• Structural Engineering and Mechanics
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• v.24 no.5
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• pp.543-560
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• 2006

In this paper, first, the equations of motion for a rectangular isotropic plate have been derived. This derivation is based on the Von Karmann theory and the effects of shear deformation have been considered. Introducing an Airy stress function, the equations of motion have been transformed to a nonlinear coupled equation. Using Galerkin method, this equation has been separated into position and time functions. By means of the dimensional analysis, it is shown that the orders of magnitude for nonlinear terms are small with respect to linear terms. The Multiple Scales Method has been applied to the equation of motion in the forced vibration and free vibration cases and closed-form relations for the nonlinear natural frequencies, displacement and frequency response of the plate have been derived. The obtained results in comparison with numerical methods are in good agreements. Using the obtained relation, the effects of initial displacement, thickness and dimensions of the plate on the nonlinear natural frequencies and displacements have been investigated. These results are valid for a special range of the ratio of thickness to dimensions of the plate, which is a characteristic of the Multiple Scales Method. In the forced vibration case, the frequency response equation for the primary resonance condition is calculated and the effects of various parameters on the frequency response of system have been studied.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.8
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• pp.589-597
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• 2002

In this paper the nonstationary response of accelerating vehicle is firstly obtained by using nonstationary road roughness model in time domain. To get the result of nonstationary response in frequency domain, the maximum entropy method is used for Processing nonstationary response of vehicle in frequency domain. The three-dimensional transient maximum entropy spectrum (MES) of response is given.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.897-904
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• 2017

Optical equipment consists of various components, and a detector is mounted and operated on aircraft, tanks, and warships for target detection and classification. The structural stability and optical performance of aeronautical optical equipment operated at several kilometers of altitude are degraded owing to vibration generated in the aircraft. It is necessary to verify the structural stability and optical performance requirements of the equipment in vibration environment conditions during the design phase. In this study, vibration environment conditions were analyzed using a test standard and the measurements of the vibration generated in aircraft. The conditions were classified as endurance and operating vibration conditions for structural stability and optical performance verification, respectively. The structural stability was verified according to natural frequency analysis, response analysis for the endurance vibration condition, and static analysis. The optical performance was verified by applying the vibration response analysis results to the optical design/analysis program.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.04a
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• pp.89-94
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• 1994

Latticed domes take form a curved surface by arranged members with certain patterns. For this reason, it is possible for the characteristics of vibration to complicate by change of various parameters of dome; grid-pattern, boundary condition and ratio of radius-height etc. Therefore, it is important to clarify the effect by these parameters before generalized dynamic response analysis. So this study deals with free vibration analysis of latticed domes and makes clear an effect of shape coefficient, that is, geometrical characteristics of latticed domes, on the vibration characteristics.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.123-126
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• 2002

Acoustic vibration analysis has been performed using random vibration analysis module of MSC/NASTRAN to evaluate the safety of the composite satellite antenna structure under the acoustic pressure from the launch vehicle. It was found that maximum $3\sigma$ stress by acoustic excitation was less than allowable stress.

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.309-317
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• 2007

In this study, we conducted a vibration fatigue analysis of the lower control arm in a vehicle suspension system. The vehicle was driven during the tests so that the dynamic effects could be taken into account. The dynamic load of the frequency domain was superimposed on the frequency response analysis. We performed a virtual proving ground test using multi-body dynamics, along with a finite element analysis and fatigue life predictions. Shape optimization was also considered using the design of the experimental approach, and a response surface analysis was performed to improve the durability performance of the lower control arm. We identified the elements that had the most influence on the optimal shape of the finite element model and analyzed the sensitivity of those elements. Then the optimal points that minimized the amount of damage to the areas of interest were determined through a response surface analysis. The results suggested that the fatigue life of the model increased as its mass was not increased excessively, and demonstrated that these design procedures yielded an appropriate optimized lower control arm model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.797-800
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• 2006

The power flow analysis(PFA) can be effectively used to predict structural vibration in medium-to-high frequency ranges. In this paper, vibration experiment has been performed to observe the analytical characteristics of the power flow analysis of the vibration of a plate. In the experiment, the loss factor of the plate and the input mobility at a source point have been measured. The data for the loss factor has been used as the input data to predict the vibration of the plate with PFA. The frequency response functions have been measured over the surface of the plate. The comparison between the experimental results and the predicted results for the frequency responsefunctionshasbeenperformed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.970-977
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• 2008

This paper deals with the dynamic characteristics of the shaft with impeller model which is the most important part in developing the resin mixing machine. Through reverse engineering, it is possible to make the shaft with impeller geometry model which is necessary vibration characteristic analysis by commercial impeller. The natural frequency analysis and structural analysis using finite element analysis software are performed on the imported commercial shaft with impeller model. The most important fundamental natural frequency of the shaft with impeller model is around 14.5 Hz, which well agrees with modal testing. The most effective design variables were extracted by ANOM(analysis of means) and pareto chart. This paper presents approximation 2nd order polynomial as design variables using RSM(response surface methodology). Generally, RSM take 2 or 3 design variables, but this method uses 5 design variables with table of mixed orthogonal array. Further more, the analyzed result of the commercial shaft with impeller is to be utilized for the structural design of resin chock mixing machine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.810-812
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• 2008

Previously study on structural design of the main wing of the twenty-seat class WIG(Wing in Ground Effect) craft. In the final design, three spars construction was selected for safety in the critical flight load, and the Carbon-Epoxy material was selected for lightness and structural stability. In this study, the forced vibration analysis was performed on the composite main wing structure of the twenty-seat class WIG craft with two-stroke pusher type reciprocating engine. The vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the H-mode(horizontal mode), the V-mode(vertical mode) and the X-mode(twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the L-mode(longitudinal mode) with the oscillating propeller thrust which occurs in operation. According to the result of forced vibration analysis, structural design was modified to reduce the vibrations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.155-160
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• 1996

The vibration analysis of the automobiles has been a good subject for the engineers seeking solutions for more comfortable life. In the area of industrial vehicles, however, the seriousness of the vibration annoyance has not been considered so much. In this paper, a finite element model was built which was good for the low-frequency system(of fork-lift truck), and a forced vibration analysis was obtained for the component of 2n of harmonic orders from engine excitation to this model. Finally, a design optimization upon dynamic responses was made to minimize the vibration acceleration level at selected points representing the vibration level of the whole system.