Research On Vibration And Noise Characteristics And Damping Structure Optimization For Ship Thin-Walled Gearbox Housing

As the power transmission device of the warship,the vibration and noise level of the gearbox is not only related to the comfort of the cabin environment,but also has an important impact on the concealment of the warship.The gearbox housing is the main transmission of vibration and noise of gearbox.Under the action of multi-frequency excitation,the housing transmits vibration to the hull through its feet,and its wall radiates noise.Therefore,it is of great significance to reduce the vibration and noise of the gearbox.In this paper,the vibration and noise characteristics of a large thin-walled gearbox housing used in warships are analyzed,and the influence of damping composite structure on the vibration reduction effect is studied and applied to the housing to achieve the purpose of vibration and noise reduction.The finite element model of the gearbox housing was established,and the modal analysis and harmonious response analysis were carried out.The housing mainly presents a series of plate and shell bending modes at the thin-walled structure.The vibration acceleration response within 1000 Hz of the key measuring points in the bolt connection area and the thin-walled surface area of the housing is analyzed,and the measuring point with larger vibration is determined.Using the vibration acceleration of the housing surface as the acoustic boundary condition,the radiated noise of the housing is calculated by the FEM/BEM method.The radiated sound power spectrum curve of sound field,the sound pressure level nephogram of radiated sound field at each main frequency and the sound pressure level spectrum curve of typical measuring points of sound field are obtained and analyzed.The cabinet panels were divided,and the acoustic contribution was analyzed at the 3 frequency peaks with higher radiation noise.The 6 panels with higher contributions were selected as the key areas for subsequent vibration and noise reduction.The housing panels were divided,and the acoustic contribution was analyzed at the 3 frequency peaks with higher radiation noise.The 6 panels with higher contributions were selected as the key areas for subsequent vibration and noise reduction.Based on the modal strain energy method,a simulation analysis model of the damped composite structure was established.The influence of damping material characteristic parameters such as storage modulus and Poisson’s ratio on the vibration damping effect of the structure is studied.The influence of the thickness of the damping layer and the thickness of the constraining layer on the vibration reduction effect of the structure is studied,and it is found that the thickness of the constraining layer has an optimal value range.The different laying schemes were compared,and the damping laying based on the analysis results of the acoustic contribution was determined.Based on the central combination test design and the RSM method,the response surface models of the 1^st,3^rd,5^th and 7^th modal structural loss factors with respect to the thickness parameters of the damping layer and the constraining layer are established.According to the response surface model,the optimization design is carried out,the maximum loss factor of each order is taken as the goal,and the additional mass limit of the structure is the constraint condition,and the optimized damping layer and constraining layer thickness are obtained.Applying it to all the structural panels with a large contribution to the gearbox housing,comparing and analyzing the vibration and noise reduction effects of the composite housing structure before and after optimization,the total sound power level is reduced by 11.62d B,and the average acceleration level peak value is reduced by 18.45d B.