Curing Monitoring of Composite Patch Using Electromechanical Impedance

Abstract

The repair technology of surface-bonded composite patches has garnered significant attention in the engineering field. The quality of the repair is directly impacted by the curing degree of the patch. Thus, monitoring the curing process of the patches is necessary. This paper proposes a real-time monitoring method for the curing of composite patches based on electromechanical impedance (EMI) technology. The proposed method can accurately track the curing process of composite patches. A piezoelectric sensor was embedded in T300 woven carbon fiber prepreg, and EMI signals were collected at 2-minute intervals during the curing process. Dielectric analysis (DEA) was performed to verify the effectiveness and feasibility of the method. The resonant resistance and correlation coefficient (CC) index were utilized to characterize the curing process of the patches. The experimental results demonstrate that the resonant resistance remains stable when the resin is converted to approximately 85%. The development trend of the CC aligns with the curing behavior of the resin, and the rate of change of the CC can reflect the speed of resin conversion. Furthermore, the proposed method can accurately monitor the curing process of both the carbon fiber prepreg patches and those bonded to an aluminum plate, demonstrating the universality of this method.