Research On Noise Reduction Of Driver’s Cab For Diesel Locomotive Based On Vibration And Noise Analysis

With the development of technology,railway rolling stock were replaced by electric locomotives for passenger transport,but diesel locomotives were active in freight and dispatch.Due to the working mechanism of diesel engine itself,there was generally excessive noise for rolling stock.Continuous noise inside the rolling stock would damage the auditory system of workers inside the locomotive,and seriously affected their physical and mental health.The noise outside the locomotive would greatly disturb the lives of residents along the railway.Therefore,it was of great significance to do research on the noise reduction of diesel locomotives.Generally,the research and measures on noise reduction for rolling stock were based on noise prediction of the sound field response simulation and statistical energy analysis(SEA)of geometric models.However,due to the effect of factors such as grid defects,model simplification schemes,and computational complexity,some problems couldn’t be simulated very finely in the simulation stage,resulting in the problem that the locomotives generally still had large noise after the assembly was completed.During the period from the noise type test to the delivery of the vehicle,there was no systematic method for effectively diagnosing and resolving problems at this stage,which would bring manufacturers troubles and high improvement costs.Based on the above problems,the diesel locomotive for dispatch was studied by establishing a noise and vibration test system.In the test,synchronous signals were added as a reference for data synchronization and interception among different data acquisition systems.One-third octave spectrum was applied to make a basic assessment of the noise environment in the vehicle for knowing sound pressure level distribution and spectral structure characteristics of measure points of each room.Operational Deflection Shape(ODS)was applied to find the area with large deformation in the vehicle structure,then fast spectral kurtosis was applied to filter for obtaining a high SNR signal,so that the feature frequency was clearly located to find the structural noise source associated with it.According to the results of operational modal analysis of vibration,it was determined that the modal response of the entire vehicle structure was not excited,and the structural vibration that contributed mainly to the cab noise came from the local factor.Improvement plans for the source of structural noise were proposed,and sound insulation and sound absorption measures were proposed for those key frequency bands of air-borne noise.After the completion of all improvements,tested and verified that the noise inside the rolling stock was reduced by an average of 12.4 d B(A)owning to joint measures of reducing the structural noise and airborne noise.The results of the improvement were confirmed satisfactory and they could be used as a core part of improvements for the successor to the diesel locomotive.