A novel multi-damage localization method for polymers and composites based on electromechanical impedance

The electromechanical impedance (EMI) method has shown its damage detection capability for lightweight structures due to its damage sensitivity. In this paper, a new technique based on the uniform sensor network for multiple damage localization was proposed. The EMI-based damage indices were obtained from several piezoelectric transducers and fused for multiple-damage localization for the first time in literature. In the proposed approach, the sensor sub-network selection employs the vertices of a triangle based on the calculated sensing region radius. The method employs sub-networks to allow multiple damage sites localization without prior information about the number of damage sites to be found. These sub-networks approaches were applied to detect and localize the two and three damaged sites simultaneously. The glass fiber reinforced polymer (GFRP) and 3D-printed acrylonitrile butadiene styrene (ABS) plates were used for the investigation, with surface-bonded piezoelectric transducers (PZTs). Magnets were used to simulate multiple-damage positions, and drilled holes were used as more realistic multiple-damage. In the investigated cases the EMI data displays damage-sensitive peaks in a frequency range of 1 kHz to 200 kHz. The results show successfully the detection and localization of multiple-damage sites in additively manufactured (AM) polymer and fiber-reinforced composite plates. It was observed that the damage localization error increases significantly with the new damage introduced in the structures.