| PD (Paritcle Damping) technology is also called powder damping technology. It is a new particle damping technology developed since 1990's in the field of vibration control. Particles are packed into a sealed container. The vibration energy of the system is dissipated by the frictional and impact movement of the particles, so the vibration is attenuated gradually. It has a lot of advantages such as: it can be used in wide range environment, the structures of original system are modified very little, the effect of vibration absorption is notable, additional mass added to the original system is very little, etc. These advantages attracted more and more attention of scholars from different fields. A new concept of particle damper is put forward based on the vibration characteristics of PD in the dissertation. And the theoretical analysis, numerical simulation and vibration experiment are combined to study the key factors that influence vibration characteristics of PD. The development history and current situation of DEM, powder mechanics, impact damping, optimization of experiments and power flow have been reviewed in the thesis. Some helpful exploration about the vibration characteristics of PD in the field of vibration isolation have been carried out by combining theoretical analysis, numerical simulation with vibration isolation experiment.Considering the complexity of the research, the DEM model of PD is established based on the principles and algorithm of DEM. Moreover, the main factors that influence the damping ratio is picked out and the variation regularities are disclosed.The characteristics of PD are explored through the experiment method. The powder mechanics model of PD including the shape and dimension of the container -one of the main factors is established. The effects of the stimulation force and dimension of the containers on the damping efficiency are studied by the model.The inner force of in PD is studied and the vibration model is built based on the theory of multi-phase flow. The correctness of the model is testified. The damping characteristics of PD are studied through analyzing the dynamic response of the system. The special damping capacity of PD is used to describe the characteristics. Furthermore, some meaningful conclusions are drawn by study the capacity under different conditions.Orthogonal experiment design is carried out including the factors of the density and diameter of particles and packing ratio to establish the regression model of PD in order to study the other main factors'effects and the interaction between the factors. The design parameters are optimized based on the non-linear optimum design.The effects of the PD distribution are studied through the power flow method. The vibratory responses of the stiffened plate with PD are solved by using the Laplace transmission method, and the corresponding mathematical expressions of vibration power flows are proposed. The vibration power flows of the structures with different kinds of ribs and under various load locations are numerically analyzed. Theoretical and experimental studies show that the peak values of power flows and the transmission power flows can be restrained in case of the container being filed with particles, and the energy can be received easily from the vibration source with PD at the stimulating point rather than the other locations.At last, the damping ratio of PD and the plate without PD are measured by experiments. The input power flows and the transmission power flows are measured in order to verify the correct and efficiency of the theoretical deduction of last chapter.In summary, the vibration attenuation performances of PD are analyzed in details by theoretical analysis, numerical simulation and experimental study in the dissertation, which has offered some theoretical foundation and governing principle for practical application. The research results have important theory significance and engineering application value for promoting PD in reducing vibration and lowering noise at low frequency.
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