A methodology for evaluating the structure-borne road noise prior to a prototype vehicle using direct force measured on a suspension rig

Numerous previous studies have been conducted on quantifying road noise through transfer path analysis (TPA) using the matrix inversion and the dynamic stiffness methods. However, the matrix inversion method is a calculation that always contains error, even when treated with the best condition number found by trial and error iteration to match the calculation SPL (sound pressure level) to measured SPL. Furthermore, the caveat of the dynamic stiffness method is that it requires accurate dynamic stiffness value up to the frequency range of interest, which, in reality, is rarely available and is challenging to obtain. Therefore, TPA using these two methods is only possible when a complete vehicle is available. For the sake of cost and time reduction, circumventing these limitations is crucial within the vehicle production period. The main focus of the present study is to directly obtain the operational forces at the suspension mounting points neglecting the effect of the vehicle body through a special suspension rig. The suspension rig is verified through a comparative analysis with the actual baseline vehicle measurement up to 250 Hz. In addition, an example approach for finding suspension's NVH performance improving factor using the rig bench-marking technique is introduced. (C) 2016 Institute of Noise Control Engineering.