A Study on the Ship Vibration Analysis of Ocean Research Vessel Using Electric Propulsion

Abstract

With ships tending to the direction of large-scale and high-speed, people pay more and more attentions on the vibration, impact and noise. Because of the exciting forces caused by periodic unbalance force of the internal machine and propeller, it will inevitably produce the vibration. And when the exciting frequency is equal or close to the natural frequency of the ship, the overall resonance phenomenon will occur and the amplitude will reach its maximum value. Even if the resonance will not badly occurred, due to the frequency overlap, the factors of hull plate such as vibration displacement and acceleration will become bigger than before. It will make a serious influence on ship structure and comfort for crews and so on. In order to avoid these types of things happen, it should control and solve the problem of vibration and noise on the ship, especially for the resonance. Therefore，the vibration analysis of full ship is more important even necessary in the stage of design and production. In order to avoid the damage of ship structure and the discomfort of the crews cased by the overall resonance of the ship, the ISO (International Standard Organized) made some vibration evaluation rules for ships and the other structures. The ISO 6954-2000 (E) was consulted in this paper for the vibration analysis, which is used in the most of the classifications and research institute. The objective of this paper is to study on the hull vibration of special purposes vessel using electric propulsion. And it uses the finite element method of the three dimensional model to analysis the vibration characteristic on DWT 1,000 ton class ocean research vessel. And then the results would be compared with the results by empirical formula to analyze the causes of the differences. In addition, compared with the normal diesel engine, the response of the electric propulsion would be lesser. It has also been researched how much the specific decrement of the vibration responses are. Through the above research, the result of this paper also may provide an important reference data to the other researchers in the same field.