Research On Dynamic Characteristics And Passive Vibration Control Of Large Flexible Space Truss

With the development of astronautics, large flexible space truss (LFST) has been widely used in space structures. When these trusses are disturbed, low frequency, wide range and persistent vibration will happen. In order to ensure the spacecrafts will work, the vibration of trusses must be controlled fully. Thus, research on the vibration control of large flexible space truss has been taken as an important subject. Unfortunately, due to the structural complex and the non-linear characters. The accurate model is difficult to build up and the conventional control skill based on accurate model is faced with challenge. However, damped passive control theory is simple, reliable and effective, so it is suitable to the vibration control of the space truss. From this point of view, the dynamics of Large Flexible Space Truss has been researched in this thesis and one schemes of damped passive vibration control for LFST has been put forward also. The main studies included in this thesis are as follows:1. Analysis, classification and review were made on today's space truss. Three types of basic physical model of truss were proposed meanwhile truss structural finite element models were established using finite element theory.2. A brief damping model of viscoelastic material, including the model of classical and modern damping, was introduced. A common simple damping cylinder rod (VED) was designed, and its simplified mechanical model and the optimal allocation and other issues were discussed.3. On the basis of the truss finite element model, mechanical analysis, including static analysis and dynamic analysis, was carried on via finite element software. The aim of static analysis is to observe its deformation and stress under constant load, for determining the best location of damping rod. Through dynamic analysis, including modal analysis, harmonic analysis and transient response analysis, the natural frequencies and mode shapes were carried out by modal analysis, and the dynamic response of the truss under the external sinusoidal excitation and pulse were studied by using harmonic response analysis and transient analysis.4. The mechanical analysis and modal testing were made against the laboratory model of truss structures, and the ordinary rods were replaced by cylindrical rod in order to study the efficiency of damping passive control. The simulation results show that the vibration of te truss was controled effitively in the region of resonance, and the damping passive vibration control method for the large flexible space truss is of availability.