Performance of Particle Dampers Under Random Excitation

1996 ◽  
Vol 118 (4) ◽  
pp. 614-621 ◽  
Author(s):  
A. Papalou ◽  
S. F. Masri
Keyword(s):  
Wide Band ◽  
Small Mass ◽  
Random Excitation ◽  
Primary System ◽  
Mass Ratio ◽  
Impact Damper ◽  
Mean Square Response ◽  
Small Model ◽  
Particle Dampers ◽  
Auxiliary Mass

An experimental and analytical study is made of the performance of particle dampers under wide-band random excitation. A small model, provided with a nonlinear auxiliary mass damper, was used to investigate the major system parameters that influence the performance of particle dampers: total auxiliary mass ratio, particle size, container dimension, and the intensity and direction of the excitation. It is shown that properly designed particle dampers, even with a relatively small mass ratio, can considerably reduce the response of lightly damped structures. An approximate analytical solution, which is based on the concept of an equivalent single unit-impact damper, is presented. It is shown that the approximate solution can provide an adequate estimate of the root-mean-square response of the randomly excited primary system when provided with a particle damper that is operating in the vicinity of its optimum range of parameters.

Transient Response of MDOF Systems With Inerters to Nonstationary Stochastic Excitation

2017 ◽  
Vol 84 (10) ◽  
Author(s):  
Sami F. Masri ◽  
John P. Caffrey ◽  
Hui Li
Keyword(s):  
Degrees Of Freedom ◽  
Broad Band ◽  
Primary System ◽  
Mean Square ◽  
Stochastic Excitation ◽  
Mass Ratio ◽  
Tuning Parameters ◽  
Mdof Systems ◽  
Mean Square Response ◽  
Arbitrary Location

Explicit, closed-form, exact analytical expressions are derived for the covariance kernels of a multi degrees-of-freedom (MDOF) system with arbitrary amounts of viscous damping (not necessarily proportional-type), that is equipped with one or more auxiliary mass damper-inerters placed at arbitrary location(s) within the system. The “inerter” is a device that imparts additional inertia to the vibration damper, hence magnifying its effectiveness without a significant damper mass addition. The MDOF system is subjected to nonstationary stochastic excitation consisting of modulated white noise. Results of the analysis are used to determine the dependence of the time-varying mean-square response of the primary MDOF system on the key system parameters such as primary system damping, auxiliary damper mass ratio, location of the damper-inerter, inerter mass ratio, inerter node choices, tuning of the coupling between the damper-inerter and the primary system, and the excitation envelope function. Results of the analysis are used to determine the dependence of the peak transient mean-square response of the system on the damper/inerter tuning parameters, and the shape of the deterministic intensity function. It is shown that, under favorable dynamic environments, a properly designed auxiliary damper, encompassing an inerter with a sizable mass ratio, can significantly attenuate the response of the primary system to broad band excitations; however, the dimensionless “rise-time” of the nonstationary excitation substantially reduces the effectiveness of such a class of devices (even when optimally tuned) in attenuating the peak dynamic response of the primary system.

Investigation of dynamic characteristics of rolling particle dampers

2020 ◽  
pp. 107754632095745
Author(s):  
Takuya Kuriyama ◽  
Masato Saeki
Keyword(s):  
Granular Materials ◽  
Particle Diameter ◽  
Rotating Cylinder ◽  
Vibration Absorber ◽  
Harsh Environment ◽  
Primary System ◽  
Mass Ratio ◽  
Curved Track ◽  
Particle Dampers ◽  
Inside Wall

In this article, the investigation of the use of a rolling particle damper under sinusoidal excitation is described. A rolling particle damper is a type of ball vibration absorber and consists of a rotating cylinder placed on a curved track mounted on a primary system. The rotating cylinder is partially filled with granular materials. When the rotating cylinder rolls inside the curved track, the granular materials also move. The friction between the granular materials and the inside wall of the rotating cylinder results in some energy dissipation. A rolling particle damper can be adopted in a harsh environment because it can be operated in a wide temperature range. The effects of the mass ratio, the particle material, and the particle diameter on the damping performance were examined experimentally. To elucidate the behavior of the entire system in detail, a numerical solution using the discrete element method was established. The predicted damping results were compared with experimental results for various mass ratios. In addition, the effect of the frequency ratio on the highest displacement amplitude of the primary system was examined referring to the numerical results.

