Simulation and test methods on NVH performance of axle system 2024-01-2950

For electric vehicles, road noise, together with wind noise, is the most important contributor for vehicle interior noise. Road noise is very dependent on the NVH behavior of axle system including wheels and tires. Axle system is part of vehicle platform which should be compatible with different body variants. Therefore, il is important to characterize the NVH performance of an axle system independently of car body structure, so that the design the axle can be optimized at the early stage according to the global requirements of all the related vehicles. The best way to characterize the NVH performance of an axle system is to measure the blocked forces on an appropriate test rig. However, the measurement of blocked forces from an axle system requires very stiff boundary conditions which is difficult to achieve in practice. For axles with rigid mountings, it is nearly impossible to measure the blocked forces on test rig. Due to the presence of numerous joints and metallic structures, the NVH behaviour of an axle system is very complex. This article presents an efficient method for characterizing the NVH performance of an axle system by means of measurements on a test rig combined with simulation in rig condition. By installing a full axle system on a standard test rig with realistic mounting brackets, the output forces from the axle at all the connection points with car body can be easily measured. These forces are dependent on the boundary conditions. In parallel, simulations are carried out with FE models including not only the axle system but also the test rig and the mounting brackets. Then, the necessary recalibration is made on the simulation models by correlation between simulation and measurement. Using the recalibrated models, the blocked forces of the axle system can be easily calculated by setting infinitely stiff boundary conditions. This hybrid method allows to obtain the blocked forces from the axle system by using a standard test rig without the need to build expensive new rigs. In addition, this method allows to have a clear understanding on the coupling phenomena between an axle system and the car body structures.