MODAL ANALYSIS OF FLEXIBLE BEAMS WITH DELAYED RESONATOR VIBRATION ABSORBER: THEORY AND EXPERIMENTS

1998 ◽  
Vol 218 (2) ◽  
pp. 307-331 ◽  
Author(s):  
N. Olgac ◽  
N. Jalili
Keyword(s):  
Modal Analysis ◽  
Vibration Absorber ◽  
Flexible Beams ◽  
Resonator Vibration ◽  
Theory And Experiments

The Influence Region Analysis for the Delayed Resonator Vibration Absorber

2001 ◽  
Author(s):  
Giulio Grillo ◽  
Nejat Olgac
Keyword(s):  
Vibration Suppression ◽  
Vibration Absorber ◽  
Primary System ◽  
Frequency Interval ◽  
Vibration Absorption ◽  
Region Analysis ◽  
The Common ◽  
Resonator Vibration ◽  
Three Degree Of Freedom ◽  
Tuned Vibration Absorber

Abstract This paper presents an influence region analysis for an actively tuned vibration absorber, the Delayed Resonator (DR). DR is shown to respond to tonal excitations with time varying frequencies [1–3]. The vibration suppression is most effective at the point of attachment of the absorber to the primary structure. In this study we show that proper feedback control on the absorber can yield successful vibration suppression at points away from this point of attachment. The form and the size of such “influence region” strongly depend on the structural properties of the absorber and the primary system. There are a number of questions addressed in this paper: a) Stability of vibration absorption, considering that a single absorber is used to suppress oscillations at different locations. b) Possible common operating frequency intervals in which the suppression can be switched from one point on the structure to the others. A three-degree-of-freedom system is taken for as example case. One single DR absorber is demonstrated to suppress the oscillations at one of the three masses at a given time. Instead of an “influence region” a set of “influence points” is introduced. An analysis method is presented to find the common frequency interval in which the DR absorber operates at all three influence points.

Grass trimmer hand-arm vibration reduction using multi-axial vibration absorber

2019 ◽  
Vol 50 (8) ◽  
pp. 245-253
Author(s):  
Sushil S Patil
Keyword(s):  
Modal Analysis ◽  
Vibration Reduction ◽  
Experimental Tests ◽  
Experimental Modal Analysis ◽  
Petrol Engine ◽  
Vibration Absorber ◽  
The Novel ◽  
Axial Vibration ◽  
Substantial Level ◽  
Resonance Frequencies

In this investigation, the novel multi-axial vibration absorber is proposed to reduce the handle vibration of petrol engine grass trimmer. The proposed vibration absorber is designed using Dunkerley’s equation and fabricated for testing. The experimental modal analysis of absorber is conducted to find resonance frequencies of the absorber and to validate the results obtained from equations. The experimental tests are carried on grass trimmer with absorber attached near handle location to find effectiveness of absorber in reducing hand-arm vibrations in the x, y and z directions. The result indicated that the total vibration value measured at the handle of grass trimmer is reduced by substantial level with the attachment of multi-axial vibration absorber.

Robust control of the delayed resonator vibration absorber

1999 ◽  
Vol 7 (6) ◽  
pp. 683-691 ◽  
Author(s):  
M.E. Renzulli ◽  
R. Ghosh-Roy ◽  
N. Olgac
Keyword(s):  
Robust Control ◽  
Vibration Absorber ◽  
Resonator Vibration

Optimal Placement of PZT Transducers for Passive Vibration Control of Planar Composite Structures

Aerospace ◽  
2003 ◽  
Author(s):  
Suresh V. Venna ◽  
Y. J. Lin
Keyword(s):  
Finite Element ◽  
Vibration Control ◽  
Modal Analysis ◽  
Electric Potential ◽  
Composite Structures ◽  
Composite Plate ◽  
Optimal Placement ◽  
Vibration Absorber ◽  
Passive Vibration Control ◽  
Piezoelectric Vibration

In this paper, an attempt is made to determine the electric potential that would be generated in the piezoelectric vibration absorber using finite element piezoelectric analysis to determine optimal location for damping of first mode. Optimal placement of piezoelectric vibration absorber for passive vibration control of a cantilever composite plate is investigated. Finite element piezoelectric modal analysis is performed. Models based on placing piezoelectric vibration absorbers at five different locations on the surface of the plate and incorporating piezoelectric properties are built. Modal analysis is used to find the electric potential developed in the piezoelectric vibration absorber. The location that yields the highest amount of electric potential would be the best location for the vibration absorber. First bending mode of the cantilever composite plate is aimed for damping. Results of the analysis are verified with an experimental testing of the composite plate with piezoelectric vibration absorber firmly attached to the plate. A good agreement is found between the analytical and experimental results. Further, a resistive shunt circuit is designed for the passive damping of the first mode and attached to the vibration absorber in which the electric potential developed would be dissipated as heat to obtain passive vibration compensation. The experiment also demonstrates that a damping of 6 percent is obtained in the first mode and a great amount of damping is achieved in the second and third modes too.

Distributed Control of Truss Structures

2003 ◽  
Vol 9 (1-2) ◽  
pp. 7-23
Author(s):  
Sandrine Kevorkian ◽  
Madeleine Pascal
Keyword(s):  
Modal Analysis ◽  
Active Control ◽  
Distributed Control ◽  
Transfer Matrix ◽  
Closed Loop ◽  
Feedback Controller ◽  
Truss Structures ◽  
Flexible Beams ◽  
Performance Predictions

Continuous element methods have frequently been used in the modal analysis of structures modeled as flexible beams, extensible strings and rods, but only rarely for purposes of control. In this paper, we define a strategy of active control using the exact transfer matrix of a two-cell planar truss. The closed-loop performance predictions of both collocated and non-collocated controllers are compared as a function of feedback controller parameters.

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