Identification of structural damage using a sensitivity approach applied to output-only data

The evaluation of the health of a structure during its operative life represents one of the main issue researchers are interested to in order to ensure reliability and reduce the operational costs. This is particularly true when dealing with helicopters, aircraft and space structures where the severe vibration environment and the demand of lighter and lighter structures push to extremes fatigue related damages, material aging and the overall capability of the structure to withstand the prescribed dynamic loadings. The addition of the emerging Output-Only-based techniques to sensitivity-based approaches, devoted to system dynamic identification, could significantly enhance the reliability of aerospace structures. The characteristics of this novel approach were experimentally investigated on an aluminum plate in order to validate the proposed technique. The testing showed the proposed methodology can identify damage to the plate by recognizable changes in the frequency response functions synthesized, in turn, from the measurement of the strain responses only.