Dissipation energy of powder beds subject to vibration

This paper presents an investigation of damping mechanisms of vibrating bed s packed naturally at a low acceleration level (0.1 x g). In order to measu re the properties of powder beds subject to vibration, two experimental sys tems were used: (i) open-top system; (ii) top-cap system. The open-top syst em provides the dissipation energy of powder beds packed naturally. In the system, the force and acceleration at the bottom of powder bed, subject to sinusoidal vibration ranging from 50-1000Hz, were measured. Results were in terpreted in terms of the hysteresis loop to obtain the dissipation energy of bed per vibration cycle. Experiments were performed on a range of materi als including glass spheres and polyethylene powder. On the other hand, the top-cap system characterizes the elastic and damping properties of powder beds with the required top-cap mass. From the dynamic properties obtained u sing the top-cap system, the properties of the powder beds packed naturally were estimated, and the dissipation energy was deduced using viscoelastic theory based upon an equivalent viscous damping. Comparison between both sy stems, in terms of the dissipation energy, has been made, and good agreemen ts between the experimental data measured using the open-top system and the model calculated from results of the top-cap system were obtained. This ha s implications for the damping mechanisms and dynamics of powder beds subje ct to vibration.