scholarly journals Particle Damping with Granular Materials for Multi Degree of Freedom System

2011 ◽  
Vol 18 (1-2) ◽  
pp. 245-256 ◽  
Author(s):  
Masanobu Inoue ◽  
Isao Yokomichi ◽  
Koju Hiraki
Keyword(s):  
Granular Materials ◽  
Equations Of Motion ◽  
Experimental Studies ◽  
Wide Frequency Range ◽  
Vertical Vibration ◽  
Degree Of Freedom ◽  
Particle Damping ◽  
Single Mass ◽  
Particle Dampers ◽  
Particle Bed

A particle damper consists of a bed of granular materials moving in cavities within a multi degree-of-freedom (MDOF) structure. This paper deals with the damping effects on forced vibrations of a MDOF structure provided with the vertical particle dampers. In the analysis, the particle bed is assumed to be a single mass, and the collisions between the granules and the cavities are completely inelastic, i.e., all energy dissipation mechanisms are wrapped into zero coefficient of restitution. To predict the particle damping effect, equations of motion are developed in terms of equivalent single degree-of-freedom (SDOF) system and damper mass with use made of modal approach. In this report, the periodic vibration model comprising sustained contact on or separation of the damper mass from vibrating structure is developed. A digital model is also formulated to simulate the damped motion of the physical system, taking account of all vibration modes. Numerical and experimental studies are made of the damping performance of plural dampers located at selected positions throughout a 3MDOF system. The experimental results confirm numerical prediction that collision between granules and structures is completely inelastic as the contributing mechanism of damping in the vertical vibration. It is found that particle dampers with properly selected mass ratios and clearances effectively suppress the resonance peaks over a wide frequency range.

Impact Damper With Granular Materials for Multibody System

1996 ◽  
Vol 118 (1) ◽  
pp. 95-103 ◽  
Author(s):  
I. Yokomichi ◽  
Y. Araki ◽  
Y. Jinnouchi ◽  
J. Inoue
Keyword(s):  
Granular Materials ◽  
Equations Of Motion ◽  
Degree Of Freedom ◽  
Mode Shapes ◽  
Maximum Displacement ◽  
Impact Damper ◽  
Particle Bed ◽  
Modal Mass ◽  
Three Degree Of Freedom ◽  
The Impact

An efficient impact damper consists of a bed of granular materials moving in a container mounted on a multibody vibrating system. This paper deals with the damping characteristics of a multidegree-of-freedom (MDOF) system that is provided with the impact damper when the damper may be applied to any point of the system. In the theoretical analysis, the particle bed is assumed to be a mass which moves unidirectionally in a container, and collides plastically with its end. Equations of motion are developed for an equivalent single-degree-of-freedom (SDOF) system and attached damper mass with use made of the normal mode approach. The modal mass is estimated such that it represents the equivalent mass on the point of maximum displacement in each of the vibrating modes. The mass ratio is modified with the modal vector to include the effect of impact interactions. Results of the analysis are applied to the special case of a three-degree-of-freedom (3DOF) system, and the effects of the damper parameteres including mode shapes and damper locations are determined. A digital model is also formulated to simulate the damped motion of the physical system.

Damping characteristics of particle dampers—some preliminary results

2001 ◽  
Vol 215 (3) ◽  
pp. 253-257 ◽  
Author(s):  
G R Tomlinson ◽  
D Pritchard ◽  
R Wareing
Keyword(s):  
Wide Frequency Range ◽  
Excitation Level ◽  
Vibration Absorbers ◽  
Frequency Range ◽  
Tuned Mass Dampers ◽  
Tuned Vibration Absorbers ◽  
Damping Characteristics ◽  
Particle Damping ◽  
Linear Behaviour ◽  
Particle Dampers

Particle dampers offer considerable potential for suppressing structural resonant conditions over a wide frequency range compared with tuned mass dampers or tuned vibration absorbers. However, they exhibit non-linear behaviour which relates to the motion of the particles that in turn is dependent on the excitation level. This communication describes some preliminary experimental results on the damping characteristics of a particle damping device which clearly show that the damping levels are dependent on the geometry of the device and the resulting motion of the particles arising from the level of the input excitation.

