Assessing the retrieval procedure of complex-valued forces from airborne pressure fields by means of DIC-based full-field receptances in simplified pseudo-inverse vibro-acoustics

Abstract

Lightweight structural components in many engineering fields can be severely excited by airborne pressure fields, becoming a concern for their structural dynamics and reliability. Nowadays, the quality reached by optical measurements, in contactlessly estimating - as maps of displacements over force - complex-valued full-field receptances, allows an accurate description of the structural dynamics in a broad frequency domain, without any numerical structural model. This is even more relevant for lightweight components, otherwise affected by potential distortions, coming from the inertia of more traditional transducers. High-speed DIC structural testing is here combined with acoustic propagation in direct and pseudo-invertable vibro-acoustic FRFs, obtained by the simple Rayleigh integral approximation, here re-formulated to take advantage of the experiment-based full-field receptances, when a force excites a vibrating surface, which radiates sound pressure into air and vice-versa. Starting from airborne pressure fields, known in their spectra, the pseudo-inverse vibro-acoustics aims at identifying the force, with a broad frequency band, which can be transmitted to the excitation locations, previously used in defining the vibro-acoustic FRFs in the direct problem. Extended details and considerations on this full-field receptance-based vibro-acoustic approximation are thoroughly provided, with special attention to its complex-valued nature, to numerical precision and to broad dynamics' excitation signature, thanks to the accurate DIC-based testing of a real thin plate.