An experimental study of frequency response function (FRF) based damage assessment tools

Many implementations of structural health monitoring would be enhanced by having a simple and rapid set of tools to make initial assessments of damage existence and location. Follow-on testing, analysis, and operational planning can then proceed much more efficiently. In order to meet these needs in a pre-modal extraction timeframe, a Frequency Response Function (FRF) based set of tools have been assembled and applied to the Space Shuttle VSA data set. In order to monitor the existence of damage, uncertainty bounds on FRF's are generated. Excursions from these bounds by follow-on data is indicative of a changing structure. In order to monitor the location of damage, the Substructure System IDentification (SSID) technique is used to produce the first Ritz vector for the system. The Structural Translation and Rotation Error CHecking (STRECH) approach is used to interrogate these vectors for damage location. This process is seen as the first in a family of tools to provide FRF based damage assessment.