scholarly journals Damping prediction of particle dampers for structures under forced vibration using effective fields

2021 ◽  
Vol 23 (3) ◽  
Author(s):  
Niklas Meyer ◽  
Robert Seifried
Keyword(s):  
Energy Dissipation ◽  
Knowledge Exchange ◽  
Underlying Structure ◽  
Reduction Techniques ◽  
Linear Behavior ◽  
Damping Behavior ◽  
Effective Particle ◽  
Coupling Procedure ◽  
Particle Damping ◽  
Particle Dampers

AbstractParticle damping is a promising damping technique for a variety of technical applications. However, their non-linear behavior and multitude of influence parameters, hinder currently its wide practical use. So far, most researchers focus either on determining the energy dissipation inside the damper or on the overall damping behavior when coupled to a structure. Indeed, currently almost no knowledge exchange between both approaches occurs. Here, a bridge is build to combine both techniques for systems under forced vibrations by coupling the energy dissipation field and effective particle mass field of a particle damper with a reduced model of a vibrating structure. Thus, the overall damping of the structure is estimated very quickly. This combination of both techniques is essential for an overall efficient dimensioning process and also provides a deeper understanding of the dynamical processes. The accuracy of the proposed coupling method is demonstrated via a simple application example. Hereby, the energy dissipation and effective mass of the particle damper are analyzed for a large excitation range first using a shaker setup. The particle damper exhibits multiple areas of different efficiency. The underlying structure is modeled using FEM and modal reduction techniques. By coupling both parts it is shown that multiple eigenmodes of the structure are highly damped using the particle damper. The damping prediction using the developed coupling procedure is validated via experiments of the overall structure with particle damper.

A 3-DOF Friction-Free Planar Motor Using Piezoelectric Elements

2012 ◽  
Vol 523-524 ◽  
pp. 739-744 ◽  
Author(s):  
Akihiro Torii ◽  
Mitsuhiro Nishio ◽  
Yuki Itatsu ◽  
Kae Doki ◽  
Akiteru Ueda
Keyword(s):  
Flat Surface ◽  
Thrust Force ◽  
Levitation Force ◽  
Vertical Vibration ◽  
Degree Of Freedom ◽  
Horizontal Direction ◽  
Horizontal Deformation ◽  
Piezoelectric Elements ◽  
Three Degree Of Freedom

A friction-free planar motor, which is composed of piezoelectric elements (piezos), is proposed. The motor is based on the principle of an inchworm using levitation mechanisms. The vertical vibration of the piezo generates the levitation force of the motor. The horizontal deformation of the piezo causes the thrust force of the motor. These piezos realizes three degree-of-freedom motion on a flat surface. We measure the displacement in the vertical and horizontal direction of the levitation mechanism. The feasibility of the inchworm using levitation mechanisms is described.

scholarly journals A new approach to assess the influence of road roughness on driver speed behavior based on driving simulator tests

2016 ◽  
Vol 11 (2) ◽  
pp. 144-152 ◽  
Author(s):  
Mariano Pernetti ◽  
Mauro D’Apuzzo Mauro D’Apuzzo ◽  
Francesco Galante
Keyword(s):  
Driving Simulator ◽  
Experimental Studies ◽  
Vertical Vibration ◽  
The Other ◽  
Added Value ◽  
Published Data ◽  
Vehicle Speed ◽  
Safety Level ◽  
The Road ◽  
Road Roughness

