Power Flow Finite Element Analysis Of Coupling Structures And Its Application In Stiffened Plates

Power Flow Finite Element Method (PFFEM), which is applicable in all frequency range and capable of providing more detail vibration information in built-up structures, is widely favored by the researchers and are becoming a hot method of vibration and noise prediction in recent years. Based on the above viewpoint, this dissertation, which is supported by the project of National Natural Science Foundation of China (NSFC)"Investigation on intelligent control of complex flexible vibration systems based on power flow finite element analysis"(No.50805088) and Foundation of State Key Laboratory of Automobile Dynamic Simulation at Jilin University "Active control of the vibration and noise of vehicle cabs based on power flow finite element analysis", is concentrated on power flow theory of two-dimensional structures, energy transfer coefficients in coupled-structures and application of PFFEM in complex structures. The major contents and achievements of this study are listed as follows:The presented study analyzes the energy transfer characteristics of one and two dimensional complex coupled structures. The energy transfer coefficients of the beam-plate coupling structures are deduced in detail. The results shows that the energy transfer coefficients of the beam-plate coupling structures are related to the driving frequency and the incident angle of waves. However, scattered field will be formed when several models are aroused, and then the coefficients should be averaged according to the incident angles.On the basis of obtaining the energy transfer coefficients and according to the analyses of coupled relations, the presented study deduces the coupled matrix which demonstrates the relationship between power flow and field variables, i.e. energy density. The integral equation of the power flow finite element is established for the beam-plate coupling structures. The energy density of each unit in the structures is calculated and visualized with Matlab in order to get the clear picture of the energy distributions and ways of energy transfer in the whole structure. This study applies the power flow finite element method to the stiffened plates by cross beams to obtain the energy density distributions and the transfer routes of power flow in the structures, which can provide a positive guidance for vibration isolation and optimal design of vibrating structures.