Identification of Equivalent Modal Damping and Frequencies in Multi Degree-of-Freedom Nonlinear Systems

2011 ◽  
Author(s):  
D. Dane Quinn ◽  
Richard J. Ott ◽  
Sean Hubbard ◽  
D. Michael McFarland ◽  
Lawrence A. Bergman ◽  
...  
Keyword(s):  
Nonlinear Systems ◽  
Time History ◽  
Degree Of Freedom ◽  
Vibration Absorber ◽  
Primary System ◽  
Vibration Modes ◽  
Structural System ◽  
Modal Damping ◽  
History Of ◽  
Two Degree Of Freedom

We consider the response of a linear structural system when coupled to an attachment containing strong or even essential nonlinearities. For this system, the attachment is designed as a nonlinear vibration absorber, serving to dissipate energy from the structural system. Moreover, the attachment not only leads to a reduction in the total energy of the system, but also couples together the vibration modes of the linear structural system, thereby allowing for energy to also be redistributed among these structural modes of the system. The effect of the nonlinear attachment on the linear primary system can be quantified in terms of equivalent measures for the damping and frequency of each mode, derived through consideration of the energy in each mode. The identification of these equivalent measures is illustrated on a two degree-of-freedom primary system. Moreover, this procedure depends only on the time history of the response and is therefore suited to both simulation and experimental results.

The Two-Degree-of-Freedom Tuned-Mass Damper for Suppression of Single-Mode Vibration Under Random and Harmonic Excitation

2005 ◽  
Vol 128 (1) ◽  
pp. 56-65 ◽  
Author(s):  
Lei Zuo ◽  
Samir A. Nayfeh
Keyword(s):  
Vibration Suppression ◽  
Single Mode ◽  
Tuned Mass Damper ◽  
Harmonic Excitation ◽  
Degree Of Freedom ◽  
Primary System ◽  
H Infinity ◽  
Mass Damper ◽  
Mode Vibration ◽  
Two Degree Of Freedom

Whenever a tuned-mass damper is attached to a primary system, motion of the absorber body in more than one degree of freedom (DOF) relative to the primary system can be used to attenuate vibration of the primary system. In this paper, we propose that more than one mode of vibration of an absorber body relative to a primary system be tuned to suppress single-mode vibration of a primary system. We cast the problem of optimization of the multi-degree-of-freedom connection between the absorber body and primary structure as a decentralized control problem and develop optimization algorithms based on the H2 and H-infinity norms to minimize the response to random and harmonic excitations, respectively. We find that a two-DOF absorber can attain better performance than the optimal SDOF absorber, even for the case where the rotary inertia of the absorber tends to zero. With properly chosen connection locations, the two-DOF absorber achieves better vibration suppression than two separate absorbers of optimized mass distribution. A two-DOF absorber with a negative damper in one of its two connections to the primary system yields significantly better performance than absorbers with only positive dampers.

Vibration Mode Structure of Cyclically Symmetric Centrifugal Pendulum Vibration Absorber Systems

2012 ◽  
Author(s):  
Chengzhi Shi ◽  
Robert G. Parker
Keyword(s):  
Degree Of Freedom ◽  
Vibration Absorber ◽  
Vibration Modes ◽  
Rotational Degree ◽  
Cyclic Symmetry ◽  
Mode Structure ◽  
Vibration Properties ◽  
Centrifugal Pendulum Vibration Absorber ◽  
Gyroscopic Effects ◽  
Modal Vibration

This work develops an analytical model of centrifugal pendulum vibration absorber systems with equally-spaced, identical absorbers and uses it to investigate the structure of the modal vibration properties. The planar model admits two translational and one rotational degree-of-freedom for the rotor and a single arclength degree-of-freedom for each absorber. The gyroscopic effects from rotor rotation are taken into account. Examination of the associated eigenvalue problem reveals well-defined structure of the vibration modes resulting from the cyclic symmetry of the absorbers. The vibration modes are classified into rotational, translational, and absorber modes. Characteristics of each mode type are analytically proved.

scholarly journals The Development of "Immigration to Europe" Topic in the Time History of Speech Pattern Changes on the TV News

2017 ◽  
Vol 6 (5) ◽  
pp. 327
Author(s):  
Galina L. Arsentyeva
Keyword(s):  
North Africa ◽  
Information Overload ◽  
Time History ◽  
Structural System ◽  
Cognitive Sciences ◽  
The Real ◽  
Mass Migration ◽  
New Information ◽  
Tv News ◽  
History Of

