Research On The Semi-active Switch Control Of Floating Raft Isolation System

The floating raft is a type of vibration isolation device widely used in ships,whose vibration isolation performance is excelent.It is possible to improve the vibration isolation performance of floating raft system by combining the floating raft and semi-active control.The semi-active switch control of floating raft isolation system is studied in this paper.(1)The dynamic model of floating raft isolation system with single vibration source and non-rigid foundation is established.The expression of the evaluation indicators of the non-rigid foundation supported floating raft isolation system is deduced and characteristics of each evaluation indicators are discussed.The influence of foundation rigidity on the vibration isolation effect of floating raft isolation system is studied by using the evaluation indicators and the relationship between each evaluation indicators is analyzed.(2)The dynamic model of the semi-active switch control floating raft isolation system is established.Based on four existed switch algorithms,the characteristics of the semi-active switch control of the floating raft isolation system are discussed.The "elasticity adjustment algorithm 1" is proposed by which elasticity is adjusted and the "elastic energy adjustment algorithm 2" is proposed by which elasticity is adjusted and input energy is minimized.(3)The Simulink simulation model of semi-active switch control floating raft isolation system is constructed.The vibration isolation effect of floating raft isolation system under six kinds of switch algorithms are simulated and analyzed.The results show that the algorithms proposed in this paper is superior to the existing four algorithms,mainly in vicinity of the resonant frequency and the low frequency band which have greatest influence on vibration isolation effect.Among them,the elasticity adjustment algorithm 1 has the best vibration isolation effect in vicinity of the resonance frequency.The elastic energy adjustment algorithm 2 has the same vibration isolation effect in vicinity of the resonance frequency,but the vibration isolation effect is best in low frequency band.There is little difference in vibration isolation effect under the control of all algorithms in high frequency band.(4)A semi-active switch control floating raft isolation test system is built.The semi-active control floating raft isolation system vibration isolation system under six switch algorithms is tested.The results of the experimental analysis are basically consistent with the results of the simulation analysis,both of which show the new algorithms proposed of semi-active switch control of are more effective than the existing four algorithms,and the vibration isolation performance of floating raft isolation system can be further improved by the two algorithms proposed.