Modeling And Vibration Characteristics Analysis Of Floating Raft Vibration Isolation System Of Marine Diesel Generator Set

Vibration and noise caused by the operation of marine diesel generator set can reduce the reliability of mechanical equipment, thus the instrument and meter can’t perform normally. Both the passengers and seafarer may be influenced mentally and physically. Warship and yacht have strict requirements to the vibration isolation, so the traditional single vibration isolation system can’t fulfill the requirement of vibration isolation. Floating raft vibration isolation system has many advantages, for example, vibration isolation effect is well, arrangement is flexible and it can save space and so on. Floating raft vibration isolation system has been applied to the yacht and warship repeatedly. Now the design of vibration isolation of marine diesel generator set is taken as an example to testify the quality of vibration isolation by analyzing the vibration characteristics through the establishment of floating raft vibration isolation system’s finite element model of the marine diesel generator set.According to the theory of vibration isolation, upper and lower vibration isolator’s stiffness and damping of the floating raft vibration isolation system are calculated. Floating raft vibration isolation system’s finite element model of the marine diesel generator set is established in the ANSYS. The effect that the quality of floating rafts to vibration isolation effect is analyzed. Four floating raft vibration isolation systems of different floating raft mass are applied to the analysis of constraint modal analysis. Four floating raft vibration isolation systems of floating raft with different mass are applied to the analysis of free modal. Modal analyses are compared and the fittest floating raft is determined. Then harmonic analysis is applied to the floating raft vibration isolation system and the resonance rate of the y direction is determined. The influence of on structural damping vibration isolation system is analyzed. The result of the harmonic analysis shows that the y direction’s resonance frequency of the whole system is7Hz. The whole system’s structural damping can reduce vibration apparently next to the resonance frequency but has a little influence on vibration far from the resonance frequency. Finally, the vibration isolation efficiency of the floating raft vibration isolation system is compared to that of the single vibration isolation system, finite element model of the single vibration isolation system is established and the exciting force produced by the marine diesel generator set when it operates has been calculated. Single vibration isolation system and floating raft vibration isolation system applied to the transient analysis in seven conditions. The result shows that vibration isolation efficiency of the floating raft vibration isolation system is much better than that of the single vibration isolation system under the seven conditions.The vibration characteristics analysis indicated that the floating raft vibration isolation system of marine diesel generator set established in this paper has a good vibration isolation effect. It can provide reference for floating raft vibration isolation system’s design.