A study on fatigue behavior of nanointerleaved woven CFRP

Interleaving nanofibrous mats between layers of composite laminates has been proved to be an effective method for improving composites delamination resistance. The present work aims to investigate the effect of interleaving a nanofibrous mat on fatigue delamination properties of mode I loaded carbon-epoxy composite woven laminates. Double Cantilever Beam (DCB) virgin and nanomodified specimens were fabricated, these latter by interleaving a 40 micron thick mat of Polyamide nanofibers in the mid interface, where the crack was initiated. Static and fatigue tests were performed in order to determine the delamination growth onset and the crack propagation rate vs maximum energy release rate respectively. Static tests showed an increase of delamination toughness for nanomodified specimens of 130%. Crack grow ratio charts for virgin and nanomodified specimens showed that for a given propagation speed nanomodified specimens can sustain a much higher load than the virgin ones; furthermore, nanomodified specimens presented a several times slower crack propagation speed compared to the virgin ones, for a given stress.