Power Flow Transmission Characters Of Raft Isolation System And Raft Shelf Finite Element Analysis On Dynamics

Raft isolation system is a good approach of controlling vibration, and this system has been successfully used in navigation. Compared with engineering application, there are many theoretical issues to be resolved. It is very useful to study the theory of the raft isolation system, because it can reduce the vibration of the machine, and approve operating condition of machine.Vibration power flow is a very important method for analysis of vibration control of complex structure, which considering both strength and rapidity, and the conclusion is emphasis for engineering application.Based on the inspection of a large number of domestic and foreign literature, the paper study model establishment and finite element numerical calculation. The details as following:The advantages and shortages of vibration and noise controlling methods are concluded. The dynamic model of raft isolation system is established, and power flow transmission function of the system is derived, then power flow transmission spectrum is emulated and calculated. The effects of vibration isolation are estimated from the viewpoint of vibration power transmission, and the influence of structural parameters, such as raft mass, isolator stiffness and damp and base stiffness and damp, on Power flow transmission spectrum is systemically studied. The general standard of choosing structural parameters is provided for the design of floating raft.The dynamic characteristic of raft isolation system is analyzed by use of ANSYS software. Firstly, the natural frequency and vibration shapes of the raft isolation system were calculated by mode analysis. The calculating results showed that the natural frequency of the raft isolation system present relatively dense distribution. Degree of dispersion of the natural frequency of the raft isolation system should be improved in order to improve the vibration isolation effect in a broader band. Secondly, analysis of strain and stress of raft isolation system is analyzed by static analysis, the calculating results showed that upper isolators should select different type according to the forces. At last, an introduction of the application of experimental modal analysis to raft isolation system is given.