Time Varying Passive Vibration Absorption for Flexible Structures

1996 ◽  
Vol 118 (1) ◽  
pp. 36-40 ◽  
Author(s):  
R. Quan ◽  
D. Stech
Keyword(s):  
Computer Simulation ◽  
Experimental Work ◽  
Flexible Structures ◽  
Flexible Structure ◽  
Vibration Absorber ◽  
Time Varying ◽  
Vibration Absorbers ◽  
Switching Scheme ◽  
Vibration Absorption

A time varying extension of the passive vibration absorber is described, which increases the effectiveness of a small number of passive vibration absorbers on large or changing flexible structures. Initially, the extended absorber is targeted on a subset of the modes of the flexible structure. A stable switching scheme is described, which allows the absorber to target different subsets of modes, or to adapt to changes in the flexible structure. Computer simulation and experimental work are given which demonstrate the effectiveness of the extended absorber.

Nonlinear Torsional Vibration Absorber for Flexible Structures

2018 ◽  
Vol 86 (2) ◽  
Author(s):  
Xiao-Ye Mao ◽  
Hu Ding ◽  
Li-Qun Chen
Keyword(s):  
High Efficiency ◽  
Rotation Angle ◽  
Flexible Structures ◽  
Nonlinear Energy Sink ◽  
Flexible Structure ◽  
Vibration Absorber ◽  
Special Perturbation ◽  
Energy Sink ◽  
Simulation Parameters ◽  
Nonlinear Energy

A new kind of nonlinear energy sink (NES) is proposed to control the vibration of a flexible structure with simply supported boundaries in the present work. The new kind of absorber is assembled at the end of structures and absorbs energy through the rotation angle at the end of the structure. It is easy to design and attached to the support of flexible structures. The structure and the absorber are coupled just with a nonlinear restoring moment and the damper in the absorber acts on the structure indirectly. In this way, all the linear characters of the flexible structure will not be changed. The system is investigated by a special perturbation method and verified by simulation. Parameters of the absorber are fully discussed to optimize the efficiency of it. For the resonance, the maximum motion is restrained up to 90% by the optimized absorber. For the impulse, the vibration of the structure could attenuate rapidly. In addition to the high efficiency, energy transmits to the absorber uniaxially. For the high efficiency, convenience of installation and the immutability of linear characters, the new kind of rotating absorber provides a very good strategy for the vibration control.

Application of Parallel Mechanism in Multi-DIM Vibration Absorbers

2014 ◽  
Vol 532 ◽  
pp. 297-300 ◽  
Author(s):  
Chang Chun Yu
Keyword(s):  
Parallel Mechanism ◽  
Simple Structure ◽  
High Accuracy ◽  
New Method ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Parallel Mechanisms ◽  
Vibration Absorption ◽  
Absorption Field ◽  
Compact Mechanism

It introduces ways and means of designing this kind of vibration absorbers which are presented using parallel mechanisms as the main mechanisms ,it ,which takes the parallel mechanisms with 3-DOF translation as an example, validates the feasibility of the method, and enumerates some of the parallel mechanisms that are fit for multi-DIM vibration absorber. In a word, the multi-DIM vibration absorber system based on parallel mechanism is a new idea and breakthrough in multi-DIM vibration absorption field, which has the characteristic of simple structure, compact mechanism, high accuracy, partially or fully decoupled mechanism easy for control and so on, and provides a new method for the study of Multi-DIM vibration.

Design and control of adaptive vibration absorber for multimode structure

2019 ◽  
Vol 30 (7) ◽  
pp. 1043-1052 ◽  
Author(s):  
Jin-Siang Shaw ◽  
Cheng-An Wang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Fuzzy Logic Controller ◽  
Vibration Suppression ◽  
Experimental Testing ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Vibration Absorption ◽  
Resonant Modes ◽  
And Control

In this study, we used two tunable vibration absorbers composed of shape memory alloy to reduce vibration of a platform structure. The natural frequency of the shape memory alloy absorber can be tuned online using a fuzzy logic controller to change the axial force of the shape memory alloy wires through phase transformation. In addition, we employed the finite element method to analyze the dynamic characteristics of the multimode platform structure and to evaluate the effectiveness of the shape memory alloy vibration absorber in terms of platform vibration attenuation. Experimental testing of the platform structure was conducted to verify its modal characteristics. By setting the two shape memory alloy tunable vibration absorbers on two adjacent sides of the platform at 90 degrees to each other and offset from the platform’s center axes, it is shown that all six modes can be covered for vibration absorption. The experiments show that the vibration due to all six mode modal excitations can be attenuated by more than 7.49 dB using the shape memory alloy tunable vibration absorber. Specifically, at the fourth, fifth, and sixth resonant modes, an average of 16.68 dB vibration suppression is observed. Overall, an average of 12.69 dB vibration suppression is achieved for resonant excitation of the entire platform structure when using the designed shape memory alloy tunable vibration absorber.

scholarly journals On-Line Modal Parameter Identification Applied to Linear and Nonlinear Vibration Absorbers

