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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society for Noise and Vibration Engineering
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The Korean Society for Noise and Vibration Engineering
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Volume & Issues
Volume 17, Issue 12 - Dec 2007
Volume 17, Issue 11 - Nov 2007
Volume 17, Issue 10 - Oct 2007
Volume 17, Issue 9 - Sep 2007
Volume 17, Issue 8 - Aug 2007
Volume 17, Issue 7 - Jul 2007
Volume 17, Issue 6 - Jun 2007
Volume 17, Issue 5 - May 2007
Volume 17, Issue 4 - Apr 2007
Volume 17, Issue 3 - Mar 2007
Volume 17, Issue 2 - Feb 2007
Volume 17, Issue 1 - Jan 2007
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Case Study on Hydroelastic Vibration of Plate for Various Bounded Fluid Field
Choi, S.H. ; Jo, H.D. ; Kim, K.S. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 3~9
DOI : 10.5050/KSNVN.2007.17.1.003
In this paper, a numerical case study is carried out on the hydroelastic vibration of rectangular plate with various fluid field. It is assumed that the tank wall is clamped along the plate edges. The VMM(virtual mass method) of Nastran is used for the simulation of fluid domain and calculating natural frequency of fluid-coupled structure. In this paper, natural frequencies are calculated and compared for rectangular plates with various fluid field such as infinite fluid and finite fluid, length change of finite fluid field and various fluid contacting conditions.
Stability Analysis of Pipe Conveying Fluid with Crack
Son, In-Soo ; Ahn, Tae-Su ; Yoon, Han-Ik ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 10~16
DOI : 10.5050/KSNVN.2007.17.1.010
In this paper, the dynamic stability of a cracked simply supported pipe conveying fluid is investigated. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid due to the coupled mode(modes combined) is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Galerkin method. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The stiffness of the spring depends on the crack severity and the geometry of the cracked section. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. This results of study will contribute to the safety test and a stability estimation of the structures of a cracked pipe conveying fluid.
Response Analysis of 3-dimensional Floating Structure Using Beam Transformation
Hong, Sa-Young ; Kyoung, Jo-Hyun ; Cho, Seok-Kyu ; Kim, Byoung-Wan ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 17~23
DOI : 10.5050/KSNVN.2007.17.1.017
In this paper, the modified direct method employing beam transformation technique is proposed in order to efficiently calculate hydroelastic responses of floating structure. Since the proposed method expresses the displacements of three-dimensional structure with those of transformed beam which leads to small number of equations of motion, the method is numerically efficient compared to the conventional direct method. To verify the efficiency of the proposed method, a 500 m-long floating structure under wave loads is considered in numerical example. Displacements, bending moments, torsion moments and shear forces are calculated and computing time is examined. The results are also compared with those of the conventional direct method.
Finite Element Modal Analysis of a Spinning Flexible Disk-spindle System Considering the Flexibility of Supporting Structures and an Head-suspension-actuator in a HDD
Seo, Chan-Hee ; Lee, Ho-Sung ; Jang, Gun-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 24~32
DOI : 10.5050/KSNVN.2007.17.1.024
This paper presents a finite element method to analyze the free vibration of a flexible HDD composed of the spinning disk-spindle system with fluid dynamic bearings(FDBs), the head-suspension-actuator with pivot bearings, and the base plate with complicated geometry. Experimental modal testing shows that the proposed method well predicts the vibration characteristics of a HDD. This research also shows that even the vibration motion of the spinning disk corresponding to half-speed whirl and the pure disk mode are transferred to a head-suspension-actuator and base plate through the air bearing and the pivot bearing consecutively. The proposed method can be effectively extended to investigate the forced vibration of a HDD and to design a robust HDD against shock.
Analysis of the Magnetic Force and Torque of a Rotatory Two-phase Transverse Flux Machine
Park, Nam-Ki ; Chang, Jung-Hwan ; Jang, Gun-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 33~40
DOI : 10.5050/KSNVN.2007.17.1.033
Rotatory two-phase transverse flux machine(TFM) is a relatively new type of motor with high power density, high torque, and low speed in comparison to conventional electrical motors. However, it has some shortcomings,.i.e. complex construction and high possibility of the magnetically induced nitration due to its inherent structure. This Paper investigates the characteristics of the magnetic force and the torque in the rotatory two-phase TFM by using the 3-D finite element method and the spectral analysis. This research shows that the average torque decreases and that the torque ripple increases as the phase delay increases. It also shows that the unbalanced magnetic force is one of the dominant excitation forces in this machine. And it proposes a new topology of rotatory two-phase TFM to eliminate the unbalanced magnetic force.
Acoustic Scattering from Circular Cylinder by Periodic Sources
Lee, Duck-Joo ; Kim, Yong-Seok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 41~47
DOI : 10.5050/KSNVN.2007.17.1.041
Scattering fields of two dimensional acoustic waves by a circular cylinder are investigated. The present numerical approach for the acoustic scattering problem has difficulties of numerical robustness, long-time stability and suitability of far-field boundary treatments. The time-dependent periodic acoustic source is used to analyze Interference patterns between incident waves and waves reflected by the cylinder. Characteristic boundary algorithms coupled with 4th order Modified-Flux-Approach ENO(essentially non-oscillatory) schemes are employed in generalized coordinates to examine the effect of the wane frequency on the interference patterns. Non-reflecting boundary conditions, which is crustal for accurate computations of aeroacoustic problems, are used not to contaminate scattering fields by reflected waves at the outer boundary. Computed scattering fields show the circumferential acoustic modes generated by interacting between acoustic sources and scattered waves. At a lower frequency, the wave passes almost straight through the cylinder without Interacting with circular cylinder. Simulation results are presented and compared with the analytic solution. Computed RMS-pressure distribution on the cylinder wall is good agreement with exact solution.
