Tyre noise and in-wheel motor noise in FE simulations for Pass-By Noise Predictions 2023-01-1094

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 tyres and in-wheel motors. Considering that, a contribution of each of these two sources of noise to pass-by noise will be described. Tyre sources and motor sources will be replaced by simple monopole sources. The results of this simulation will be compared to the pass-by noise measurements. The goal of the simulation is to provide the best possible passive exterior treatment, namely wheelhouse liners, under-engine shields, under-body panels and under-trunk panels. To achieve this goal, 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 or not acoustic treatments in different areas treated and admittance values. To speed-up the computation, acoustic super elements are used enabling a fast restart capability. A second step consists in recombining these transfer functions with source strengths. Finally optimal configuration(s) of the surface of acoustic treatments versus acoustic gain is assessed.