Vibro-Acoustic Study of a Full Vehicle Excited by an Electric Motor: Structure-Borne & Air-Borne Noise Comparison 2023-01-1112

As the automotive industry moves towards electrification, new challenges appear for evaluating the Noise, Vibration and Harshness (NVH) for full vehicles. In electric vehicles, the Internal Combustion (IC) engine, is replaced by electric motors, which have a very different NVH behavior, higher in the frequency spectrum. Two main noise contributions can be identified. First, structure-borne noise is caused by the vibrations of the motor, transmitted to the vehicle chassis by its mountings, radiating then in the cabin. Then, air-borne noise, caused by the acoustic radiation of the motor, propagating towards the panels of the vehicle, making them vibrate and produce noise inside the cabin. Being able to predict accurately these contributions on the frequency range of interest of electric motors is valuable to assess the acoustic performance of the vehicle, and study new designs to increase the passenger's comfort. In this paper, the Actran Virtual SEA approach is used to extend the frequency range of an existing full-vehicle Finite Element (FE) model. It offers the advantage to evaluate on the same model both the structure-borne & air-borne noise inside the cabin, and assess their relative impact. This is an innovative approach compared to past methods used for evaluating the NVH performance of ICE vehicles where FE models were used for low-frequency structure borne noise and SEA models for high-frequency air-borne noise. This separation is not anymore possible and reliable high frequency methods for structure borne noise are now mandatory.