Research On Vibration Characteristics Of A Large LNG Ship

With the social progress and the rapidly increasing demand for energy, natural gas asa new type clean energy has been widely used. The market for LNG(liquefied naturalgas)ships demand increases significantly. Because of different excitations in ship sailing, itwould give rise to resonance and severe vibration to affect normal voyage of a ship andharm to human health.Therefore, the analysis on global vibration characteristics of large LNG ships isnecessary. Vibration characteristics of160000m3LNG ship have been studied in thispaper.Firstly, the finite element software MSC.PATRAN has been used to simulate160000m3LNG ship. The global vibration of the finite element model under two conditions,which are full load and ballast, has been analyzed in the use of software MSC.NASTRAN.The natural frequencies and mode shapes of the ship have been calculated. Meanwhile thevibration response under propeller excitation has been analyzed and checked inaccordance with the relevant specifications.Secondly, the structural acoustic radiation characteristics of the ship stern have beenstudied with the boundary software SYSNOISE. The sound and near-field sound pressurelevel of the stern have been analyzed in coupled finite element and boundary elementmethod.Finally, the method used to reduce the vibration of the ship stern in mid-highfrequencies has been explored with software VAONE based on statistical energy analysis(SEA). Simultaneously, the effect on vibration isolation performance by several isolationsystem parameters has been discussed.Through the analysis of160000m3LNG ship, the vibration characteristics of largevessels have been in-depth understood. The calculation results in this paper provide areference to the design and construction of similar ships.