• Title, Summary, Keyword: harmonic loading

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Vibration Reaponse Analysis of frames with energy absober installed in Beams (보 제진 프레임의 진동응답해석)

  • Lee, Ho
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.159-166
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    • 1997
  • The purpose of this thesis is to derive a theoretical model of the hysteretic resistance of the visco-elastic damper based on test results of harmonic excitation and to investigate of the basis of theory and experiment the effect of vibration control and response characteristics of portal frames degree vibration systems provided with the damper. The behaviour of a visco-elastic degree under dynamic loading is idealized by a model of the theory of visco-elasticity, i.e. a four-parameter model formed as a parallel combination of Maxwell fluid and Kelvin-Voigh models and its constitutive equation is derived. The model parameters are determined for a tested damper from the datas of harmonic excitation tests. The theoretical model of the damper is incorporated in equation fo motion of single degree of freedom. A computer program for solving the equation is written using Runge-kuttas's numerical integration scheme. Using this analysis program test cases of the earthquake excitation are simulated and the results of the simulation are the results of the simulation are the results of the simulation are compared with the test results.

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Sound Radiation From Infinite Beams Under the Action of Harmonic Point Forces (조화집중하중을 받는 무한보에서의 음향방사)

  • 김병삼;홍동표
    • Journal of KSNVE
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    • v.2 no.1
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    • pp.33-39
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    • 1992
  • The problem of sound radiation from infinite elastic beams under the action of harmonic point forces is studied. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z = 0 and to be axially infinite. The beam material and the elastic foundation re assumed to be lossless and Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation $(\kappa_s)$ will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results are examined as a function of wavenumber ratio$(\gamma)$ and stiffness factor$(\Psi)$. Here, our purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.

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Sound Radiation From Infinite Beams Under the Action of Harmonic Moving Line Forces (조화분포이동하중을 받는 무한보에서의 음향방사)

  • 김병삼;이태근;홍동표
    • Journal of KSNVE
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    • v.3 no.3
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    • pp.245-251
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    • 1993
  • The problem of sound radiation from infinite elastic beams under the action on harmonic moving line forces is studies. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z=0 and to be axially infinite. The beam material and elastic foundation are assumed to be lossless and Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation $(\kappa_s)$ will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results examined as a function of Mach number (M), wavenumber ratio$(\gamma{)}$ and stiffness factor $(\Psi{)}$. Here, our purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.

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Sound radiation of curved beam under the action of harmonic line forces (조화분포하중을 받는 원환보의 음향방사)

  • 지창헌
    • Journal of the Korean Society of Safety
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    • v.12 no.3
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    • pp.10-16
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    • 1997
  • The problem of sound radiation from curved beam under the action of harmonic line forces is studied. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y=0. The curved beam material and the elastic foundation are assumed to be lossless including a tension force(T), damping coefficient(C) and stiffness of foundation($k_s$) will be employed. The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire curved beam. The expression for sound power is integrated numerically and the results are examined as a function of wavenumber ratio($\gamma$) and stiffness factor($\psi$).

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An Improved Control Approach for DSTATCOM with Distorted and Unbalanced AC Mains

  • Singh, Bhim;Solanki, Jitendra
    • Journal of Power Electronics
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    • v.8 no.2
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    • pp.131-140
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    • 2008
  • This paper presents a new control approach of DSTATCOM (distribution static compensator) for compensation of reactive power, unbalanced loading and harmonic currents under unbalanced non-sinusoidal ac mains. The control of DSTATCOM is achieved using Adaline based current estimator based on LMS algorithm to maintain source currents real and undistorted. The dc bus voltage of voltage source converter (VSC) working as DSTATCOM is maintained at constant voltage using a proportional-integral (PI) controller. The DSTATCOM system alongwith proposed control scheme is modeled in MATLAB to simulate the behavior of the system. The practical implementation of the DSTATCOM is carried out using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. Simulated and implementation results are presented to demonstrate the effectiveness of the DSTATCOM with Adaline based control to meet the severe load perturbations with different types of loads (linear and non-linear) under distorted and unbalanced AC mains.

