Dissipation energy of powder beds subject to vibration

This paper presents an investigation of damping mechanisms of vibrating beds packed naturally at a low acceleration level (0.1 × g). In order to measure the properties of powder beds subject to vibration, two experimental systems were used: (i) Open-top system; (ii) Top-cap system. The open-top system 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 50-1000 Hz, were measured. Results were interpreted in terms of the hysteresis loop to obtain the dissipation energy of bed per vibration cycle. Experiments were performed on a range of materials 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 using 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 systems, in terms of the dissipation energy, has been made, and good agreements between the experimental data measured using the open-top system and the model calculated from results of the top-cap system were obtained. This has implications for the damping mechanisms and dynamics of powder beds subject to vibration.