Mid Frequency Interioer Noise Of Vehicle Estimated Technical Research Based On Hybrid FE-SEA Method

As the vehicle’s most intuitive and most important performance of car driving experience,NVH(Noise,Vibration&Harshness)Was concerned gradually by the users and manufacturers,which was affected by mid-band noise level significantly.Therefore,the mid-band interior noise level must be controlled within a reasonable range.In order to meet the characteristics of deterministic and randomness of mid-band noise,the hybrid FE-SEA(Hybrid Finite Element-Statistical Energy Analysis Method)has been applied.When the hybrid FE-SEA method is used to model the vehicle,the prediction accuracy of the hybrid model is affected by many factors.The modeling efficiency is also related to many factors,and the influence of these factors on the precision and efficiency is often the opposite,which makes it difficult to balance accuracy and efficiency when the method is applied to the mid-band noise prediction.It exists the FE subsystem and SEA subsystem in the model and there is no strict definition of the standard of the sub-system division,which makes a lot of ambiguities in the modeling process.In order to solve the above problems and realize the effective application of the method in the prediction of mid-band frequency noise in the vehicle,based on a simplify small car and a vechile,the following research work is carried out through the accuracy of the model and the modeling process.(1)Based on the investigation of a large number of literatures at home and abroad,the basic theory of hybrid FE-SEA method and the response principle of deterministic subsystem and random subsystem in hybrid FE-SEA method are summarized in detail,and the preconditions and assumptions used in the hybrid FE-SEA method are listed.(2)The method of obtaining the input parameters of the model in the hybrid FE-SEA method is discussed.The modal density,the damping loss factor and the coupling loss factor of each subsystem are obtained by analytic calculation and numerical simulation.The sound absorption coefficient of the interior trim assembly of each position of the vehicle body was obtained,and the insertion loss of each interior trim was measured by the reverberation chamber-semi-chamber sound insulation measuring system.(3)In order to carry out the FE-SEA model verification,the force excitation and the vehicle noise response of the suspension under 60km/h sliding condition were obtained by road test.The tire noise excitation and its vehicle noise response were obtained at 60km/h constant speed.In order to verify the FE-SEA model of the simplify small car,the acoustic and vibration test was carried out under the condition of force excitation and acoustic excitation respectively,and the force excitation,acoustic excitation and noise response were obtained.(4)In order to improve the research efficiency,the hybrid FE-SEA model was established by using the simplify small car as the research object,and the validity of the hybrid model was verified by the acoustic and vibration test whose error is less than 3 dB(A).And then,the influence of the factors on the accuracy and the efficiency of the model in the case of force excitation and acoustic excitation is clarified.Combined with the acquisition of modeling parameters,the hybrid FE-SEA modeling process and the influence of each parameter on the accuracy and the efficiency of the model,the modeling rules of the hybrid FE-SEA model were established which used to guide the establishment of the vehicle FE-SEA model.(5)Based on the object vechile,applied the modeling rules of the hybrid FE-SEA model,the hybrid FE-SEA model was established.The establishment of FE-SEA model is discussed,including the division of subsystems,the establishment of co-node model,the creation of structural subsystems and the creation of acoustic subsystems,and the details of model processing in the model establishment process is clarified.The hybrid FE-SEA model was calibrated by combining the road test and the hub retract test,so that the model error was within 5dB(A).In this paper,the design of the acoustic packaging in the vehicle is changed.The innovation of subject:The two concerns about hybrid FE-SEA modeling are clarified,one is about the balance between precision and efficiency,and the other is model processing when vehicle is modeled.Based on the analysis of the factors influencing of the accuracy of the model,the influence of these factors on the efficiency of the modeling and the efficiency of the model solving is analyzed,and the hybrid FE-SEA modeling rules is developed which can be used to guide the establishment of the relevant model.The modeling process of the hybrid FE-SEA model is discussed in detail,and the modeling details of subsystems and model simplification are further clarified,and improved the rules which can provide guidance for solving similar problems.