The Acoustic Vibration Characteristics Analysis On The Structuer Of Reducer Shell For Ship

The acoustic vibration characteristic is one of important performance targets for reducer shell. The vibration of reducer is a key vibration sources for ship. It not only produces big radiation noise and the vibration wave can pass to the entire ship from base hull, and causes local area resonance and affects the normal work of the instrument, but also affects the daily life of crew. The vibration of reducer shell is mainly vibration for the reducer. So the acoustic vibration characteristics analysis on the structure of reducer shell is very important for the control of noise and vibration.This article start from the vibration of reducer shell, deeply to the radiation noise that caused by the vibration. It analyses the vibration characteristics of the reducer shell on the base of FEM and the method of Block Lanczos. In this way,it provides good research foundation for the vibration damping and noise reduction. Based on the reducer shell modal characteristics, the spectral analysis of the entire system has been made. The incentive load is random white noise which spectral range is from 0 to 2000Hz. Only in this condition, the imitate load can approach the truth load. By modal superposition method, the vibration acceleration level response of the key parts place for reducer shell is calculated. According to the spectrum diagram, the key parts of vibration response characteristics could be identified. It not only provides boundary conditions for subsequent acoustic analysis but also provides design direction for the structure improvement.Based on analyzing the vibration property of reducer shell, the acoustic boundary conditions have already been determined. The radiation sound power of reducer shell in the sound field has been determined from 1 to 1000Hz. Being based on the acoustic resonance coupling theory, the distribution sound pressure and acoustic level response in typical area are calculated in one meter outside the shell in the use of the theory of coupled vibro-acoustic. At the same time, the size of the acoustic radiation is forecasted under incentive load of random white noise. It provides good research foundation for the vibration damping and noise reduction.In order to study the damping influence of vibration more fully. In this paper the damp is added for the finite element model of reducer shell structure. Through the research of laying constrained damping layer on shell surface and pouring damping into the inner of the shell. The influence of damping for vibration characteristics of reducer shell can be figured out.Because the reducer shell has a lot of for structure cavities, the main vibration reduction method is to perfuse damping actually. So the narrow proportion experiment model is established, its theory and test frequency response function have been calculated from FEM and test method to get its perfusion damping characteristics. It can provide some reference value for the whole reducer shell structure after studies. Based on the above results, in addition to adding damping and perfusion damping, this paper put forward some structure optimization plans, and acoustical enclosure is designed for the reducer shell.