Prediction of the amplitude dependent behaviour of particle dampers

Abstract

A particle damper (PD) comprises a granular material enclosed in a container that is attached to a vibrating structure. Vibration energy is dissipated by the damper through inelastic collisions and friction between particles. The main advantage of a particle damper is that its performance does not depend on temperature and can therefore be used in harsh environments where traditional approaches fail. One of the principal challenges in using particle dampers is that they display dramatic amplitude non-linearity. To be able to understand and design optimised dampers, the ability to predict the state of the granular material is seen as crucial. This paper presents initial work on developing models for predicting particle dampers behaviour using the Discrete Element Method (DEM). In the DEM approach, individual particles are typically represented as elements with mass and rotational inertia. Contacts between particles and with walls are represented using springs, dampers and sliding friction interfaces. In order to use DEM to predict damper behaviour adequately, it is important to identify representative models of the contact conditions. It is particularly important to get the appropriate trade-off between accuracy and computational efficiency as particle dampers have so many individual elements. In order to understand appropriate models, experimental work was carried out to understand interactions between the typically small (~ 1.5-3 mm diameter) particles used. Measurements were made of coefficient of restitution and interface friction. These were used to give an indication of the level of uncertainty that the simplest (linear) models might assume. These data were used to predict energy dissipation in a particle damper via a DEM simulation. The results were compared with that of an experiment.