Actuators ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 119
Author(s):  
Luis Gerardo Trujillo-Franco ◽  
Gerardo Silva-Navarro ◽  
Francisco Beltran-Carbajal ◽  
Eduardo Campos-Mercado ◽  
Hugo Francisco Abundis-Fong
Keyword(s):  
Nonlinear Dynamic ◽  
Degrees Of Freedom ◽  
Flexible Structure ◽  
Primary System ◽  
Vibration Absorbers ◽  
Modal Parameter ◽  
Vibration Absorption ◽  
Dynamic Vibration ◽  
On Line ◽  
Linear And Nonlinear

A solution of the vibration attention problem on a flexible structure from a dynamic vibration absorption perspective is experimentally and numerically studied in this article. Linear and nonlinear dynamic vibration absorbers are properly implemented on a primary structure of n degrees of freedom through a modal decomposition analysis and using the tuning condition when the primary system has one single degree of freedom. A time-domain algebraic identification scheme for on-line modal parameter estimation of flexible structures is presented. A fast frequency estimation of harmonic excitation force is also obtained. A Hilbert transform analysis of the frequency response function for the case of nonlinear dynamic vibration absorption is introduced. In this way, influence of this particular passive nonlinear control device on system dynamic response can be determined. The proposed approach is validated on an harmonically perturbed building-like structure, which is discretized in a finite number of degrees of freedom. The flexible structure is subjected to resonant operational conditions, and coupled to a pendulum vibration absorber configured as a tuned mass damper as well as an autoparametric system.

Simultaneous Optimization of Positioning and Vibration Controls Using Time-Varying Criterion Function

1994 ◽  
Vol 6 (4) ◽  
pp. 278-284 ◽  
Author(s):  
Susumu Hara ◽  
◽  
Kazuo Yoshida ◽  
Keyword(s):  
Optimal Control ◽  
Flexible Structures ◽  
Simultaneous Optimization ◽  
Flexible Structure ◽  
Time Varying ◽  
Criterion Function ◽  
Residual Vibration ◽  
Positioning Control

For the positioning control of flexible structures, it is important to reduce residual vibration after the positioning is completed. If a positioning controller and a vibration controller are designed independently and abrupt switching is performed from the former to the latter, the moving structure suffers from impact, and additional vibration is caused. This paper presents a method for simultaneously synthesizing both motion and vibration controllers, using a time-varying criterion function for optimal control. This method is applied to the positioning control of a flexible structure. The usefulness of the method is verified theoretically and experimentally.

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.

Vibration control using a beam-like adaptive tuned vibration absorber with an actuator-incorporated mass element

2009 ◽  
Vol 223 (7) ◽  
pp. 1555-1567 ◽  
Author(s):  
P Bonello ◽  
K H Groves
Keyword(s):  
Vibration Control ◽  
Effective Mass ◽  
Tuning Range ◽  
Excitation Frequency ◽  
Vibration Absorber ◽  
Time Varying ◽  
Additional Advantage ◽  
Expected Performance ◽  
Vibration Attenuation ◽  
Tuned Vibration Absorber

An adaptive tuned vibration absorber (ATVA) can retune itself in response to a time-varying excitation frequency, enabling effective vibration attenuation over a range of frequencies. For a wide tuning range the ATVA is best realized through the use of a beam-like structure whose mechanical properties can be adapted through servo-actuation. This is readily achieved either by repositioning the beam supports (‘moveable-supports ATVA’) or by repositioning attached masses (‘moveable-masses ATVA’), with the former design being more commonly used, despite its relative constructional complexity. No research to date has addressed the fact that the effective mass of such devices varies as they are retuned, thereby causing a variation in their attenuation capacity. This article derives both the tuned frequency and effective mass characteristics of such ATVAs through a unified non-dimensional modal-based analysis that enables the designer to quantify the expected performance for any given application. The analysis reveals that the moveable-masses concept offers significantly superior vibration attenuation. Motivated by this analysis, a novel ATVA with actuator-incorporated moveable masses is proposed, which has the additional advantage of constructional simplicity. Experimental results from a demonstrator correlate reasonably well with the theory, and vibration control tests with logic-based feedback control demonstrate the efficacy of the device.

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.

Real-Time Tuning of Delayed Resonator-Based Absorbers for Spectral and Spatial Variations

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Ryan Jenkins ◽  
Nejat Olgac
Keyword(s):  
Real Time ◽  
Active Control ◽  
Design Guidelines ◽  
Spatial Variations ◽  
Time Varying ◽  
Vibration Absorption ◽  
Spatial Tuning ◽  
System Components ◽  
Hybrid Concept ◽  
Time Variations

This paper offers two interlinked contributions in the field of vibration absorption. The first involves an active tuning of an absorber for spectral and spatial variations. The second contribution is a set of generalized design guidelines for such absorber operations. “Spectral” tuning handles time-varying excitation frequencies, while “spatial” tuning treats the real-time variations in the desired location of suppression. Both objectives, however, must be achieved using active control and without physically altering the system components to ensure practicality. Spatial tuning is inspired by the concept of “noncollocated vibration absorption,” for which the absorber location is different from the point of suppression. This concept is relatively under-developed in the literature, mainly because it requires the use of part of the primary structure (PS) as the extended absorber—a delicate operation. Within this investigation, we employ the delayed resonator (DR)-based absorber, a hybrid concept with passive and active elements, to satisfy both tuning objectives. The presence of active control in the absorber necessitates an intriguing stability investigation of a time-delayed dynamics. For this subtask, we follow the well-established methods of frequency sweeping and D-subdivision. Example cases are also presented to corroborate our findings.

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