• 한국소음진동공학회논문집
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• 제15권1호
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• pp.72-80
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• 2005

Recent studies have dealt with brake squeal in terms of the coupled vibration of brake component parts. In this paper, we assemble the mode models derived from FE analysis of the individual components of the drum brake system into the system model by considering the friction interaction of the lining and drum at the interface. The validity of the component models are backed up by the experimental confirmation work. By scrutinizing the real parts of the complex eigen-values of the system, the unstable modes, which may be strong candidate sources of squeal noise, are identified. Mode participation factors are calculated to examine the modal coupling mechanism. The model predictions for the unstable frequencies pointed well the actual squeal noise frequencies measured through field test. Sensitivity analysis is also performed to identify parametric dependency trend of the unstable modes, which would indicate the direction for the squeal noise reduction design. Finally, reduction of the squeal noise tendency through shape modification is tried.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.526-531
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• 2011

A dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train. Meanwhile, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it seems important to provide an optimal design scheme incorporating sound packages such as dash isolation pad and carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. The system taken into account in this paper is a dash panel component of a sedan, which includes A pillar, front side member, dash panel and the corresponding sound packages. Design variables such as panel thickness and sound package layers are investigated how they are related for the better radiation performance (i.e. structure-borne) and sound transmission loss (i.e. air borne).

• Tribology and Lubricants
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• 제35권1호
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• pp.71-76
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• 2019

The differential planetary gear reducer as a main component of the concrete mixer driving mechanism requires a strong torque to mix concrete compounds. As this component is currently dependent on imports, it is necessary to develop it by conducting a study on vibration analysis and the resonance problem. The noise and vibration of a concrete mixer reducer increase owing to the transmission error of planetary gears, and the damage of components occurs owing to the problems in design and production. In this study, the tooth-passing frequency is calculated to evaluate the noise and vibration of a mixer reducer, and a fast Fourier transform (FFT) analysis is conducted through a vibration test using an acceleration sensor. The vibration of the reducer is measured at three points of input and output of the shaft and planetary gear housing with fixed and variable revolutions per minute. The operating conditions of gears and bearings are evaluated by performing the FFT analysis, and the resonance problem is verified. The results show that No. 1 pinion and ring gears revolve disproportionately. The amplitude values appear high, and the wear of tooth faces occur in tooth-passing frequencies and harmonic components of No. 1 and No. 2 pinion-ring gears. Therefore, we conclude that design changes in the reducer and a correction of tooth profiles are required.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.383-389
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• 2013

Rotor system is a very important part which produces lift, thrust and control force in helicopter. Component of rotor system must endure various flight load for the required life. In helicopter rotor system, bearingless rotor system is the highest technology rotor system compare with articulated and hingeless rotor system. Baaringless rotor system is not include mechanical flap hinge, lag hinge and pitch bearing. Bearingless rotor component flexbeam which made by composite material has conduct hinge and bearing role instead of mechanical flap hinge, lag hinge and pitch bearing. These characteristics has less part number and lass weight than others. In this paper, conduct safe life analysis of bearingless composite component flexbeam and torque tube applying to utility helicopter load condition.

• 한국정밀공학회지
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• 제8권3호
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• pp.73-81
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• 1991

There have been many studies on chatter vibration in machining but there seems to be no regulations to decide the commencing point of chatter objectively. The development of an objective method which can estimate and detect chatter commencement is very much in need for automatic manufacturing systems, dynamic performance tests for machine tools, so on. In this study, therefore, the estimation and the in-process detection of chatter have been experi- mentally investigated for the turning process. As a result, the commencing point of chatter can be decided from the behavior of the maximum amplitude of the dynamic component of cutting force, where the maximum amplitude is suddenly increasing with the chatter commencement. Then the commencing point of chatter can be estimated practically by this method before the occurrence of excessive vibration. Also, it is possible to detect the occurence of chatter vibration through the in-process measurement, by monitoring the maximum amplitude of the dynamic component of cutting force.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.994-995
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• 2014

Supporting stiffness of seats is an important component affecting dynamic characteristics cognized by a passenger. To analyze dynamic characteristic of a seat for vehicles operating on various road conditions, the seat vibration from road irregularity should be understood and compared. In this study, the seat is analyzed as distributed supporting system. The dynamic stiffness is measured using masses. The characteristic of the seats is analyzed by measuring distributed dynamic stiffness. The distributed dynamic stiffness of the seat is estimated on various locations and the effects of each component such as spatial distribution, compression level and vibration amplitude are analyzed. The influence of seat cover, elastic support and flexible polyurethane foam on the measured stiffness was analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.474-476
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• 2013

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.533-539
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• 2001

In this research, design Sensitivity Analysis is presented for commercial vehicle such as large scale structural system. The proposed method is based on vibration analysis of the total structure and design sensitivity to identify the contribution factor of the component structure to the total system structure. In addition, approximated equations derived from response surface method are used for representative section properties of the thin walled beams.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.615-620
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• 2005

Vibration in Engine module could be reduced by introducing a balance shaft module which has one or more unbalanced rotors. The unbalanced rotor is unbalanced in one direction that act as a opposite direction of the inertia force or moment triggered by engine component so that the largest order factor in vibration is efficiently decreased The ability of balance shaft to reduce the order element of engine component is investigated by a vehicle testing that is focused on comparing the vibration with balance shaft to that of without balance shaft. One of the commonly adapted balance shaft is tested by modal scheme for indemnifying the dynamic characteristics and an, the modal information is used for a clue to design the balance shaft module. The essential equation deriving the design parameters of unbalanced rotor is also presented for two cases, 3 in-ling and 4 in-ling cylinder model. Finally, the overall design process is explained with flow chart.

• 동력기계공학회지
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• 제19권5호
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• pp.52-59
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• 2015

This paper is presented for the free vibration of a conical shell with annular plates or circular plate using the transfer of influence coefficient. The governing equations of vibration of a conical shell, including annular plate, are written as a coupled set of first order differential equations by using the transfer matrix of the shell. Once the transfer matrix of a single component has been determined, the entire structure matrix is obtained by the product of each component matrix and the joining matrix. The natural frequencies and the modes of vibration were calculated numerically for joined conical-annular plates. The validity of the present method is demonstrated through simple numerical examples, and through comparison with the results of finite element method, transfer matrix method and ANSYS. The conclusion show that the present method can accurately obtain natural vibration characteristics of the conical shell with annular or circle end plates.