Analysis & Control Of Vehicle Interior Structural-borne Noise Excited By Engine

The vehicle interior noise has im pact on the health of the occupants,and its level is not only limited by laws and regulations,but also affects market competitiveness of the vehicle.So the research to reduce the vehicle interior noise is of great significance.To seek out an ef fective method to reduce the structure-borne interior noise,this paper set a SUV car(a newly designed vehicle)as the research object,and through the mechanism of structure-borne interior noi se generation,analyzed and controlled the transfer path of vibration,which is cause d by engine excitation.The m ain research contents include:Powertrain mounting system analysis and optimization: Powertrain mounting system model with six degrees of freedom is built and its analys is program based on GUI of Matlab is programmed;the program is used to analyze natural frequencies and modal decoupling rates of newly design ve hicle's powertrain m ounting system;the energy uncoupling m ethod and the genetic algorithm are applied to optim ize the powertrain mounting system by taking the reasonable allocation of the natural frequencies as an objective,taking the stif fnesses of mounts as design variables and taking the decoupling rate of the mounting system as a constraint;finally,got a powertrain mounting system with a good decoupling feature and a reasonable allocation of the natural frequencies.Vehicle body structure modal an alysis: The finite elem ent(FE)model of competitive vehicle body-in-white(BIW)is built,com pared the free modal analysis results with the modal test results of the competitive vehicle BIW,the analysis results are fit to the m odal test data well;after verify the reliabi lity of the m ethod of finite element modeling,the FE modal of the newly designed vehicle BI W and trimmed body are built through this method.Powertrain mounting point dynam ic stiffness analysis: Modal superposition method is used to obtain the input point inertance(IPI)of the powertrain mounting points;and the newly designed vehicle powertrain mounting point dynamic stiffness is proved to meet the engineering requirements,after comparison IPI results between the competitive vehicle and the newly designed vehicle.Vehicle interior acoustic analysis: Interior acoustic cavity FE model of the newly designed vehicle is established base d on trimm ed body and free acoustic m odal analysis is launched to analyze th e acoustic characteristics;A coupling model of the body FE model and the cavity FE m odal is created,based on modal frequency response analysis m ethod,the noise response characteristic of the interior noise reference point is analyzed by applying a unit harm onic load on the powertrain mounting points respectively.Structure optimization: Panel participation factor(PPF)and m odal participation factor(MPF)analysis are used to analyze the vehicle interior noise peak response,and according to the analy sis results,some comprehensive methods are present,whic h include local structure improvement,posting damping pieces on the sensitive position and replacing the front windshield with PMMA-PVB glass.The results show that the optimized measures can reduce the respondent sound pressure peak of the interior reference point which located in driver's right ear position effectively.