Research And Improvement On Interior Noise Of Heavy Duty Commercial Vehicle Cab

With the development of commercial vehicle market in recent years,users have put forward higher requirements for improving the quality of the cab environment of commercial vehicles.Indoor noise which affects the comfort of cab is an important concern of users.Reducing cab noise can improve customer satisfaction,enhance product image and create great economic benefits for enterprises.This thesis was based on t the company's project of "the improvement of cab environment quality",the finite element model of a heavy commercial vehicle's white body was established,and the cab acoustic finite element model was established.Through sensitivity calculation and contribution analysis of cab structure and acoustic cavity coupling system,the main contribution parts of cab noises were found out,and the damping vibration reduction scheme is put forward.The whole Lane Road Noise test shows that the cab interior noise can be reduced by 1.6dB(A)at a constant speed of 80km/h.The main research contents were as follows:(1)The finite element models of the white body were created by using the finite element analysis software Hyper Works.The free modals of the white body model were calculated,and the modal frequencies and modes were analyzed,which provides a reference for the subsequent cab vibration isolation and noise reduction.(2)The finite element model of cab chamber was established in LMS Virtual.Lab software and coupled with the structure model.The acoustic sensitivity analysis of car body analysis was carried out.The result showed the peak frequency and acoustic pressure of the driver's right ear,which provides guidance for the subsequent analysis of cab chamber noise.(3)The whole white body are formed of the sheet panels,which enclose the cab's Indoor sound field,and the acoustic contribution of these panels was calculated.According to the analysis,we can find out the plates which contribute more than the others to the cab interior noise.The optimization scheme of the body panel damping was carried out with the vibration deformation of the plate in the cab structure response Then we calculated the acoustic sensitivity of the cab's finite element model,which had been updated with the damping optimization.It shows that the optimization of the damping can effectively reduce the cab interior noise.(4)The damping optimization scheme was implemented.Those vehicles used the damping optimization scheme had lower in interior noise,comparing the current vehicles.The noise insulation performance of the cab was improved significantly by the damping optimization.It is confirmed that the damping optimization scheme can be implemented in batches on the production prototype vehicle through test acceptance.This thesis established the cab structure and acoustic finite element model,acquired the optimization damping scheme of cab body panel based on the analysis methods of acoustical cavity sensitivity and plate contribution.The optimization scheme is identified effectively by the vehicle road noise test.The goal of reducing cab interior noise has been achieved,which can perform more positive impressions of the company.,and established a standard process of the cab interior noise optimization In addition,it has a great reference value for noise reduction of cab structure on other platforms.