Study On SEA Analysis And Reduction Of Vehicle Interior Noise Based On Test Calibration Method

Vehicle NVH performance is gradually attracting more attentions from researchers,manufacturers and customers,and it somehow indicates the quality of automobile products with the increasing pressure from the market and customer requirements.The mid-high frequency interior noise can get control through the sound package design and optimization.While the statistical energy analysis method(SEA)can effectively solve this problem and now have developed into the main method for the sound package development.Because lack of the effective method to correct model and select the typical working conditions,there is a big deviation between the simulation result and the test result when using the SEA method for sound package design and optimization.Therefore,combined with the domestic research and engineering application,a test correction SEA method is proposed.The main input parameters are obtained from the tests to improve the predictive accuracy and structural equivalence method based on the modal coordinate is used to improve the model correct efficiency.Meanwhile,the typical working conditions are determined by the method of combing the objective test and subjective evaluation.Based on a domestically made passenger car,the method is carried out to make a systemic analysis and verification.The main contents of this paper are listed as follows:(1)In order to improve the predictive accuracy,A set of test correction method for modal density,CLF and DLF is proposed.Different from previous numerical method,the modal density is obtained through average input conductance and the DLF,CLF through multiple point input conductance,which helps us solve the noise prediction accuracy,especially the CDLF method application on analysis of the complex structures,which studies and verifies the strong coupling relationship between subsystems.(2)A research approach of equivalent structure theory based on the modal coordinate has been studied to analyze the effective application on vehicle SEA noise analysis to improve the model correct efficiency on the ideal condition..From the view of modal density,the physical coordinate of dynamics equation is converted to modal coordinate.The transmission loss calculated from the main path of reduce vehicle SEA model is equivalent to the complex through the modal radiation theory.The model correct efficiency gets improved because of the equivalent simplified model.(3)For determining typical noise analysis conditions,a strategy has been devised based on the objective test and subjective evaluation.Based on the noise source identification,the main research conditions,the data of sound pressure level of the body and interior are measured.Considering the objective tests may not fully reflect the typical noise conditions and the subjective feeling of passengers,subjective evaluation based on the psychoacoustic parameter is proposed to determine the typical working conditions for vehicle SEA analysis,which provides a comprehensive proof for the interior sound quality control.(4)For the control of the interior noise of a domestically made passenger SUV car,a strategy has been devised,aimed to satisfy the requirements of vehicle performance.This tragedy gets an accurate and valid SEA model by the benchmarking between the ideal conditions and operation conditions.Based on the energy power of noise transmission path,the main transmission path in different frequency bands and the contribution of noise source are obtained.By adjusting the thickness of the weak area in firewall,improving the transmission loss of passthrough and adding the cotton in energy,the sound pressure level of interior noise have meet the performance requirement of vehicle.It has proved through the tests that the sound pressure level at driver's head cavity and rear right passenger's head cavity respectively decreases about 2.0dB and 1.7dB under 3 gear WOT condition and decreases 1.4dB and 1.1dB under 1 gear 2500r/min condition.Based on the SEA method and in order to improve the predictive accuracy,model correct efficiency and typical conditions,a systemic method of sound package design and optimization are researched.Finally,based on the power flow,the noise transmission path and the contribution of the source are determined.Above these analysis,it develops a comprehensive strategy for vehicle sound package,which contains SEA model building,basic parameters correction,conditions determination and plans optimization.