Vibro-Acoustic Simulation of Mechanical Components Excited by Distributed Random Loads

The design of automotive mechanical components requires the consideration of various excitations related to physical tests (involved in the validation process) and/or operational conditions. In such a context, random distributed excitations (like diffuse field and turbulent boundary layer) play a particular role. Modeling and simulation of the vibro-acoustic response of systems subjected to such random excitations is the framework of the present contribution. Based on elasto-acoustic assumptions, on one hand, and the assimilation of the excitation to a weakly stationary random process characterized by a reference power spectrum and a particular spatial correlation function, on the other hand, the authors identify various strategies for evaluating the random response. The analysis is performed in a numerical context. The selected discrete models are based on a finite element formulation and exploit a displacement-pressure formulation. The study is done in the frequency domain (time-harmonic behavior). A particular strategy based on a sampling procedure of multi-correlated excitations is proposed. This method requires a Cholesky decomposition of the cross-PSD matrix of the excitation and the selection of random phase coefficients. The generation of multiple realizations (samples) and their parallel treatment are illustrated with practical applications. Computational performances are presented for models described in terms of physical or modal variables.