analysis framework for the dynamic responses of train-bridge systems under collision load is established. A multi-body dynamics model is employed to represent the moving vehicle, the modal decomposition method is adopted to describe the bridge structure, and the time history of a collision load is used as the external load on the train-bridge system. A (180+216+180) m continuous steel trussed-arch bridge is considered as an illustrative case study. With the vessel collision acting on the pier, the displacements and accelerations at the pier-top and the mid-span of the bridge are calculated when a CRH2 high-speed train running through the bridge, and the influence of bridge vibration on the running safety indices of the train, including derailment factors, offload factors and lateral wheel/rail forces, are analyzed. The results demonstrate that under the vessel collision load, the dynamic responses of the bridge are greatly enlarged, threatening the running safety of high-speed train on the bridge, which is affected by both the collision intensity and the train speed.