Transfer path analysis of rumbling noise in a passenger car based on in-situ blocked force measurement

Abstract This paper presents the In-Situ blocked force transfer path analysis (BF-TPA) to identify the structure-borne path of rumbling noise in vehicle cabin. The control of rumbling noise is one of the major strategic targets of interior sound quality inside the cabin of a passenger car. To effectively control rumbling noise in a passenger car, the transfer path of the rumbling noise should be initially identified. It is known that the major source of this noise is the combustion force of an engine. The combustion force excites the engine and induces vibrations of the powertrain. These vibrations are then transferred to the body of the vehicle via its structural transfer path. Moreover, the vibrations of the vehicle’s body emit internal vibra-acoustic noise. This noise is often referred to as the rumbling noise due to the structural borne path. If there are structural resonances among the structural paths such as the engine, transmission, mount bracket, suspension, and the vehicle’s body, the rumbling noise could be amplified. To identify the major resonances of the structural transfer path, classical transfer path analysis (CTPA) has been traditionally utilized. The method has a significant limitation in that it is necessary to decouple the substructures to obtain the contact force between individual components and to identify the transfer path of the structure-borne sound. Recently, In-Situ BF-TPA was introduced and this approach does not require the decoupling of the substructures. In this study, we identify the structure-borne path of rumbling sound based on In-Situ BF-TPA in a passenger car. In addition to identification, the passive control method for rumbling sound is presented.