Experimental analyses on local diagnoses through additional poles extracted by R-FRFs

Within the area of structural dynamics, as for example damage detection and model updating, modal data are extensively used throughout diagnosing of structures. Such diagnoses are generally based on the variations of poles and modes caused by damage and structural modification. In this work, we show the existence of additional poles which can enrich the intrinsic modal database and allow as well to carry out local diagnoses on the system. The possibility to extract such poles from certain response-based frequency response functions (i.e. R-FRFs achieved regardless of knowing exciting forces) is also illustrated. The present is a mainly experimental-based investigation that, aimed at confirming certain previously illustrated theoretical findings, will let the analyst identify the location of structural modifications by measurement procedures in situ not requiring the usage of numerical models.