A real-time electromechanical impedance-based active monitoring for composite patch bonded repair structure

With the increase of serving time, the metallic primary structures are extremely likely to risk structural failures due to aging and external loads. Composite patch bonded repair offers an effective technique for recovering the ultimate load-bearing capability of the structure. Disbond between the composite patch and the substrate is a typical failure mode that severely reduces the structural stiffness and strength of repair region. In this paper, a combining active monitoring scheme is proposed based on electromechanical impedance (EMI) and coupling constitutive equations. Two statistical damage indices (DIs), root mean square deviation (RMSD) and mean absolute percentage deviation (MAPD), are adopted for locating the disbond and evaluating its severity based on extracted signatures. Experiments on the repair structure with a 3 x 3 sensors array are performed to monitor the disbond between repair patch and substrate. The experimental results show that both disbond locations and seventies on the bondline can be monitored efficaciously with the proposed active monitoring scheme.