Vehicle speed is one of main parameters describing driver behavior and it is of paramount importance as it affects the travel safety level. Speed is, in turn, affected by several factors among which in-vehicle vibration may play a significant role. Most of speed reducing traffic calming countermeasures adopted nowadays rely on vertical vibration level perceived by drivers that is based on the dynamic interaction between the vehicle and the road roughness. On the other hand, this latter has to be carefully monitored and controlled as it is a key parameter in pavement managements systems since it influences riding comfort, pavement damage and Vehicle Operating Costs. There is therefore the need to analyse the trade-off between safety requirements and maintenance issues related to road roughness level. In this connection, experimental studies aimed at evaluating the potential of using road roughness in mitigating drivers’ speed in a controlled environment may provide added value in dealing with this issue. In this paper a new research methodology making use of a dynamic driver simulator operating at the TEST Laboratory in Naples is presented in order to investigate the relationship between the driver speed behavior on one hand, and the road roughness level, road alignment and environment, vehicle characteristics on the other. Following an initial calibration phase, preliminary results seem fairly promising since they comply with the published data derived from scientific literature.

scholarly journals Liquidation of solid particles of polydispersed grained material

2020 ◽  
Vol 3 (10) ◽  
pp. 319-321
Author(s):  
Bakhronov Koshim Shayimovich ◽  
Khudoiberdieva Nazora Sharofovna ◽  
Yunusova Sitora Tolib qizi
Keyword(s):  
Granular Materials ◽  
Fluidized Bed ◽  
Experimental Studies ◽  
Solid Particles ◽  
General Picture

The results of experimental studies on the study of the expansion of the fluidized bed are presented. It is noted that the general picture of the expansion of the fluidized bed of polydisperse granular materials differs from monodisperse systems, and at the same time the porosity value of the pseudo-fluidized bed corresponds to the results of calculations according to the equations available in the literature.

Coupling Simulation Algorithm of Dynamic Feature of a Plate With Particle Dampers Under Centrifugal Loads

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Zhaowang Xia ◽  
Xiandong Liu ◽  
Yingchun Shan
Keyword(s):  
Vibration Suppression ◽  
Extreme Temperature ◽  
Extreme Environment ◽  
Dynamic Feature ◽  
Simulation Algorithm ◽  
Centrifugal Forces ◽  
Granular Particle ◽  
Particle Damping ◽  
Particle Dampers ◽  
Element Method

Particle damper comprises granular particle enclosed in a container within a vibrating structure. The performance of particle damper is strongly nonlinear whose energy dissipation is derived from a combination of mechanisms including plastic collisions and friction between particles or particles and cavity walls. Particle damper containing suitable materials may be effective in a wider temperature range than most other types of passive damping devices. Therefore, it may be applied in extreme temperature environments where most conventional dampers would fail. It may also attenuate vibrations over a broad range of frequencies and cost less. Researches have indicated that particle damper could be a viable option for extreme environment applications. However, to date, no effort has come forward the can prove analytically or numerically that the particle damping is a viable solution for vibration suppression under centrifugal forces. In this paper, a coupling simulation algorithm based on the discrete element method and finite element method and the results of simulative studies aimed at understanding the effects of parameters of particle damper under centrifugal forces are presented. And the results show that the presented coupling simulation algorithm is effective and the analyses of dynamic feature of a plate with particle dampers under centrifugal loads are reasonable.

A Comparison of the Effects of Nonlinear Damping on the Free Vibration of a Single-Degree-of-Freedom System

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Bin Tang ◽  
M. J. Brennan
Keyword(s):  
Free Vibration ◽  
Equations Of Motion ◽  
Nonlinear Damping ◽  
Degree Of Freedom ◽  
Damping Force ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Single Degree ◽  
Dependent Term ◽  
Quadratic Damping

This article concerns the free vibration of a single-degree-of-freedom (SDOF) system with three types of nonlinear damping. One system considered is where the spring and the damper are connected to the mass so that they are orthogonal, and the vibration is in the direction of the spring. It is shown that, provided the displacement is small, this system behaves in a similar way to the conventional SDOF system with cubic damping, in which the spring and the damper are connected so they act in the same direction. For completeness, these systems are compared with a conventional SDOF system with quadratic damping. By transforming all the equations of motion of the systems so that the damping force is proportional to the product of a displacement dependent term and velocity, then all the systems can be directly compared. It is seen that the system with cubic damping is worse than that with quadratic damping for the attenuation of free vibration.

Sign in / Sign up

Export Citation Format

Share Document