Phase Change for One to One Resonance of Nonlinear Cantilever Beam
Pak, Chul-Hui ; Cho, Chong-Du ; Cho, Ki-Cheol ; Kim, Myoung-Gu ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 48~54
DOI : 10.5050/KSNVN.2007.17.1.048
The cantilever beam with nonlinearity has many dynamic characteristics of nonlinear vibration. Nonlinear terms of a flexible cantilever beam include inertia, spring, damping, and warping. When the beam is given basic harmonic excitation, it shows planar and nonplanar vibrations due to one-to-one resonance. And when the one-to-one resonance occurs, the flexible beam shows different behaviors in those vibrations. For the one-to-one resonance occurring in each mode, the phase value of the planar vibration is different from that of the nonlinear vibration. This paper investigates the phase change and the phase difference between such planar and nonplanar vibrations which are caused by one-to-one resonance.
An Investigation of Power Flow Mechanism in Beam-plate Built-up Structures with an Energy-absorbing Plate
Yoo, Ji-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 55~64
DOI : 10.5050/KSNVN.2007.17.1.055
In the built-up structure consisting of a stiff beam and a flexible plate, Grice showed that the plate behaves as an energy absorber in narrow frequency bands(called plate blocking effect). This paper deals with such beam-plate coupled structures, where the plate is an energy absorber and the excited beam is an energy path. It is found that such energy dissipation can occur in the relatively broad bands, if different stiffnesses are used in the rectangular plate. It was experimentally verified by Heckl that the energies in terms of one-third octave band averages transferred to the plate(or dissipated in the plate) increase for increased plate damping. This Paper, however, shows that the energy absorption suddenly reduces at the certain narrow frequency bands where the plate damping effect upon the coupled beam is maximum. Also, in order to minimize energy transfer through the beam in terms of one-third octave band averages, it is advantageous to increase the plate damping closer to the excitation point All these results are based on the wane method.
Tolerance Analysis for Natural Frequencies of Multi-body Systems in Dynamic Equilibrium State
Eom, Seung-Man ; Choi, Dong-Hwan ; Yoo, Hong-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 65~71
DOI : 10.5050/KSNVN.2007.17.1.065
Tolerance analysis method for natural frequencies of multi-body systems having a equilibrium position is suggested in this paper. To perform the tolerance analysis, the Monte-Carlo Method is conventionally employed. However, the Monte-Carlo Method has some weakness; spending too much time for analysis and having a low accuracy and hard to converge in the dynamical unstable area. To resolve these problems, a tolerance analysis method is suggested in this paper. Sensitivity equations of natural frequencies are derived at the equilibrium position. By employing the sensitivity information of mass, damping and stiffness matrices, the sensitivity of natural frequencies can be calculated.
Performance Enhancement of Pneumatic Vibration Isolation Tables in Low Frequency by Active Control
Shin, Yun-Ho ; Oh, Ki-Yong ; Lee, Jeung-Hoon ; Kim, Kwang-Joon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 72~79
DOI : 10.5050/KSNVN.2007.17.1.072
As environmental vibration requirements on precision equipment become more stringent, use of pneumatic isolators has become more popular and their performance is subsequently required to be further improved. Dynamic performance of passive pneumatic isolators is related to various design parameters in a complicated manner and, hence, is very limited especially in low frequency range by volume of chambers. In this study, an active control technique, so called time delay control which is considered to be adequate for a low frequency or nonlinear system, is applied to a single chamber pneumatic isolator. The procedure of applying the tine delay control law to the pneumatic isolator is presented and its effectiveness in enhancement of transmissibility performance is shown based on simulation and experiment. Comparison between passive and active pneumatic isolators is also presented.
A Study for Structural Damage Identification Method Using Genetic Algorithm
Woo, Ho-Kil ; Choi, Byoung-Min ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 80~87
DOI : 10.5050/KSNVN.2007.17.1.080
In this paper, a method for identifying the location and extent of a damage in a structure using residual forces was presented. Element stiffness matrix reduction parameters in a finite element model were used to describe the damaged structure mathematically. The element stiffness matrix reduction parameters were determined by minimizing a global error derived from dynamic residual vectors, which were obtained by introducing a simulated experimental data into the eigenvalue problem. Genetic algorithm was used to get the solution set of element stiffness reduction parameters. The proposed scheme was verified using Euler-Bernoulli beam. The results were presented in the form of tables and charts.
Response Spectra of Structure Installed Frictional Damping System
Park, Ji-Hun ; Youn, Kyung-Jo ; Min, Kyung-Won ; Lee, Sang-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 1, 2007, Pages 88~94
DOI : 10.5050/KSNVN.2007.17.1.088
Structures with additional frictional damping system have strong nonlinearity that the dynamic behavior is highly affected by the relative magnitude between frictional force and excitation load. In this study, normalized response spectra of the structures with non-dimensional friction force are obtained through nonlinear time history analyses of the mass-normalized single degree of freedom systems using 20 ground motion data recorded on rock site. The variation of the control performance of frictional damping system is investigated in terms of the dynamic load and the structural natural period, of which effects were not considered in the previous studies. Least square curve fitting equations are presented for describing those normalized response spectrum and optimal non-dimensional friction forces are obtained for controlling the peak displacement and absolute acceleration of the structure based on the derivative of the curve-fitted design spectrum.