About airborne fatigue life predictions by means of full-field receptances. Part A: retrieving structural forces from pressure fields

By means of a simplified inverse vibro-acoustic relation – based on the Rayleigh integral approximation of the sound propagated by a vibrating surface, modelled by the testing-based full-field receptances – in Part A the spectrum of the induced force by the airborne pressure fields can be retrieved, taking into account all the hardly modellable conditions of the set-up realisation. This part starts therefore from the modelling of the acoustic pressure field, in its spatial and broad frequency band contents. By means of the simplified receptances-aided inverse vibro-acoustics, the complete spectrum of the induced force is retrieved in the location of the impedance head of the direct characterisation testing of the surface. Details and considerations on the airborne force retrieval method, together with examples coming from a real thin plate tested, are provided in this Part A of the work.