Investigation and refinement of gearbox whine noise

Structure borne noises can be transmitted to interior cabin via physical connections by gearbox as well as other active components. Experimental Transfer Path Analysis (TPA) methods are utilized to investigate main paths of vibrations which are eventually perceived as noise components inside the cabin. In this study, contribution ranking of transmission paths from active system components through the physical connections into the interior cabin are investigated by Operational Path Analysis with Exogenous Inputs (OPAX) method. In addition, the sensitivity and rigidity characterization of the body through dominant paths according to OPAX were measured to reveal the reason for the whine noise to the inner cabin because of the operational forces generated in the dominant structure-borne paths. And also, operational modal analysis was carried out to examine the modes of the dominant path components. The modifications are applied on dominant transfer paths according to dominant paths characterization by operational deflection shape analyses. Thus, the root causes are investigated on vehicle level NVH tests while observing the variations in the interior cabin noise level.