Dynamic contact response of a finite beam on a tensionless Pasternak foundation under symmetric and asymmetric loading

  • Coskun, Irfan
    • Structural Engineering and Mechanics
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    • v.34 no.3
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    • pp.319-334
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    • 2010
  • The dynamic response of a finite Bernoulli-Euler beam resting on a tensionless Pasternak foundation and subjected to a concentrated harmonic load is investigated in this study. This load may be applied at the center of the beam, or it may be offset from the center. Since the elastic foundation is assumed to be tensionless, the beam may lift off the foundation, resulting in contact and non-contact regions in the system. An analytical/numerical solution is obtained from the governing equations of the contact and non-contact regions to determine the coordinates of the lift-off points. Although there is no nonlinear term in the equations, the problem appears to be nonlinear since the contact regions are not known in advance. Due to that nonlinearity, the essentials of the problem (the coordinates of the lift-off points) are calculated numerically using the Newton-Raphson technique. The results, which represent the symmetric and asymmetric responses of the beam, are presented graphically in this work. They illustrate the effects of the forcing frequency and the beam length on the extent of the contact regions and displacements.

Effect of sweep angle on bifurcation analysis of a wing containing cubic nonlinearity

  • Irani, Saied;Amoozgar, Mohammadreza;Sarrafzadeh, Hamid
    • Advances in aircraft and spacecraft science
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    • v.3 no.4
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    • pp.447-470
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    • 2016
  • Limit cycle oscillations (LCO) as well as nonlinear aeroelastic analysis of a swept aircraft wing with cubic restoring moments in the pitch degree of freedom is investigated. The unsteady aerodynamic loading applied on the wing is modeled by using the strip theory. The harmonic balance method is used to calculate the LCO frequency and amplitude for the swept wing. Finally the super and subcritical Hopf bifurcation diagrams are plotted. It is concluded that the type of bifurcation and turning point location is sensitive to the system parameters such as wing geometry and sweep angle.

Development of the Helicopter Noise Prediction Code and its Applications (헬리콥터 소음 예측 코드 개발 및 적용사례)

  • Wie, Seong-Yong;Kim, Do-Hyung;Kang, Hee Jung;Chung, Ki-Hoon;Hwang, Changjeon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.904-910
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    • 2014
  • The Helicopter noise analysis code was developed using Farassat's Formular 1A based on Ffowcs-Williams and Hawkings equation and Lowson's Formula which contains single loading noise source concept. HART-II(Higher harmonic control Aeroacoustic Rotor Test), STAR(Smart-Twisting Active Rotor) and Active-tab Rotor were computed and analyzed by using developed noise code. The results of these rotor noise prediction are explained and its applicability would be mentioned in this paper.

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Analysis of the Magnetic Noise for Large Power Induction Motors at Loading Operation (대용량 유도전동기의 부하 운전 시 자기 소음 특성 해석)

  • Hong, Gil-Dong;Chun, Tae-Won;Lee, Hong-Hee;Kim, Heung-Gun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.3
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    • pp.509-515
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    • 2009
  • When a squirrel cage induction motor is loaded, the magnetic noise can increase depending on the load current. It is due to the variation of air gap harmonic fluxes from the rotor current induced by loading. This unfavorable noise can be anticipated by analysing the radial force waves in the air gap, the mode shapes of them, and stator core natural frequencies at each mode. With the experimental tests with the different rotor slot numbers, the variation of magnetic noise depending on the load current is studied and the method to reduce the magnetic noise is suggested with the newly developed magnetic noise analysis program.

Vibration, buckling and dynamic stability of a cantilever rectangular plate subjected to in-plane force

  • Takahashi, Kazuo;Wu, Mincharn;Nakazawa, Satoshi
    • Structural Engineering and Mechanics
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    • v.6 no.8
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    • pp.939-953
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    • 1998
  • Vibration, buckling and dynamic stability of a cantilever rectangular plate subjected to an in-plane sinusoidally varying load applied along the free end are analyzed. The thin plate small deflection theory is used. The Rayleigh-Ritz method is employed to solve vibration and buckling of the plate. The dynamic stability problem is solved by using the Hamilton principle to drive time variables. The resulting time variables are solved by the harmonic balance method. Buckling properties and natural frequencies of the plate are shown at first. Unstable regions are presented for various loading conditions. Simple parametric resonances and combination resonances with sum type are obtained for various loading conditions, static load and damping.