Prediction of road noise reduction using transfer path analysis with virtual spring

Conventional transfer path analysis (TPA) can derive a response at the receiver and the contribution for each transfer path of the initial base system, however, when the dynamic stiffness of the system is modified, conventional TPA cannot predict the response. In this study, a method combining conventional TPA and a virtual spring is proposed, which predicts the altered frequency response functions (FRFs), operational force, and response at the receiver when the dynamic stiffness of the system is artificially modified. The proposed method was validated through numerical simulation. Simulations were conducted by increasing the stiffness of the active and passive parts of a model resembling an actual vehicle in various cases. The proposed method successfully predicted FRFs, operational forces, and interior noise for all stiffness-modified cases. Following this, the method was experimentally validated through a dynamometer test focusing on actual road noise phenomena. The reduced interior noise was predicted by applying a virtual spring to the vehicle body. Subsequently, the predicted results were compared with measured values obtained by attaching an additional substructure to enhance the dynamic stiffness of the passive part. Notably, the proposed method accurately and virtually predicted the reduced interior noise. This method is expected to overcome the limitations of conventional TPA and augment its utility by expanding its scope of analysis.