<p>The migration subject from the countries of North Africa and the Middle East to Europe was one of the main subjects of 2015-2016 on the Russian television, in particular, in information programs. In the real research we also explore the period from May 15 to May 22, 2017 with the purpose of tracking the appeal of journalists to this subject a year later after its active lighting in world media. At the same time the analysis of speech dynamics changes in texts of information programs on the basis of which conclusions on this research were drawn became a main objective. Let us note that several scientific approaches to a research of the television speech are known: lingual-and-stylistic, social-and-linguistic, psycho-linguistic, culturological, structural, system, functional approaches. In literature are in this regard described also effect of priming and cultivation. Besides, the new information era and a variety of information sources led to information overload which became a studying subject for representatives of cognitive sciences. Language and stylistic features of the television speech on an immigration subject in the real research are considered as a telespeech implementer in communication aspect. The research of its internal linguistic component, including phonetic implementers, became a basis of their studying. Results of the research conducted on the basis of the Kazan Federal University are given in the article. The author shows two-year speech dynamics changes in plots of information releases of the central TV channels with the universal programming strategy concerning a subject of mass migration to Europe. </p>

scholarly journals Pendekatan Eksperimen Karakteristik Respon Getaran Sistem Two Degree of Freedom dengan Penambahan Independent Dual Dynamic Vibration Absorber

2019 ◽  
Vol 3 (2) ◽  
pp. 85
Author(s):  
Susastro Susastro ◽  
Novi Indah Riani
Keyword(s):  
Vibration Reduction ◽  
Degree Of Freedom ◽  
The Other ◽  
Vibration Absorber ◽  
Dynamic Vibration Absorber ◽  
Maximum Reduction ◽  
Dynamic Vibration ◽  
Translational Vibration ◽  
Mathematical Equations ◽  
Two Degree Of Freedom

Vibration is one of the problems that must be reduced in a vehicle. There are many ways to reduce vibration in vehicles, one of them is by adding Dynamic vibration absorber (DVA). While Dual Dynamic vibration absorber (dDVA) is a DVA period that is able to move in the translational direction given to the system to reduce translation vibration and when there is resonance. Translation DVA is an additional type of time used to reduce the vibration of the translation direction. So far there is not much research related to the use of translational DVA to reduce rotational vibrations as well as translation. In this study, a study was conducted related to the use of independent double translational DVA (dDVA) to reduce translation vibrations as well as rotation of the beam. The research was conducted by modeling the system obtained into mathematical equations and simulations were carried out to determine the characteristics of vibrations that arise. In the simulation, one of the DVA periods is placed at the center of the main system period, while the other DVA period is given a change between the center period and the end of the system. The results of the study show that the maximum reduction in translational vibration is 95.51% and occurs when the absorber is placed at the center of the system, while the maximum rotation vibration reduction is 56.62% and is obtained when the system is given with an arm ratio of 1 and zero.

Optimization of a Two Degree of Freedom System Acting as a Dynamic Vibration Absorber

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
M. Febbo ◽  
S. A. Vera
Keyword(s):  
Simulated Annealing Algorithm ◽  
Degree Of Freedom ◽  
Vibration Absorber ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
System A ◽  
Annealing Algorithm ◽  
Minimum Amplitude ◽  
Two Degree Of Freedom ◽  
Heuristic Criterion

This paper deals with the problem of finding the optimal stiffnesses and damping coefficients of a two degree of freedom (2DOF) system acting as a dynamic vibration absorber (DVA) on a beam structure. In this sense, a heuristic criterion for the optimization problem will be developed to contemplate this particular type of DVA. Accordingly, it is planned to minimize the amplitude of vibration in predetermined points of the main structure. Two optimizations will be proposed for two DVAs of 1DOF to compare their performances with the optimized 2DOF system. A simulated annealing algorithm is used to obtain the DVA’s optimal parameters for minimum amplitude in a given point of the beam. The best configuration depends on the location of the absorbers on the beam and, for a fixed location, on the distribution of the stiffness constants.

Discussion: “Optimization of a Two Degree of Freedom System Acting as a Dynamic Vibration Absorber” (Febbo, M., and Vera, S. A., 2008, ASME J. Vib. Acoust., 130, p. 011013)

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Semin Chun ◽  
Hyunwook Baek ◽  
Tae-Hyoung Kim
Keyword(s):  
Degree Of Freedom ◽  
Vibration Absorber ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Asme Journal ◽  
Two Degree Of Freedom

We present this discussion on “Optimization of a Two Degree of Freedom System Acting as a Dynamic Vibration Absorber,” by M. Febbo and S. A. Vera, published in the Feb. 2008 issue of the ASME Journal of Vibration and Acoustics, Vol. 130, No. 1, p. 010013, and then derive the corrections in detail.

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