Experimental Vibration Control of a Two-Degree of Freedom, State-Switched Absorber System

2002 ◽  
Author(s):  
Mark H. Holdhusen ◽  
Kenneth A. Cunefare
Keyword(s):  
Vibration Control ◽  
Vibration Suppression ◽  
Effective Bandwidth ◽  
Vibration Absorbers ◽  
Lumped Mass ◽  
Tuned Vibration Absorbers ◽  
Resonance Frequencies ◽  
Magneto Rheological ◽  
Theoretical Simulations ◽  
Two Degree Of Freedom

A State-Switched Absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers for vibration control. Previous theoretical simulations show that for a system subjected to a multi-harmonic disturbance, using an appropriate logic for switching states, the SSA reduces vibration more effectively than classical tuned vibration absorbers (TVA). This paper considers the experimental performance of the SSA for vibration suppression of an elastically mounted lumped mass base. State switching is achieved using magneto-rheological fluid to connect or disconnect a coil spring in parallel with other coil springs. The stiffness state is controlled by applying or removing a magnetic field across of the MR fluid. Experiments were performed over a range of forcing and tuning frequencies. The SSA system, optimally tuned, outperformed the optimal classical TVA system for all combinations of forcing frequencies.

Experimental Validation of a State-Switched Absorber Used to Control Vibrating Continuous Systems

2005 ◽  
Author(s):  
Mark Holdhusen ◽  
Kenneth A. Cunefare
Keyword(s):  
Experimental Validation ◽  
Frequency Component ◽  
Effective Bandwidth ◽  
Continuous Systems ◽  
Vibration Absorbers ◽  
Numerical Work ◽  
Tuned Vibration Absorbers ◽  
Resonance Frequencies ◽  
Magneto Rheological ◽  
The Magnetic Field

A state-switched absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers for vibration control. Previous numerical work has shown that an optimized SSA outperforms an optimized TVA at controlling vibrations of both a beam and a plate. This paper details the experimental validation of these simulation results. An SSA was realized by employing magneto-rheological elastomers to achieve a stiffness change. The stiffness of these elastomers is a function of the magnetic field put across them. Experiments were conducted on both a cantilever beam and a square plate clamped on all sides. Each system was excited by several two-frequency component excitations. For each forcing combination, several tuning configurations of the SSA were applied and the kinetic energy of the system was found. This observed performance was compared to the performance found through numerical simulations of a system with a similar tuning and excitation configuration. It was found that the observed performance follows closely with results found through numerical simulation.

Implementation of Tuned Vibration Absorbers for Above Ground Pipeline Vibration Control

2000 ◽  
Author(s):  
Mark A. Norris ◽  
Keith R. Ptak ◽  
Ben A. Zamora ◽  
James D. Hart
Keyword(s):  
Vibration Control ◽  
Vibration Suppression ◽  
The Arctic ◽  
Vibration Absorbers ◽  
Recent Application ◽  
Optimal Tuning ◽  
Tuned Vibration Absorbers ◽  
Recent Developments ◽  
Environmental Considerations ◽  
Pipeline Vibration

An overview of recent developments of tuned vibration absorbers (TVAs) for vibration suppression is presented. The paper summarizes some popular theory for analysis and optimal tuning of these devices, discusses various design configurations, and reviews the recent application of TVAs to control wind-induced oscillations of pipelines above the Arctic Circle. Although the wind-induced pipeline vibrations are relatively small, the accumulation of vibration cycles can cause fatigue at pipeline joints. The TVAs used in this application have reduced the RMS displacements of the pipeline by as much as a factor of seven. Additionally, the paper introduces a new overhead TVA installation on the pipeline for accommodating environmental considerations.

Experimental Dynamic Analysis of Magneto-Rheological Tuned Vibration Absorbers

2003 ◽  
Author(s):  
Jeong-Hoi Koo ◽  
Mehdi Ahmadian ◽  
Mehdi Setareh ◽  
Thomas M. Murray
Keyword(s):  
Active Control ◽  
Primary Structure ◽  
Control Policy ◽  
Vibration Absorbers ◽  
Control Policies ◽  
Output Displacement ◽  
Tuned Vibration Absorbers ◽  
Control Schemes ◽  
Displacement Based ◽  
Magneto Rheological

The primary purpose of this study is to experimentally evaluate the dynamics of a Magneto-Rheological Tuned Vibration Absorber (MR TVA) with several semi-active control schemes. A test rig was built to represent a two-degree of freedom primary structure model coupled with an MR TVA, and four semi-active control policies were considered. The four control policies include: velocity-based, on-off groundhook control (on-off VBG); velocity-based, continuous groundhook control (continuous VBG); displacement-based, on-off groundhook control (on-off DBG); and displacement-based, continuous groundhook control (continuous DBG). Using the test apparatus, a series of tests were conducted to investigate the dynamics of the MR TVA with each control policy. The performances of each of the cases were then analyzed along with the equivalent passive TVA. The performance index was the transmissibility between the input and the output displacement of the structure. The experimental results indicated that the MR TVA with all of the semi-active control policies, outperformed the passive TVA in reducing structural vibrations. Furthermore, the displacement-based groundhook control policies perform better in reducing the resonant vibrations of the primary structure than the velocity-based groundhook control schemes.

