Nondestructive evaluation of linterfacial and damage sensitivity for single fiber/epoxy composites with PVDF and PZT sensors using micromechanical test and acoustic emission

Damage sensing and interfacial evaluation of single-glass or basalt fibers/epoxy composites were performed by micromechanical technique and acoustic emission (A-E). Piezoelectric lead-zirconate-titanate (PZT), polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer were used as AE sensor, respectively. For glass fiber/epoxy composite, the fiber fracture, matrix crack and possible interfacial debonding signals were detected by PZT sensor, whereas the fiber fracture signals were detected mainly by PVDF sensor because the sensitivity of PZT sensor was higher than that of PVDF sensor. The sensitivity of P(VDF-TrFE) copolymer sensor was rather higher compared to conventional PVDF sensor case. In case of embedded polymer sensors, responsing sensitivity was higher than that of the attached case. It can be due to fully constraint inside specimen to transfer elastic wave coming from micro-defomation.