Damage detection in structures from vibration and wave propagation data

Development of efficient tools to successfully localize and characterize hidden damage in critical structural components is an important task in the design and construction of structural health monitoring systems in aging as well as new structures. In this paper two methodologies for damage identification and localization will be presented. The first is an automatic numerical scheme using a state space system identification approach and the second is based on certain damage correlation indices associated with changes in the frequency response of the structure in presence of flaws. In each case, the structure is to be instrumented with an array of sensors to record its dynamic response including vibration and wave propagation effects. To determine the type and location of an unknown defect, the sensor data detected is used to identify a new system, which then is compared to a database of state-space models to find the nearest match. The second method deals with the definition of a set of damage correlation indices obtained from the frequency response analysis of the structure. Two types of indices have been considered. The first uses the correlation between the responses of the defect free and damaged structure at the same point, and the second uses correlation at two different points. The potential application of the general approach in developing health monitoring systems in defects-critical structures is discussed.