Equivalent ‘rain on the roof’ loads for random spatially correlated excitations in the mid–high frequency range

The present paper deals with equivalent “rain on the roof” (ROF) excitations, which allow the modeling of spatially correlated broadband sources by statistically independent point forces. ROF excitation largely simplifies the expressions of the joint acceptance functions and can be easily modeled using element method (FEM). Two approaches are presented here and an equivalent model of excitation is developed and validated on acoustic and aerodynamic excitations, such as diffuse field or turbulent boundary layer (TBL) excitations. The first idea, considers the equivalence over the extended physical domain. It allows equivalent ROF excitation only for frequencies over the acoustic coincidence effect. The second method is based on the wavenumber space equivalence. Validation of this approach has been carried out for different acoustic and aerodynamic excitations, and for different structural boundary conditions. Numerical experiments show that this approach gives acceptable results for a wide frequency range specifically for TBL excitations.