• Title/Summary/Keyword: Primary Vibration System

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Active Noise Control in a Duct System Using the Hybrid Control Algorithm (하이브리드 제어 알고리즘을 이용한 덕트내 능동소음제어)

  • Lee, You-Yub;Park, Sang-Gil;Oh, Jae-Eung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.3
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    • pp.288-293
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    • 2009
  • This study presents the active noise control of duct noise. The duct was excited by a steady-state harmonic and white noise force and the control was performed by one control speaker attached to surface of the duct. An adaptive controller based on filtered x LMS(FXLMS) algorithm was used and controller was defined by minimizing the square of the response of the error microphone. The assemble controller, which is called a hybrid ANC(active noise control) system, was combined with feedforward and feedback controller. The feedforward ANC attenuates primary noise that is correlated with the reference signal, while the feedback ANC cancels the narrowband components of the primary noise that are not observed by the reference sensor. Furthermore, in many ANC applications, the periodic components of noise are the most intense and the feedback ANC system has the effect of reducing the spectral peaks of the primary noise, thus easing the burden of the feedforward ANC filter.

Global Bifurcations and Chaos Via Breaking of KAM Tori of an Harmonically Excited Imperfect Circular Plate

  • Samoylenko, S.B.;Lee, W.K.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.419-422
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    • 2005
  • Global bifurcations and chaos in modal interactions of an imperfect circular plate with one-to-one internal resonance are investigated. The case of primary resonance, in which an excitation frequency is near natural frequencies, is considered. The damping force is not included in the analysis. The renormalization-group technique for KAM tori is used to obtain the criteria for large-scale stochasticity in the system.

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Damping Characteristics of Impact Damper (충격식 감쇠기의 감쇠특성에 관한 연구)

  • 김원철;전순기;양보석;문덕호
    • Journal of KSNVE
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    • v.3 no.1
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    • pp.29-37
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    • 1993
  • This study is concerned about the impact type damper for effectively restraining the high vibration amplitude in the resonance regions. The theoretical analysis is based on the assumption that the impacts occur twice per cycle at an equal time interval. Simple but reasonable approximations have been derived for the optimum collision clearance and maximum amplitude ratio. Using the impact dampers which is rigidly attached to the primary vibration system, we have experimented for mass ratios and restitution coefficients. The experimental results are in good agreement with theoretical results.

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Global Bifurcations and Chaos in an Harmonically Excited and Undamped Circular Plate

  • Samoylenko, Sergey B.;Lee, Won-Kyoung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.140-144
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    • 2004
  • Global bifurcations and chaos in modal interactions of an imperfect circular plate with one-to-one internal resonance are investigated. The case of primary resonance, in which an excitation frequency is near natural frequencies, is considered. The damping force is not included in the analysis. The Melnikov's method for heteroclinic orbits of the autonomous system was used to obtain the criteria for chaotic motion.

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Expriment of the Vertical Vibration for Effect of the Parameter of Stiffness Ratio of the Small Scale Passenger Vehicle (여객차량 현가장치의 강성비 변화에 의한 진동 실험)

  • 최경진;장동욱;권영필;김완두
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.1110-1115
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    • 2002
  • The purpose of this study is to analyze the effects of the parameters of the suspension system in railway rolling-stock for KT-23 type passenger vehicle. According to the results of simulation and the small scale vehicle test. Optimal condition was obtained for the stiffness ratio of the primary spring and secondary spring of the suspension system. When the stiffness ratio was Increased, the vortical vibration was increased on the car body for empty and weight car. The result of this study are stable to use of the optimum parameter of the ride duality of KT-23 type vehicle. Also, it is usefull to development of full scale vehicle dynamomer

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A Study on the Vibration Phenomena of the Duct-fan Systems in Fossil Fueled Boilers : Inlet Vortex Induced Excessive Vibration (화력 발전용 보일러 덕트-홴 시스템의 진동현상에 대한 연구 : 입구측 와류에 의한 과대진동 사례)

  • 김철홍;주영호
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.3
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    • pp.194-201
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    • 2003
  • During the operation, fatigue failures and cracks of duct plate due to excessive duct vibration occurred in a fan-duct system of fossil fueled boilers. We measured static pressure variation (pressure pulsation) in the outlet, and also measured vibration at the outlet duct of a centrifugal fan. It was found that strong pressure pulsation caused by the inlet vortex occurred in inlet vane of centrifugal fan in the middle range of vane opening. Thus, excessive duct vibration is caused by strong pressure pulsation. In this Paper, it is shown that the frequency and amplitude of pressure pulsation depend mainly on vane opening and are compared with duct vibration. Also, effective solution for reducing pressure pulsation and vibration are presented.

