Abstract: Debonding damage is one of the most common damage in composite structures, which is not easily detected but poses a serious threat to structural safety, so its detection is very important to evaluate the safety of composite structures. In this paper, based on the electro-mechanical impedance technique (EMI), the root mean square (RMS) and the peak corresponding frequency (f_max) of the real part of the impedance curve are used as discriminators to distinguish the debonded and non-debonded regions in carbon fiber composites with the help of piezo-structural coupling field analysis. Next, the different degrees of debonding of carbon fiber composites were quantified and compared using the root mean square deviation (RMSD), mean absolute deviation (MAPD) and correlation coefficient deviation (CCD) of damage metrics. The results show that the discriminant indexes RMS and f_max can well distinguish the debonded and non-debonded regions in carbon fiber composites, and the damage indexes RMSD and CCD can better characterize the degree of debonding.

Key words: EMI, RMS, impedance real part curve, damage index, finite element model, composites