scholarly journals Study of Magnetic Vibration Absorber with Permanent Magnets along Vibrating Beam Structure

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
F. B. Sayyad ◽  
N. D. Gadhave
Keyword(s):  
Cantilever Beam ◽  
Gas Turbines ◽  
Permanent Magnets ◽  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Vibration Absorber ◽  
Primary System ◽  
Vibration Absorbers ◽  
Vibratory System ◽  
Electrical Generator

The vibration absorbers are frequently used to control and minimize excess vibration in structural system. Dynamic vibration absorbers are used to reduce the undesirable vibration in many applications such as pumps, gas turbines, engine, bridge, and electrical generator. To reduce the vibration of the system, the frequency of absorber should be equal to the excitation frequency. The aim of this study is to investigate the effect of magnetic vibration absorber along vibrating cantilever beam. This study will aim to develop a position of magnetic vibration absorber along the cantilever beam to adopt the change in vibratory system. The absorber system is mounted on a cantilever beam acting as the primary system. The objective is to suppress the vibration of the primary system subjected to a harmonic excitation whose frequencies are varying. It can be achieved by varying the position of magnetic vibration absorber along the length of beam. The advantage of magnetic vibration absorber is that it can be easily tuned to the excitation frequency, so it can be used to reduce the vibration of system subjected to variable excitation frequency.

scholarly journals Active Vibration Absorber for a Continuous Structure Model

2021 ◽  
Author(s):  
Carlos Gianpaul Rincón ◽  
Jorge Alencastre ◽  
Richard Rivera
Keyword(s):  
Cantilever Beam ◽  
Excitation Frequency ◽  
Element Model ◽  
Continuous Model ◽  
Dynamical Behaviour ◽  
Electrical Circuit ◽  
Vibration Absorber ◽  
Piping System ◽  
Primary System ◽  
Active Vibration

The reduction of mechanical vibrations is field of continuous research in engineering in order to reduce damage and improve the performance of structures, machinery, piping and others systems, when they are in presence of dynamical forces. In this sense, different alternatives have been proposed over time, the active vibration absorber highlights as an alternative which can absorb the vibration from a primary system for different excitation frequency in real time. In this study, an active vibration absorber has been modelled as an electromechanical device composed of a 1-DOF model for the absorber and an equivalent electrical circuit for the electromagnetic actuator. It was implemented in a real structure represented by a cantilever beam continuous model, which is the most accurate model that can be used. A set of differential equations which represent the dynamical behaviour of the cantilever beam implemented with the active vibration absorber was obtained from the complete model and it was simulated in Matlab Simulink®. An application of the active vibration absorber for an industry piping system based on the finite element model formulation is presented and developed. Results indicate that the active vibration absorber is able to significantly reduce the vibrations amplitude of the primary system, especially in resonance conditions, for a discrete frequency range. The analytic model and procedure developed here can easily widespread to any more complex primary system.

Optimum design for a novel inerter-based vibration absorber with an amplified inertance and grounded stiffness for enhanced vibration control

2021 ◽  
pp. 107754632110132
Author(s):  
Marcial Baduidana ◽  
Aurelien Kenfack-Jiotsa
Keyword(s):  
Primary Structure ◽  
Fixed Point Theory ◽  
Damping Ratio ◽  
Time History ◽  
Harmonic Excitation ◽  
Vibration Absorber ◽  
Primary System ◽  
Vibration Absorbers ◽  
Stiffness Ratio ◽  
Optimum Frequency

This article presents the results of the study of a novel inerter-based vibration absorber with an amplified inertance mechanism and grounded stiffness, to control excessive vibrational movements of an excited primary structure. The inerter vibration absorber used in this study acts as a passive tuned inerter damper. An undamped primary structure model with a single degree of freedom controlled by the proposed inerter vibration absorber is developed and used to derive the equations of motion of the coupled system. The optimum frequency ratio and the optimum damping ratio of inerter vibration absorber are found using the fixed point theory for harmonic force-excited primary structures. Then, the optimum grounded stiffness ratio is deduced. Based on the inclusion of an amplified inertance mechanism, it is found that for given inertance mass ratio, the change in the amplification ratio results in three cases for the optimum grounded stiffness ratio, that is, negative, zero, and positive. From these three cases of grounded stiffness, the inerter vibration absorber with positive grounded stiffness has demonstrated the best control performance. Under optimum parameters, the results indicate that the inerter vibration absorber in this article outperforms some existing inerter vibration absorbers under the harmonic excitation, in terms of decreases in the peak vibration response of the primary system and widens the suppression bandwidth. Finally, the further comparison among the inerter vibration absorber under random (white noise) excitation also shows that the model in this article is superior to other inerter vibration absorbers in terms of smallest mean square response and smallest variance of the time history of the primary system.

