Study On Simulation And Application Of Particle Damping

Particle damping is a new technology for passive vibration control. It can provide damping for vibrating structures through the impact and friction between particles which are filled in the structural cavities. Particle damping is simple, cheap and effective, and can perform in harsh environment like high temperature, erosion and so on. In this thesis, the mechanism and effects of the particle damping are studied, and the application on helicopter blades is also investigated experimentally.The computer simulation of particle damping is based on the discrete element method (DEM). Using the DEM, we developed a Visual Basic software package to simulate the dynamic behaviour of the particles. Then as an example, the energy- dissipation property of a particular particle damper is evaluated using the package. The results are verified against experimental data, which shows that the software package is reliable.Experiments are conducted to evaluate the efficiency of the particle damping applied to non-rotating as well as rotating helicopter blades. For non-rotating blade model, we firstly measure its frequency response function (FRF), and then identify the first three damping ratios of the blade which can be used to estimate the particle damping. The experimental results indicate that the particle damping can notably improve the blade's damping ratio, but depends on the excitation level, damper location, particle fill ratio and particle diameter. Especially when the excitation level is higher, the impacts between the particles and the damper wall play more important role, which leads to great increase of the mode damping ratios.Vibration measurement for rotating blades is carried out by the test stand in the helicopter rotor laboratory, the effect of particle damping on rotating blades is investigated experimentally. After testing and comparing the acceleration response of the blades at different rotating speeds and various damping conditions, we find that particle damping in rotating state can overcome the centrifugal force, and therefore reduce the flap and lead-lag response of the rotating blades by a certain degree.