Vehicle Interior Low-Frequency Acoustic Performance Optimization Based On Transfer Path Analysis

The level of interior noise directly affects the ride comfort of drivers and passengers.How to quickly diagnose the root causes of noise problems in the early stage and strive to solve noise problems in the design stage is particularly important.Aiming at the lowfrequency noise response of the vehicle,the finite element model of the vehicle including the body and chassis was established by using the finite element method.The virtual transmission path analysis of the vehicle interior noise under idle and constant speed conditions is carried out.The vehicle interior noise is suppressed by body damping topology optimization,bushing stiffness optimization and working deformation analysis.The finite element model of the body-in-white was established by Hyper Mesh,and the free modal of the body-in-white was analyzed by Opti Struct.Then the free modal of the body-in-white was tested by using the experimental equipment such as exciter and acceleration sensor,and the experimental modal data were obtained to verify the accuracy of the finite element model of the body-in-white.On the basis of this model,the acoustic cavity model,the acoustic-solid coupling model of the interior body and the chassis finite element model were established,and the finite element model of the whole vehicle was established,which lays the foundation for the simulation analysis of the interior noise of the subsequent working conditions.For the analysis of interior noise under idling condition,the acoustic-structure coupling finite element model of the interior body was used to load the measured vibration acceleration signal under idling condition at the excitation position of the body,and the interior noise response was calculated,which is in good agreement with the experimental results.The transfer function of the body system excited to the response position was obtained by the finite element model.The transfer path analysis model was established by combining the vibration acceleration excitation and the transfer function of the simulation under the actual working condition.The acoustic noise contribution of each path at 121 Hz frequency of the driver’s right ear position under idle condition is analyzed.The path with larger contribution is selected as the excitation position of the panel contribution analysis.Combined with the results of the panel contribution analysis,it is determined that the rear floor is the target plate for laying damping materials.Through topology optimization analysis,the optimal layout of damping material in the rear floor area is obtained,which reduces the laying quality of 1.2 kg damping and reduces the sound pressure level of the driver’s right ear at 121 Hz under idle condition by 5.59 d B(A),and effectively suppresses the interior noise under idle condition.For the vehicle interior noise when the road noise condition is 60 km/h and the speed is constant,according to the vibration acceleration signal at the four wheel steering joints measured on the rough road,the transfer function from the wheel center to the reference point of the steering joint was calculated by using the finite element model.The wheel center force excitation was extracted according to the inverse matrix method,and the wheel center force excitation was loaded into the finite element model of the vehicle to obtain the simulation results of the vehicle interior noise,and the correctness is verified by comparing the test results.The virtual transmission path is used to analyze the road noise problem points,and the contribution analysis is carried out for the peak values of60 Hz and 99 Hz.The bushing stiffness at the connection position with large contribution is optimized.The sound pressure level of the driver’ s right ear at 99 Hz is reduced by1.22 d B(A),and the sound pressure level of the driver’ s right ear at 60 Hz is reduced by0.99 d B(A).Due to the obvious peak at 99 Hz of transfer function,the vibration at the door and rear cover is found to be large through the analysis of working deformation.After the reinforcement plate is added on the plate,the sound pressure level of the driver’s right ear decreases by 2.3 d B(A),which can improve the interior noise problem.