Effects of double bottom tank and contained oil on the vibration transfer characteristic of main engine

The integrated model of main engine and double bottom tank underneath the main engine was developed to study the effects of double bottom tank system on the vibration characteristic of the main engine,which would improve the actuation of vibration isolation for main engine.Based on the finite element method,this model focused on the shift of system vibration frequency and the influence of oil on the system vibration responses.Simulation results indicate that the system eigenfrequency decreases as the double bottom tank is put into consideration.And the first eigenfrequency rise a little when the oil is filled,while the other higher frequencies decrease.Due to this effect,the frequency response curve moves towards the higher frequency,and the peak value of the response at original resonance frequency drops by more than 80%.