Self-sensing hybrid composite laminate by piezoelectric nanofibers interleaving

One of the most critical aspects of composite materials is their vulnerability to impact loadings. In recent years, Structural Health Monitoring (SHM) systems have been developed to continuously watch over on the event of an impact and so monitor the health status of the structure. However, this technique needs the integration of sensors in the composite laminate, like Fiber Bragg Grating or piezoelectric ceramic transducers, which often can dramatically reduce the inherent strength of the hosting material. The aim of this work is the integration of the composite laminate with a nanostructured piezoelectric sensor, based on PVDF-TrFE nanofibers and aluminum sheets as electrodes. Structurally, the resulting composite is a hybrid laminate known as Glass Laminate Aluminum Reinforced Epoxy (GLARE), consisting of aluminum sheets alternatively bonded to glass-epoxy prepreg layers, functionalized with PVDF-TrFE interleaved nanofibrous mats. Hence, this nanostructured hybrid laminate becomes itself a piezoelectric sensor, capable to detect impacts on its whole surface. Non-destructive impact tests were performed using an instrumented drop-weight tower to investigate the real-time electrical response of the self-sensing laminate. A lumped electric model was applied to study and optimize the circuit electrical parameters. Then, the self-sensing laminate performance were evaluated in terms of linearity and spatial uniformity.