Using a Vibration Absorber to Suppress Chatter Vibration in Turning Process With a Worn Tool

2009 ◽  
Author(s):  
Hamed Moradi ◽  
Firooz Bakhtiari-Nejad ◽  
Mohammad R. Movahhedi
Keyword(s):  
Transmission Lines ◽  
Gas Turbines ◽  
Block Diagram ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Turning Process ◽  
Electrical Transmission ◽  
Chatter Suppression ◽  
Orthogonal Turning ◽  
Dynamic Vibration Absorbers

Dynamic vibration absorbers are used as semi-active controllers to reduce the undesirable vibrations in many applications such as electrical transmission lines, helicopters, gas turbines, engines, bridges and etc. One type of these absorbers is tunable vibration absorber (TVA). In this paper, regenerative chatter in an orthogonal turning process is suppressed using a (TVA). It is shown that TVA can modify the frequency response function of the cutting tool so as to improve cutting stability in turning process. In addition, tool wear is an important factor which works as a positive damping and helps the chatter suppression beside exertion of the TVA. Finally, using the SIMULINK Toolbox of MATLAB, the analog simulated block diagram of the problem is developed. The advantage of this simulation is that, one can analyze the effect of other types of excitations such as step, ramp, etc on the absorbed system.

Passive/Active Autoparametric Cantilever Beam Absorber With Piezoelectric Actuator for a Two-Story Building-Like Structure

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Gerardo Silva-Navarro ◽  
Hugo F. Abundis-Fong
Keyword(s):  
Cantilever Beam ◽  
Active Vibration Control ◽  
Parametric Uncertainty ◽  
Vibration Absorber ◽  
Primary System ◽  
Internal Resonances ◽  
Piezoelectric Patch ◽  
Active Vibration ◽  
Stiffness And Damping ◽  
Story Building

This work deals with the design and experimental evaluation of a passive/active cantilever beam autoparametric vibration absorber mounted on a two-story building-like structure (primary system), with two rigid floors connected by flexible columns. The autoparametric vibration absorber consists of a cantilever beam with a piezoelectric patch actuator, cemented to its base, mounted on the top of the structure and actively controlled through an acquisition system. The overall system is then a coupled nonlinear oscillator subjected to sinusoidal excitation in the neighborhood of its external and internal resonances. The addition of the piezoelectric patch actuator to the cantilever beam absorber makes active the passive vibration absorber, thus enabling the possibility to control its equivalent stiffness and damping and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies and parametric uncertainty.

Parameters optimization of dynamic vibration absorber based on grounded stiffness, inerter, and amplifying mechanism

2021 ◽  
pp. 107754632110382
Author(s):  
Peng Sui ◽  
Yongjun Shen ◽  
Shaopu Yang ◽  
Junfeng Wang
Keyword(s):  
Analytical Solution ◽  
Vibration Isolation ◽  
Damping Ratio ◽  
Vibration Absorber ◽  
Primary System ◽  
Vibration Absorbers ◽  
Stiffness Ratio ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Dynamic Vibration Absorbers

