Coupling theoretical data and translational FRFs to perform distributed structural modification

Predicting the effect of distributed structural modifications, such as rib or plate stiffeners, on structures for which a theoretical model is not available, is not practically considered in the technical literature: this is due to the objective difficulty of coupling continuous modifications with an original structure known through its frequency response function. While this is not the case when lumped modifications are accounted for, the possibility of describing distributed modifications requires non-trivial operations involving the use of different models for the structure and the modification, an appropriate use of a condensation procedure and a careful consideration of non-local effects introduced by the above condensation. The basic requirements for a consistent modelling are here considered and some results are presented.