Damage localization in structures without baseline modal parameters

A methodology to localize and estimate the severity of damage in structures for which only postdamage modal parameters are available for a few vibrational modes is presented. First, a theory of damage localization and severity estimation that utilizes only changes in mode shapes of the structures is outlined. Next, a system identification method that combines the experimental modal data and the modal parameters of a finite element model of the structure under investigation is developed to yield estimates of the baseline (i.e., predamage) modal parameters for the structure. Finally, the feasibility and practicality of the complete damage detection algorithm are demonstrated by localizing and sizing damage in a continuous beam for which only postdamage modal parameters for a single vibrational mode is available.