Vibration Transmission Characteristic Analysis Of Coupling Structures By Energy Flow Finite Element Method

Energy Flow Finite Element Method (EFFEM) is applicable in all frequency range and capable of providing more vibration detail information in built-up structures, and it is now the focus in the field of vibration control. Based on above viewpoint, this dissertation supported by the project of National Natural Science Foundation of China (NSFC) "The Intelligent Control Research of Complicated Flexible Vibration System Based on Power Flow Finite Element Method" (No.50805088), concentrated on power flow theory of one-dimensional structures, energy transmission coefficient in coupled-structure and the application of EFFEM in frame structures.The power flow theory is extended to the application in one-dimensional structures with flexible boundaries, and energy density equation of it is established. The result shows that, all kinds of beams with different boundaries could be simulated by simply change the stiffness of the supporting springs.Energy transmission coefficients of rigid and flexible one-dimensional-coupled structures are deduced, and the case of un-rigid branch beams is discussed extensively. The result shows that, the energy transmission coefficient is influenced by the stiffness of spring and frequency of excitation:Low stiffness (of the spring) and high frequency (of the excitation) can weak the effect of energy transmission, which means they are good for isolation.The global EFFEM equation of composite frame structure is established, before which, couple matrix of it is deduced firstly, then, energy density of each beam in the frame are calculated. At last, the energy density and power flow of the frame structure is analyzed by AutoSEA2, which is the special tool used in Statistic Energy Analysis (SEA) method, and we found that the results concluded by two methods are the same.The energy flow characteristic of single-layer vibration isolation system is analyzed by EFFEM and power flow mobility techniques, for the equipment and base are elastic, so both the stiffness dynamical mobility and elastic mobility are considered. The results obtained by the two methods are the same when the frequency is above 100Hz.