Research On Automobile NVH Performance Based On Suspension System

The NVH technology of automobiles is one of the core technologies inautomobiles’ research and design, the performance of the NVH will influence theproduction and sale in a great degree. There are many factors that influence thevibration and noise, when a car runs at an intermediate speed and a low frequency, theinteraction of the wheels and road will be the main source of vehicle interior noise andvibration. The excitations from uneven road lead to vibration of wheels. The vibrationof the wheels reaches to body after the buffering and absorbent by the suspensionsystem, lead to vibration and interior noise of the body.Based on the study on the relationship of suspension system and NVHperformance, the rigid-flexible coupled multi-body model of the suspension systemand the fluid-solid coupled FEA model of the body were built. Through the analysis ofthe key point force in the multi-body model and the transfer function in the FEAmodel, the vibration and noise environment was predicted and improved by someways.The main contents of this paper are as follows:First, the multi-body dynamic model of suspension system was built throughADAMS/Car after achieving the basic parameters of the vehicle. The front suspensionof the sample vehicle is Macpherson while the rear suspension is Twist-beam style.The model would have to consider the impact of elastic deformation of the twistbeam．After building the model, its kinematics analysis was run and evaluated throughthe parallel wheel travel experiment, including the change of toe angle, camber angle,kingpin inclination angle, caster angle and caster moment arm with the wheel t ravel.Second, the other subsystems, such as the steering system, stabilizer bar, tiressystem, brake system, body and so on, are also built in ADAMS/Car software. Theyare assembled together with the suspensions to compose a whole multi-body model.The flexible deformation of the stabilizer bar was also considered．A stochastic roadwas created based on PSD function to simulate vehicle riding. The force curves intime domain of the key points which link body and chassis were achieved. Transformthese curves into force curves in frequency domain, including magnitude and phase.Third, the FEM models of trimbody and acoustic cavity were built throughHyperMesh and LMS Visual lab. And their modals were analyzed. Calculate the vibrate transfer function and noise transfer function of three directions (X, Y and Z) ofthe key point with MD Nastran, including magnitude and phase.Finally, the force curves were multiplied by transfer function to get the realvibration and interior noise conditions. The vibration and interior noise environmentwas analyzed and improved by acoustic participation factor and free dampingtreatment.