Vibro-acoustic modelling in the mid-frequency range of a 2D system for structure-borne analysis

Being able to predict the vibratory behaviour of a complex structure in the mid-frequency field, has become nowadays a strong matter of concern in the automotive industry. The mid-frequency field is defined as the domain where the stiff (respectively the soft) subsystem will have a low frequency (respectively high frequency) response. A hybrid formulation for investigating the vibro-acoustic response of a structure in the mid- frequency field will be presented in this paper. A stochastic formulation called the Smooth Integral Formulation, based on the classical boundary integral equations, is used to model the high-frequency subpart of the structure. The random formulation is coupled with a finite element formulation which models the low-frequency subpart. The hybrid method enables to predict, in the mid-frequency field, the well separated peaks non sensitive to any randomness and generated by the “low frequency” subsystems, as well as a smooth trend of the strongly oscillating part of the response, due to the high frequency behaving substructure. Finally, the formulation will be validated and its effectiveness illustrated by running simulations for assembled 2D structures.