In the field of dynamics and control, some typical vibration devices, including grounded stiffness, inerter and amplifying mechanism, have good vibration isolation and reduction effects, especially in dynamic vibration absorber (DVA). However, most of the current research studies only focus on the performance of a single device on the system, and those DVAs are gradually becoming difficult to meet the growth of performance demand for vibration control. On the basis of Voigt dynamic vibration absorber, a novel dynamic vibration absorber model based on the combined structure of grounded stiffness, inerter, and amplifying mechanism is presented, and the analytical solution of the optimal design formula is derived. First, the motion differential equation of the system is established, and the normalized amplitude amplification factor of the displacement is calculated. It is found that the system has three fixed points unrelated to the damping ratio. The optimal frequency ratio is obtained based on the fixed-point theory. In order to ensure the stability of the system, it is found that inappropriate inerter coefficient will cause the system instable when screening optimal grounded stiffness ratio. Accordingly, the best working range of inerter is determined. Finally, optimal grounded stiffness ratio and approximate optimal damping ratio are also obtained. The influence of inerter coefficient and magnification ratio on the response of the primary system is analyzed. The correctness of the derived analytical solution is verified by numerical simulation. Compared with other dynamic vibration absorbers, it is verified that presented model has superior vibration absorption performance and provides a theoretical basis for the design of a new type of dynamic vibration absorbers.

Tunable Active Vibration Absorber: The Delayed Resonator

1995 ◽  
Vol 117 (4) ◽  
pp. 513-519 ◽  
Author(s):  
Nejat Olgac ◽  
Brian Holm-Hansen
Keyword(s):  
Transient Absorption ◽  
A Priori ◽  
Excitation Frequency ◽  
Vibration Absorber ◽  
Primary System ◽  
Active Vibration ◽  
Absorption Performance ◽  
Primary Focus ◽  
Novel Concept ◽  
Stability Issues

This paper elaborates upon a novel concept, the Delayed Resonator, a tunable active vibration absorber. This technique uses a control which has a time delayed feedback of the absorber mass displacement. The substance of this process is in that the absorber completely removes oscillations from the primary structure. Two very strong features that should be mentioned are: (a) the excitation frequency range can vary over a semi-infinite interval, and (b) the absorber can be tuned in real time. These are the unique characteristics of the technique distinguishing it from the others. Stability issues of the primary system combined with the Delayed Resonator are addressed following Nyquist and root locus methods. In particular, the absorption performance for cases with time varying excitation frequency is studied. The primary focus of this paper is on the analysis of transient absorption behavior of the Delayed Resonator during its tuning. An example case is provided which considers a step change in the excitation frequency. A well-pronounced manifestation of the tunability feature of the Delayed Resonator is observed. The superiority of the Delayed Resonator absorber over the conventional a priori tuned absorbers is also demonstrated.

Modal Overlap and Dissipation Effects of a Cantilever Beam with Multiple Attached Oscillators

2000 ◽  
Vol 123 (2) ◽  
pp. 181-187 ◽  
Author(s):  
M. V. Drexel ◽  
J. H. Ginsberg
Keyword(s):  
Transfer Function ◽  
Natural Frequency ◽  
Cantilever Beam ◽  
Impulse Response ◽  
Critical Issue ◽  
Harmonic Excitation ◽  
Vibration Absorber ◽  
Continuous Systems ◽  
Coupled Equations ◽  
Eigenmode Analysis

This work was prompted by a study performed by Strasberg [7] in which numerous small spring-mass-damper systems are attached to a large suspended mass representing the master structure. The isolated natural frequency of each attached system was selected to match in average the natural frequency of the isolated master structure. Strasberg found that the critical issue when an impulse excitation is applied to the master structure is the bandwidth of the isolated attached systems in comparison to the spacing between the natural frequencies of the system. Modal overlap, which corresponds to bandwidths that exceed the spacing of those frequencies, was shown to greatly influence the response of the master structure. Light damping, for which there is little or no modal overlap, corresponds to an impulse response that consists of a sequence of nearly periodic exponentially decaying pulses, and the transfer function for harmonic excitation of the master structure indicates that the substructure acts as a vibration absorber for the master structure. Increased damping leads to modal overlap, with the result that the impulse response consists of a single decaying pulse. The frequency domain transfer function indicates that the vibration absorber effect is enhanced. The present work explores these issues for continuous systems by replacing the one degree of freedom master structure with a cantilever beam. The system parameters are selected to match Strasberg’s model, with the suspended oscillators placed randomly along the beam. The beam displacement is represented as a Ritz series whose basis functions are the cantilever beam modes. The coupled equations are solved by a state-space eigenmode analysis that yields a closed form representation of the response in terms of the complex eigenmode properties. The continuous fuzzy structure is shown not to display the transfer of energy between the master structure and the substructure that was exhibited by the discrete fuzzy structure, apparently because of the asynchronous motion of the attachment points resulting from the spatial variability of the beam’s motion. The vibration absorber effect for harmonic excitation is only obtained for the heavy damping in the case of a beam.

