Development Of Integrated Assessment Software Of Ship Vibration And Cabin Noise

As an important design technology to improve the performance of ships,the vibration and noise reduction is always a hot and difficult point in the field of ship design.For the evaluation of vibration and noise,the International Organization for Standardization(ISO),the International Maritime Organization(IMO)and ship classification society of many countries have developed common standards,based on which countries respectively formulate restriction for sound pressure level,sound power level and comfort level in different ship hull position according to their specific requirement of vibration level and noise level.With the rapid development of computer application technology,functions provided by a single program cannot usually meet the requirements and manual calculation is required,which is complex and time-consuming,so demand of the integrated of ship vibration and cabin noise evaluation software is increasingly obvious.There is no automated assessment software at home and abroad.Firstly the ship vibration and noise evaluation criteria of the International Standardization Organization,the International Maritime Organization and the world's major classification society is summarized for the follow-up study as a reference.Secondly,based on the evaluation criteria and the theoretical basis of the research,this paper develops an integrated evaluation software for ship vibration and cabin noise.Thirdly,the direct vibration sources of the ship include three main types: main engine,propeller and wave load.The methods for reducing structure vibration in response to these sources are the damping technology,dynamic mechanical vibration isolation,vibration absorption etc.Among them,the floating raft(base)vibration isolation technology is adopted as the most present and effective vibration isolation method.In the analysis of dynamic response of ship structure using this kind of vibration isolation technology,equipment dynamic load is transmitted to the hull plate frame through the base,which forms the equipment-base system.Because the exciting force is difficult to measure,yet the acceleration transferred to the base plate of the device is easy to measure,so the research about relevant model-building method and the ship dynamic response equivalence of applying these two kinds of load is of high application value for real project.This paper studies the influence of dynamic load on the modeling method of ship equipment-base system in the dynamic response of ship structure.Based on theoretical derivation,the influence of these two kinds of dynamic load on the way of building models is analyzed in the particle vibration system.Then,two FE models of a specific hull of a real ship is built to confirm the validity of the conclusion by comparing the acceleration level of the check points in these two FE models,one of which is an equipment-base model loaded with exciting force and the other is a single base model loaded with acceleration.The research shows that,in low frequency domain,when the type of dynamic load on the “Equipment-Base System” is acceleration,there's no need to build equipment or consider its mass in the FE model.Finally,the reliability and efficiency of the software are verified by the example of real ship vibration and acoustic design.Through this article,we can understand the method and process of evaluation of ship vibration and noise,know the differences of ship vibration and noise evaluation standard among different society and international organizations and also clearly understand the purpose and method of using the ship vibration and noise evaluation integrated software.