Real-time in-situ damage monitoring of composite laminate via embedded PVDF piezoelectric nanofibers film

Structural health monitoring (SHM) of fiber-reinforced polymer (FRP) structures is of paramount importance for their safe and reliable service. However, conventional non-destructive testing (NDT) and non-self-powered SHM techniques suffer from inherent limitations, including insufficient real-time characteristics, the need for an external power supply, and potential degradation of structural integrity. In this study, a flexible piezoelectric nanofiber film fabricated via electrospinning was embedded in FRP laminates to develop a self-sensing laminate. The incorporation of functional fillers enables in-situ damage monitoring of the FRP structures and also enhances the piezoelectric performance. Hydroxylated barium titanate (BTO-OH) and hydroxylated multi-walled carbon nanotubes (MWCNTs-OH) resulted in an increase of the voltage output of the PVDF film from ∼10 V to ∼60 V compared to the pristine polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) film. Mechanical testing showed that the embedded film did not cause a significant reduction in the measured interlaminar shear strength, flexural, and low-velocity impact performances. The in-situ damage monitoring method obtained an average localization error of 3.538-5.365 mm within an impact energy range of 5 J to 13 J. The relative error between the predicted and actual damage areas was 1.4% at 13 J. The proposed embedded flexible piezoelectric nanofiber film sensor achieves in-situ damage monitoring and self-sensing of composite laminates, offering a novel solution for SHM.