Design And Performance Of An Intermittent Rib Floating Raft Vibration Isolation System

Floating raft isolation system is a widely used vibration isolation device onships.When the structure design of the floating raft isolation system is not reasonable,it will not only weaken the vibration isolation effect of the system,but also may enlarge the vibration energy transmitted to the base,even cause the resonance phenomenon of the part of the hull structure,which will greatly influence the working environment,stealth performance and operation life of the ship.Therefore,it is very important to optimize the vibration transfer characteristics of floating raft isolation system and improve its vibration isolation performance.Based on the Zhuzhou Electric Locomotive Institute's project “Design of a floating raft isolation system for a marine pump group”,a discontinuous ribbed raft was designed by introducing a horizontal discontinuous structure into a raft structure,and the dynamic characteristics and vibration transmission characteristics of the discontinuous ribbed raft isolation system were studied.The specific research contents are as follows:(1)The structure of the rib plate in the traditional raft is changed and the horizontal discontinuous ribs are added.A discontinuous ribbed raft structure is designed,and its three-dimensional model and finite element model are established.The dynamic characteristics of the raft are studied with the finite element software ANSYS combined with the modal analysis theory.The study shows that,compared with the traditional raft,more modes of the discontinuous ribbed raft is excited in the high frequency region,and there are more bending and torsion in the vibration mode.(2)The model of discontinuous ribbed raft isolation system is established,and the dynamic characteristics of the system are analyzed.It is known that the first few mode frequencies of the discontinuous ribbed raft are far greater than the first few mode frequencies of the discontinuous ribbed raft isolation system,which can avoid the resonance of the system in the low frequency region.It shows that the design of the discontinuous ribbed raft has a certain rationality.Then combined with the power flow theory,the vibration isolation performance of the discontinuous ribbed raft isolation system and the traditional floating raft isolation system is simulated,and the vibration isolation performance of the discontinuous ribbed raft isolation system is better than the traditional floating raft isolation system on the whole.(3)Study on vibration transfer characteristics of discontinuous ribs floating raft isolation system.Three kinds of vibration source parameters are set up with different phase difference,different amplitude difference and multi direction,and the vibration isolation effect of the discontinuous ribbed raft isolation system under different working conditions is simulated.The vibration isolation effect of the discontinuous ribbed raft isolation system under different working conditions,and the vibration isolation effect of the traditional floating raft isolation system and the intermittent ribbed raft isolation system under the same working conditions are analyzed.The vibration transfer characteristics of the intermittent ribbed raft isolation system are analyzed and studied,and some useful conclusions are obtained,which have some guidance for the practical engineering.