Tire Noise and In-Wheel Motor Noise in FE Simulations for Pass-By Noise Predictions

Pass-by noise measurement is mandatory for automotive manufacturers for conformity of production. With evolving of pass-by noise requirements (under 68 dB in 2024), all the stakeholders should be able to comply with this criterion. OEMs, suppliers of passive acoustic treatments, road manufacturers and tire manufacturers are concerned and should deploy efforts to provide solutions for control of exterior noise. In this regard, simulations are preferable over measurement campaigns as they can provide fast feedback on passive exterior treatments for exterior noise control. In the particular case of Lightyear vehicles, the main contributors to pass-by noise are tires and in-wheel motors. Considering that, a contribution of each of these two sources of noise to pass-by noise will be described. Tire noise sources and motor noise sources will be replaced by simple monopole sources. The best monopole source location for both tires and motors is discussed. Actran vibro-acoustic Finite Element software is used to predict the noise at pass-by microphones. The calculation process takes advantage of advanced techniques to optimize the process. The acoustic transfer functions (TFs) from monopole sources to microphones are calculated first. The TFs are computed in different conditions considering acoustic treatments in different areas. Finally, these transfer functions are recombined with source strengths from tire and motor monopole sources. The pass-by noise simulation results are compared to the pass-by noise test results to conclude on the simulation accurateness.