Using Blocked Force Data for Vibro-Acoustic Prediction and Simulation

The context of the paper is the need across many industries for prediction and simulation of vibro-acoustic response of assembled structures. One of the main areas of difficulty is to know the excitation forces. The blocked force method allows vibration sources to be characterised independently using conventional measurements similar to those used in Transfer Path Analysis (TPA). A major advantage is that the blocked force data remains valid when for example the same vibration source is attached to different receiver structures. It is shown how measured blocked forces can be validated using an ‘on board validation‘ procedure. Progress in the standardisation of the blocked force method is also described. The question is then considered of how this blocked force data can be fed into vibro-acoustic models to provide realistic excitation and response prediction. It is shown that a substucturing step is needed in which the passive properties of the source and receiver structures are combined. Examples are presented to demonstrate that this substructuring step can be a source of significant error and ways of minimising the errors are discussed.