VIBRO-ACOUSTIC RESPONSE OF A STIFFENED PANEL UNDER SYNTHETIZED SPACE-TIME RANDOM EXCITATIONS
Résumé
In the framework of the VIRTECH ANR project, alternative experimental methods are developed to replace or complement the use of large and costly facilities (reverberant room, wind tunnel) for the vibro-acoustic characterization of structures under random excitations (Diffuse Acoustic Field-DAF, Turbulent Boundary Layer-TBL, respectively). In the case of TBL excitation, numerical methods are investigated to replace Computational Flow Dynamics (CFD) methods that are computationally costly, even when flat panels without obstacle nor pressure gradient are considered. In that context, this work presents a space-time (2D+t) synthesis approach to efficiently synthetize a wall pressure field that can be coupled to a deterministic vibration model of the structure. Any model of wall pressure field (autospectra, correlation length) can be used to set up the synthesis approach to represent random excitations like DAF or TBL. The pressure field radiated by the panel can even be obtained in the time domain, and be used for sound perception purposes to evaluate the variations linked to the damping of the structure, the empirical model used for the synthesis (eg. Corcos, Mellen) or the probability density functions of the wall pressure excitation (Gaussian or non Gaussian). In the present work, a deterministic finite element model of a stiffened panel is coupled to 2D+t stationary wall pressure fields to obtain its vibroacoustic response under DAF and TBL excitations in the frequency domain.
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