Synthesis and Experimental Validation of a Delayed Reference Controller for Active Vibration Suppression in Mechanical Systems

2004 ◽  
Vol 72 (4) ◽  
pp. 623-627 ◽  
Author(s):  
P. Gallina ◽  
A. Trevisani
Keyword(s):  
Time Delay ◽  
Vibration Control ◽  
Experimental Validation ◽  
Vibration Suppression ◽  
Overhead Cranes ◽  
Simple Pendulum ◽  
Active Vibration Suppression ◽  
Control Scheme ◽  
Active Vibration ◽  
Two Degree Of Freedom

This paper introduces a non-time-based control scheme for active position and vibration control of two-degree-of-freedom systems by applying it to the path-tracking and swing control of a system composed of a trolley and a simple pendulum. The basic idea behind such a scheme is to make the path reference of the trolley a function of the time and of a time delay. This latter, which is affected by the measured oscillation, is calculated on-the-fly in order to reduce the swing phenomenon. The effectiveness of the proposed control scheme, which may have application to the control of overhead cranes, is proved experimentally.

scholarly journals Some Recent Developments in Adaptive Tuned Vibration Absorbers/Neutralisers

2006 ◽  
Vol 13 (4-5) ◽  
pp. 531-543 ◽  
Author(s):  
Michael J. Brennan
Keyword(s):  
Vibration Control ◽  
Narrow Band ◽  
Notch Filter ◽  
Variable Stiffness ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
The Past ◽  
Tuned Vibration Absorbers ◽  
Control Scheme ◽  
Recent Developments

The vibration absorber has been used for vibration control purposes in many sectors of engineering from aerospace, to automotive to civil, for the past 100 years or so. A limitation of the device, however, is that it acts like a notch filter, only being effective over a narrow band of frequencies. Recent developments have overcome this limitation by making it possible to tune the device over a range of frequencies. This has been achieved by incorporating a variable stiffness element that can be adjusted in real-time. In this paper, some ways in which stiffness change can be achieved in practice are reviewed and some examples of prototype adaptive tuned vibration absorbers (ATVAs) are described. A simple control scheme to automatically tune an ATVA is also presented.

State-Switched Absorber for Vibration Control of Point-Excited Beams

2000 ◽  
Author(s):  
Kenneth A. Cunefare
Keyword(s):  
Dynamical System ◽  
Vibration Control ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Spring Element ◽  
Current State ◽  
Resonance Frequencies ◽  
Spectral Components ◽  
Improved Performance ◽  
Force Excitation

Abstract A system that has the capability to make instantaneous changes in its mass, stiffness, or damping may be termed a state-switchable dynamical system. Such a system will display different dynamical responses dependent upon its current state. State-switchable stiffness may be practically obtained through the control of the termination impedance of piezoelectric stiffness elements. If such a switchable stiffness element is incorporated as part of the spring element of a vibration absorber, the change in stiffness causes a change in the resonance frequencies of the system, thereby instantaneously ‘retuning’ the state-switched absorber to a new frequency. In between state switches, the operation of such a device is passive, being fundamentally a passive vibration absorber. This concept has improved performance over classical passive vibration absorbers or dampers, particularly for disturbances with multiple spectral components. This paper considers the application of such a device for the purpose of vibration control on beams subjected to harmonic point-force excitation.

A Study on the Application of Tuned Vibration Absorbers to Nominally Cyclic Structures

2019 ◽  
Author(s):  
Mainak Mitra ◽  
Andrea Lupini ◽  
Bogdan I. Epureanu
Keyword(s):  
Small Mass ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Lumped Mass ◽  
Absorption Mechanism ◽  
Vibration Absorption ◽  
Tuned Vibration Absorbers ◽  
Cyclic Symmetric ◽  
Stiffness And Damping ◽  
Symmetric Structures

Abstract The vibration absorber or tuned mass damper is a well-known mechanism, where a small mass connected to a larger structure is used to redirect vibration energy and provide reduction in vibration amplitudes at desired locations and frequencies. While tuned vibration absorbers have been widely applied for damping of mechanical systems, the concept remains largely unexplored in the design of dampers for bladed disks. This paper investigates whether such a vibration absorption mechanism is feasible for such nominally cyclic symmetric structures which are characterized by double modes, high modal density, and sensitivity to uncertainties such as mistuning. The single-degree of freedom vibration absorber concept is extended for application to this complex modal space, and lumped mass models are used for analysis. Trends in effectiveness of a vibration absorption based damper are explored by studying sensitivities to various parameters such as stiffness and damping at various locations. Effects of mistuning across sectors and locations of damper attachment are also considered. The results of the study establish the feasibility of the vibration absorption mechanism for application in blisks, and encourage further exploration of the concept, possibly in conjunction with other well-established damping mechanisms such as friction.

Study on Machining Vibration Suppression with Multiple Tuned Mass Dampers: Vibration Control for Long Fin Machining

2017 ◽  
Vol 11 (2) ◽  
pp. 206-214 ◽  
Author(s):  
Ippei Kono ◽  
◽  
Takayuki Miyamoto ◽  
Koji Utsumi ◽  
Kenji Nishikawa ◽  
...  
Keyword(s):  
Vibration Control ◽  
Vibration Suppression ◽  
Dynamic Stiffness ◽  
System Model ◽  
End Mill ◽  
Lumped Mass ◽  
Tuned Mass Dampers ◽  
Machining Test ◽  
Low Stiffness ◽  
Multiple Tuned Mass Dampers

This study aims to suppress vibration during the machining of long and thin fin parts. Typically, fin parts have low stiffness because fixing the fin is impeded by a end-mill, machine tool or other fins. In this study, multiple tuned mass dampers (TMDs) with the same characteristics were applied to the machining of a fin part measuring 18 mm × 180 mm × 2600 mm. The characteristics of the TMDs were optimized by calculation using a lumped-mass-points system model of the fin part. Then, an impact hammer test and a machining test were conducted on the actual fin part. The dynamic stiffness of the fin part was improved by up to 14 times by using five TMDs, and the amplitude of vibration during machining was decreased by more than 90%.

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