Vibration Analysis And Cabin Noise Prediction Of A Deck Carrier Ship

Levels of ship vibration and noise are important indicators of shipbuilding quality.In the case of ship with poor vibration and noise,not only will the structures and equipment on board be easily damaged,but also the health of the crew or passengers will be negatively affected.With the improvement of people's living standards,comfortable living and working environment on ship is becoming more and more important.Therefore,it is necessary to predict the levels of vibration and cabin noise at the design stage in order to optimize design for the problem areas.As computer technology progressing,the adoption of simulation software for prediction and optimization has become an effective and accurate method.This paper takes a 3,000-ton deck carrier ship as the research object.According to the structure plan,using MSC.Patran software and based on the finite element method,a three-dimensional finite element model of the ship is established.Then the ship mass models under full-load departure and ballast arrival conditions are established according to loading condition manual.Importing the models into MSC.Nastran,the ship natural frequencies of overall vibration under two working conditions are calculated and the frequency reserve is evaluated according to the CCS Guidelines for Shipboard Vibration Control.Applying the propeller pulsation pressure to the FE model as the excitation force,the forced vibration response values are calculated under two conditions.Analyzing the acceleration response values and velocity response values of the key positions in the superstructure,the results are evaluated according to ISO 6954-1984 Guidelines.Except for ballast condition,selection points on the compass deck slightly exceed the lower limit of the Guidelines,and all the other points meet the requirements.However,from the point of view of habitability,small vibration on the compass deck will not cause harm,so the vibration characteristics of the ship are good.The three-dimensional FE model is imported into VA One software.Based on the Statistical Energy Analysis(SEA)method,a SEA model is established for the deck carrier ship.Air noise & structure noise of main engine,Air noise & structure noise of auxiliary engine and propeller structure noise are chosen as excitation source and then noise is predicted in representative superstructure cabins.Comparing the forecast results with the criterion values,it is found that the forecast values exceeded the criterion.The accuracy of the model is verified by comparing the forecast and measured values.Each excitation source is applied respectively and the composition of noise in each representative cabin is analyzed.Sound insulation control technology is used to optimize the design and noise is predicted in the representative cabins by VA One software.The results show that the sound insulation optimization scheme can significantly reduce the noise level of the representative cabins,but it is not yet up to the criterion.So the vibration isolation control technology is further adopted to optimize the design and the result shows it can achieve a good control effect.This paper forecasts and analyzes ship vibration and cabin noise from the perspective of habitability,and uses simulation technology to discuss the optimal design of cabin noise.The aim is to provide methods for assessing the habitability during the ship design phase,and to provide reference for optimal design and simulation of ship cabin noise.