Study of electromechanical impedance changes caused by modifications of CFRP adhesive bonds

Numerous techniques of nondestructive testing and structural health monitoring ofCFRP structural parts are studied. In this research, we focus on electromechanicalimpedance (EMI) technique. This technique is based on a piezoelectric sensor thatis surface mounted on or embedded in the inspected structure. Because of directand converse piezoelectric effects, the electrical response of the sensor is relatedto mechanical characteristic of the structure. In the reported research, adhesivelybonded CFRP samples were investigated. The EMI characteristics of samples withmodified bonds were compared with properly bonded referential samples. The followingmodifications were considered: prebond thermal treatment, prebond contaminationwith de‐icing fluid, and precuring of the adhesive. The EMI spectra wereinvestigated searching for anomalies and changes caused by modification of theadhesive bonds. Numerical indexes were used for the comparison of EMI characteristics.The sensitivity of the EMI method to modified bonds was observed.