Random Excitation of a Nonlinear Vibration Neutralizer

1978 ◽  
Vol 100 (4) ◽  
pp. 681-689 ◽  
Author(s):  
S. F. Masri ◽  
S. J. Stott
Keyword(s):  
Approximate Analytical Solution ◽  
Random Excitation ◽  
Analog Computer ◽  
Primary System ◽  
Experimental Measurements ◽  
Dynamic Vibration ◽  
Power Spectral ◽  
Highly Nonlinear ◽  
Mass Damper ◽  
Auxiliary Mass

An approximate analytical solution is obtained for the stationary response of a highly nonlinear auxiliary mass damper (a dynamic vibration neutralizer with motion-limiting stops) attached to an oscillator that is subjected to random excitation. Experimental measurements with an electronic analog computer and numerically simulated solutions generated by means of a digital computer verify the findings. Results are given for the power spectral density and root-mean-squared level of the response. The effects of various damper parameters on the response of the primary system are determined. The nonlinear damper under consideration is shown to be significantly more effective than the conventional dynamic vibration neutralizer in controlling the response of systems subjected to random excitation.

Shock-Based Experimental Investigation of the Linear Particle Chain Impact Damper

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Mohamed Gharib ◽  
Mansour Karkoub
Keyword(s):  
Frame Structure ◽  
Primary System ◽  
Mass Ratio ◽  
Linear Arrangement ◽  
Single Degree Of Freedom ◽  
Impact Damper ◽  
Single Degree ◽  
Particle Chain ◽  
The Common ◽  
Freely Moving

Impact dampers (IDs) provide an effective, economical, and retrofittable solution to the vibration problem in several engineering applications. An ID typically consists of a single or multiple masses constrained between two or more stops and attached to a primary system to be controlled. The latest developed type in the IDs family is the linear particle chain (LPC) ID. It consists of a linear arrangement of two sizes of freely moving masses, constrained by two stops. The high number of impacts among the damper masses leads to rapid energy dissipation compared to the common IDs. This paper presents an experimental study on the effectiveness of the LPC ID in reducing the vibrations of a single degree-of-freedom (SDOF) frame structure under different shock excitations. Prototypes of the LPC and conventional IDs with different geometric parameters are fabricated. The structure is excited by either an impact at the top floor or pulses at its base. The damping effect of the LPC ID is compared with that of conventional IDs. The experimental outcomes clearly show that the LPC ID can effectively reduce the response of simple structures under shock excitation. Additional investigations are conducted to examine the LPC ID sensitivity to the main damper parameters, such as the chain length, damper mass ratio, and damper clearance.

Transient Response of a SDOF System With an Inerter to Nonstationary Stochastic Excitation

2017 ◽  
Vol 84 (4) ◽  
Author(s):  
Sami F. Masri ◽  
John P. Caffrey
Keyword(s):  
Degrees Of Freedom ◽  
Analytical Study ◽  
Broad Band ◽  
Primary System ◽  
Stochastic Excitation ◽  
Mass Ratio ◽  
Vibration Damper ◽  
Tuning Parameters ◽  
Mass Damper ◽  
Mean Square Response

An analytical study is presented of the covariance kernels of a damped, linear, two-degrees-of-freedom (2DOF) system which resembles a primary system that is provided with an auxiliary mass damper (AMD), in addition to an “inerter” (a device that imparts additional inertia to the vibration damper, hence magnifying its effectiveness without a significant damper mass addition). The coupled 2DOF system is subjected to nonstationary stochastic excitation consisting of a modulated white noise. An exponential function, resembling the envelope of a typical earthquake, is considered. Results of the analysis are used to determine the dependence of the peak transient mean-square response of the system on the damper/inerter tuning parameters, and the shape of the deterministic intensity function. It is shown that, under favorable dynamic environments, a properly designed auxiliary damper, encompassing an inerter with a sizable mass ratio, can significantly attenuate the response of the primary system to broad band excitations; however, the dimensionless “rise-time” of the nonstationary excitation substantially reduces the effectiveness of such a class of devices (even when optimally tuned) in attenuating the peak dynamic response of the primary system.