A Tunable Vibration Absorber Design to Suppress Chatter in Boring Manufacturing Process

2007 ◽  
Author(s):  
H. Moradi ◽  
F. Bakhtiari-Nejad ◽  
M. R. Movahhedi
Keyword(s):  
Transmission Lines ◽  
Gas Turbines ◽  
Block Diagram ◽  
Summation Method ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Electrical Transmission ◽  
Dynamic Vibration Absorbers ◽  
Euler Bernoulli Beam ◽  
Mode Summation Method

Dynamic vibration absorbers are used to reduce the undesirable vibrations in many applications such as electrical transmission lines, helicopters, gas turbines, engines, bridges and etc. One type of these absorbers is tunable vibration absorber (TVA) which can act as a semi-active controller. In this paper, by applying a (TVA), chatter vibration is suppressed during boring process in which boring bar is modeled as a cantilever Euler-Bernoulli beam. The optimum specifications of absorber such as spring stiffness, absorber mass and its position can be determined by developing an algorithm based upon mode summation method. Finally, using the SIMULINK Toolbox of MATLAB, the analog simulated block diagram of the problem is developed. The advantage of this simulation is that, one can analyze the effect of other types of excitations such as step, ramp, etc on the absorbed system.

Implementation of a Nonlinear Torsional Vibration Absorber for Suppression of Vibrations in Rotating Machinery

2013 ◽  
Author(s):  
Ammaar Bin Tahir ◽  
Oleg Shiryayev ◽  
Nader Vahdati ◽  
Hamad Karki
Keyword(s):  
Nonlinear Vibration ◽  
Torsional Vibration ◽  
Vibration Suppression ◽  
Nonlinear Energy Sink ◽  
Modal Parameters ◽  
Vibration Absorber ◽  
Primary System ◽  
Vibration Absorbers ◽  
Modal Model ◽  
Linear Spring

Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is tuned for a specific resonant frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies. Vibrations dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. Experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, we carry out the design optimization of the nonlinear torsional vibration absorber using an equivalent 2-DOF modal model. A linear vibration absorber is developed in parallel. Subsequently, both absorbers will be manufactured, assembled and mounted on the system to evaluate their vibration suppression capabilities.

Bifurcation Phenomena Caused by Multiple Nonlinear Vibration Absorbers

2010 ◽  
Vol 5 (2) ◽  
Author(s):  
Takashi Ikeda
Keyword(s):  
Steady State ◽  
Nonlinear Vibration ◽  
Excitation Frequency ◽  
Pitchfork Bifurcation ◽  
Harmonic Excitation ◽  
Vibration Absorbers ◽  
Response Curves ◽  
System Parameters ◽  
Chaotic Vibrations ◽  
Steady State Solutions

The characteristics of two, three, and four nonlinear vibration absorbers or nonlinear tuned mass dampers (NTMDs) attached to a structure under harmonic excitation are investigated. The frequency response curves are theoretically determined using van der Pol’s method. When the parameters of the absorbers are equal, it is found from the theoretical analysis that pitchfork bifurcations may occur on the part of the response curves, which are unstable in the multi-absorber systems, but are stable in a system with one NTMD. Multivalued steady-state solutions, such as three steady-state solutions for a dual-absorber system with different amplitudes, five steady-state solutions for a triple-absorber system, and seven steady-state solutions for a quadruple-absorber system, appear near bifurcation points. The NTMDs behave in that one of them vibrates at high amplitudes while the others vibrate at low amplitudes, even if the dimensions of the NTMDs are identical. Namely, “localization phenomenon” or “mode localization” occurs. After the pitchfork bifurcation, Hopf bifurcations may occur depending on the values of the system parameters, and amplitude- and phase-modulated motions, including chaotic vibrations, appear after the Hopf bifurcation when the excitation frequency decreases. Lyapunov exponents are numerically calculated to prove the occurrence of chaotic vibrations. Bifurcation sets are also calculated to investigate the influence of the system parameters on the response of the systems.

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