Application of smoothing techniques to damage detection using Proper Orthogonal Decomposition

Damage identification is a key factor in many engineering fields, especially in those where the safety of people is involved, as aeronautics. Many damage detection techniques require a baseline of the intact structure to evaluate the presence of the defect. The Gapped Smoothing Method (GSM) has already been investigated as a possible way to overcome this limitation. However it has been applied to simple structures as cantilever beams and plates, which are not commonly used in the aeronautical field. In the present paper a damage detection technique based on the Proper Orthogonal Decomposition (POD) is presented. The application of the GSM to the curvature of the modes shows the capability of detecting the damage in simple structures, while in the case of a more complex structure as a stiffened panel more manipulation of the damage indices were required in order to overcome the sharp variation on the curvature caused by the stiffener. Different positions and types of damage were investigated.