Research on vibration control of a transmission tower-line system using SMA-BTMD subjected to wind load

  • Tian, Li;Luo, Jingyu;Zhou, Mengyao;Bi, Wenzhe;Liu, Yuping
    • Structural Engineering and Mechanics
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    • v.82 no.5
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    • pp.571-585
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    • 2022
  • As a vital component of power grids, long-span transmission tower-line systems are vulnerable to wind load excitation due to their high flexibility and low structural damping. Therefore, it is essential to reduce wind-induced responses of tower-line coupling systems to ensure their safe and reliable operation. To this end, a shape memory alloy-bidirectional tuned mass damper (SMA-BTMD) is proposed in this study to reduce wind-induced vibrations of long-span transmission tower-line systems. A 1220 m Songhua River long-span transmission system is selected as the primary structure and modeled using ANSYS software. The vibration suppression performance of an optimized SMA-BTMD attached to the transmission tower is evaluated and compared with the effects of a conventional bidirectional tuned mass damper. Furthermore, the impacts of frequency ratios and SMA composition on the vibration reduction performance of the SMA-BTMD are evaluated. The results show that the SMA-BTMD provides superior vibration control of the long-span transmission tower-line system. In addition, changes in frequency ratios and SMA composition have a substantial impact on the vibration suppression effects of the SMA-BTMD. This research can provide a reference for the practical engineering application of the SMA-BTMD developed in this study.

Vibration performance of composite steel-bar truss slab with steel girder

  • Liu, Jiepeng;Cao, Liang;Chen, Y. Frank
    • Steel and Composite Structures
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    • v.30 no.6
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    • pp.577-589
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    • 2019
  • In this study, on-site testing was carried out to investigate the vibration performance of a composite steel-bar truss slab with steel girder system. Ambient vibration was performed to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes). The composite floor possesses low frequency (< 10 Hz) and damping (< 2%). Based on experimental, theoretical, and numerical analyses on natural frequencies and mode shapes, the boundary condition of SCSC (i.e., two opposite edges simply-supported and the other two edges clamped) is deemed more reasonable for the composite floor. Walking excitations by one person (single excitation), two persons (dual excitation), and three persons (triple excitation) were considered to evaluate the vibration serviceability of the composite floor. The measured acceleration results show a satisfactory vibration perceptibility. For design convenience and safety, a crest factor ${\beta}_{rp}$ describing the ratio of peak acceleration to root-mean-square acceleration induced from the walking excitations is proposed. The comparisons of the modal parameters determined by ambient vibration and walking tests reveal the interaction effect between the human excitation and the composite floor.

Estimation of viscous and Coulomb damping from free-vibration data by a least-squares curve-fitting analysis

  • Slemp, Wesley C.H.;Hallauer, William L. Jr.;Kapania, Rakesh K.
    • Smart Structures and Systems
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    • v.4 no.3
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    • pp.279-290
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    • 2008
  • The modeling and parameter estimation of a damped one-degree-of-freedom mass-spring system is examined. This paper presents a method for estimating the system parameters (damping coefficients and natural frequency) from measured free-vibration motion of a system that is modeled to include both subcritical viscous damping and kinetic Coulomb friction. The method applies a commercially available least-squares curve-fitting software function to fit the known solution of the equations of motion to the measured response. The method was tested through numerical simulation, and it was applied to experimental data collected from a laboratory mass-spring apparatus. The mass of this apparatus translates on linear bearings, which are the primary source of light inherent damping. Results indicate that the curve-fitting method is effective and accurate for both perfect and noisy measurements from a lightly damped mass-spring system.

Effect of the Parameter of the Suspension System on the the Vertical Vibration of the Passenger Vehicle (객차의 현가장치 변수가 상하진동에 미치는 영향)

  • Hur, Hyun-Moo;Kwon, Young-Pil;Choi, Kyung-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1309-1316
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    • 2002
  • The purpose of this study is to analyze the effects of the parameters of the suspension system in railway rolling-stock for KT-23 type passenger vehicle. According to the results of simulation and the field test, Optimal condition was obtained for the stiffness ratio of the primary spring and the secondary of the suspension system. When the stiffness ratio was increased, the vibration was increased on the car body and decreased on the bogie, and ride quality are getting worse because of increase of the vertical natural frequency of the car body. The results of this study are usefull to improve the technology of the ride quality of KT-23 type vehicle.