Analysis And Optimization Of Vehicle Vibration And Noise Considering Vibration Isolation Elements

Intelligent driving and new energy are two new technologies in the development of the automotive industry today,but no matter how intelligent and energy efficient the vehicle becomes,its mechanical quality is always an important criterion for judging whether a car is good or not.In the early stage of vehicle development,it is basically impossible to realize the NVH performance test of the whole vehicle,and the use of virtual simulation means can realize the vibration and noise prediction of the vehicle in the early stage of development,which greatly shortens the development cycle and reduces the costs.However,due to the existence of such nonlinear vibration isolation elements as rubber bushings in the chassis,and the vehicle Virtual Transfer Path Analysis is based on a linear system to achieve,which leads to the acquisition of vibration and noise response has no reference value,then the diagnostic analysis based on such response results are meaningless.In order to solve such problems,this paper first carried out the equivalent linearization of rubber bushings in the chassis under specific operating conditions to improve the accuracy of the prediction results,and then suppressed the vibration noise response at response points through various diagnostic methods,and the research methods are as follows.(1)Finite element modeling of the body-in-white and other subsystems was carried out,and the reliability of the body-in-white simulation model was verified by aligning the calculated body-in-white modes with the experimental modes,and the cavity model was established and briefly analyzed.The nonlinear solutions for the front and rear bushings of the control arms in the front Mac Pherson suspension and the longitudinal arm bushings in the rear torsion beam suspension were carried out to obtain the corresponding forces and moments,and the corresponding equivalent stiffness values were calculated by combining the respective nonlinear stiffness curves.(2)Road excitation was applied using the wheel center as the excitation point,and the frequency response prediction was performed based on the obtained equivalent stiffness for the vibration of the main driver seat mounting point,the 3 point of steering wheel and the noise of the main driver and right rear passenger outer ear side.The Virtual Transfer Path Analysis was performed on the whole vehicle,and the frequency domain response curves of each vibration and noise were compared with the response curves obtained by the frequency response method to verify the reliability of the Virtual Transfer Path Analysis,and it was found that the vibration acceleration amplitudes of the right front,left rear and right rear side mounting points Z-direction of the seat and X-direction of the 3 point of the steering wheel at 63 Hz were too large,and the sound pressure level on the outer ear side of the main driver exceeded the critical value at 153 Hz,and the corresponding path contribution results.(3)The Input Point Inertance for the large contribution path identified by the Virtual Transfer Path Analysis determined that the dynamic stiffness of the upper attachment points of the left and right sides of the rear suspension damper did not reach the target value at 63 Hz,and the excessive response of the vibration response points was caused by the weak dynamic stiffness of these two attachment points,and combined with the Operational Deflection Shape and Modal Strain Energy Analysis to determine the problematic components that caused the insufficient dynamic stiffness of the two attachment points.The Modal Contribution Analysis method was used to determine the maximum positive contribution of the 35 th order modal at 153 Hz,where the amplitude was excessive due to the local modal at the inner door panel.(4)Taking into account the body crash safety and vehicle weight,the thickness of the problematic parts was improved using sensitivity analysis,and damping sheets were added to the inner door panels based on the damping control strategy,while ensuring that the body-in-white bending and torsional stiffness were not adversely affected.The optimized structure resulted in a weight reduction of 0.4 kg compared to the model before structural optimization and a significant reduction in vibration and noise response.