Stationary and Transient Response of Cylindrical Shells Under Random Excitation

1988 ◽  
Vol 110 (2) ◽  
pp. 205-209
Author(s):  
A. V. Singh
Keyword(s):  
Transient Response ◽  
Random Vibration ◽  
Time History ◽  
Wide Band ◽  
Random Excitation ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
History Of ◽  
The Mean ◽  
Random Vibration Analysis

This paper presents the random vibration analysis of a simply supported cylindrical shell under a ring load which is uniform around the circumference. The time history of the excitation is assumed to be a stationary wide-band random process. The finite element method and the condition of symmetry along the length of the cylinder are used to calculate the natural frequencies and associated mode shapes. Maximum values of the mean square displacements and velocities occur at the point of application of the load. It is seen that the transient response of the shell under wide band stationary excitation is nonstationary in the initial stages and approaches the stationary solution for large value of time.

Mean-Square Response of a Second-Order System to Nonstationary, Random Excitation

1970 ◽  
Vol 37 (3) ◽  
pp. 612-616 ◽  
Author(s):  
L. L. Bucciarelli ◽  
C. Kuo
Keyword(s):  
Narrow Band ◽  
Random Excitation ◽  
Second Order ◽  
Envelope Function ◽  
Order System ◽  
Mean Square ◽  
Forcing Function ◽  
Mean Square Response ◽  
Noise Function ◽  
The Mean

The mean-square response of a lightly damped, second-order system to a type of non-stationary random excitation is determined. The forcing function on the system is taken in the form of a product of a well-defined, slowly varying envelope function and a noise function. The latter is assumed to be white or correlated as a narrow band process. Taking advantage of the slow variation of the envelope function and the small damping of the system, relatively simple integrals are obtained which approximate the mean-square response. Upper bounds on the mean-square response are also obtained.

scholarly journals UY Ursae Majoris: A W-subtype W UMa system with a small mass ratio

2001 ◽  
Vol 370 (2) ◽  
pp. 507-512 ◽  
Author(s):  
Y. Yang ◽  
Q. Liu ◽  
K.-C. Leung
Keyword(s):  
Small Mass ◽  
Mass Ratio

Wide-band random excitation of beams and rectangular plates coupled to discrete substructures

1989 ◽  
Vol 6 (2-4) ◽  
pp. 87-97 ◽  
Author(s):  
Lawrence A. Bergman ◽  
D. Michael McFarland
Keyword(s):  
Wide Band ◽  
Random Excitation ◽  
Rectangular Plates

On the nonlinear performance of a tuned sloshing damper under small amplitude excitation

2019 ◽  
Vol 25 (21-22) ◽  
pp. 2695-2705 ◽  
Author(s):  
Anuja Roy ◽  
Zili Zhang ◽  
Aparna (Dey) Ghosh ◽  
Biswajit Basu
Keyword(s):  
Small Amplitude ◽  
Numerical Study ◽  
Nonlinear Behavior ◽  
Wave Theory ◽  
Small Mass ◽  
Mass Ratio ◽  
Hybrid Testing ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Nonlinear Performance

This paper explores the potential of a tuned sloshing damper (TSD) in the control of small amplitude vibrations, which is often important from serviceability considerations, through the use of a relatively small mass ratio of the damper liquid. To investigate the nonlinear behavior of the TSD, real-time hybrid testing is conducted in which a single rectangular tank containing water constitutes the prototype TSD. The structure is modeled as a multi-degree-of-freedom system. Two different base input motions, namely harmonic and synthetically generated broad-banded input, are considered. The sensitivity of the TSD performance to tuning ratio vis-à-vis low mass ratio is studied. The experimental results are compared with those obtained from a numerical study carried out using the shallow water wave theory-based nonlinear, semi-empirical model, for the simulation of the sloshing motion of the TSD liquid (water). Results indicate that in the tuned condition, even with a low mass ratio, the TSD is highly effective in the suppression of the small amplitude vibrations, which is underestimated by the simulation model.

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