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Granular Damping

Since granular materials are highly dissipative, they can be used to convert kinetic energy of many mechanical systems (such as machineries, buildings, vehicles, etc) into heat. This way, it is possible to design new damping devices based on granulars instead of viscous fluids. By means of discrete element method (DEM) simulations, we have characterized some of the damping features of a box filled with grains subjected to vibrations. See VIDEO

Some results

Optimal size of the enclosure

It has been shown that a particle damper (or granular damper) is efficient in a wide range of frequencies. However, variables such as the size and shape of the particles, size distribution, density and coefficient of restitution, friction coefficient, shape of the enclosure that contains the grains, type of excitation, vibration amplitude and frequency, among others, may have an impact in the efficiency.

When the amplitude of vibration or the height of the enclosure we can observe shifts of the frequency response function. When the particles are always in contact with the enclosure it is expected that the effective mass of the system is the sum of the primary mass and the mass of the grains. If the vibration is strong and grains rarely touch the boundaries the effective mass is expected to be cero.

Analyzing the effective mass in detail, we have found the these two limiting effective masses are not connected through a monotonic function.

By studding the motion of the granular bed and the force exerted on the floor and ceiling during collisions we are able to explain the origin of the non-monotonic response. A critical ingredient is the timing at which particles hit the enclosure. When the relative velocity between the granular bed and the enclosure is maximum just at impact time, the highest attenuetion of the vibration is achieved.

We have developed a method to obtain the optimum size of the enclosure to reach the maximum damping performance.

 

Publications

TituloAutoresPublicado enAño
Tesis: Estudio de mecanismos de amortiguación de vibraciones mecánicas mediante el uso de partículas disipativas.M. SánchezUniversidad Tecnológica Nacional2012
Effect of particle shape and fragmentation on the
response of particle dampers
M. Sánchez, C. M. Carlevaro, L. A. PugnaloniJournal of Vibration and Control 20, 1846-18542014
Nonlinear dynamic analysis of an optimal particle damperM. Sánchez, C. M. Carlevaro,Journal of Sound and Vibration 332, 2070-2080 2013
Universal response of optimal granular damping devices
M. Sánchez, G. Rosenthal, L. A. PugnaloniJournal of Sound and Vibration 331, 4389-43942012
Effective mass overshoot in single degree of freedom mechanical systems with a particle damperM. Sánchez, L. A. Pugnaloni

Journal of Sound and Vibration 330, 5812-5819 2011
Modelado de un amortiguador granular
M. Sánchez, L.A. PugnaloniMecánica Computacional 29, 1849-18592010