Increasing the damage resistance of composites by interleaving them with electrospun nanofibrous veils

Delamination between reinforcing plies is one of the most important failure mechanisms encountered in composite laminates during use. Interleaving composites with electrospun nanofibrous veils is proving to be a viable technique in order to increase the delamination resistance. The veils can easily be placed in the resin rich interlayers prior to production and do not require a dispersion in the matrix resin such as traditional particle toughening techniques. Furthermore, they are easily produced by electrospinning. Although there are many expected obvious benefits, the research on composites toughened with electrospun nanofibres is still very limited. We will give thorough insight into the toughening micromechanisms that are present in laminates interleaved with nanofibrous veils. The bridging of microcracks by nanofibres is shown to be the main mechanism resulting in an increased interlaminar fracture toughness. Upon crack extension, nanofibres will bridge the newly formed crack surfaces and take up energy by straining, yielding and fracture. Several parameters are identified which influence this nanofibre bridging, and thus the observed interlaminar fracture toughness. This allows us to accurately determine the crucial parameters and toughening mechanisms which is necessary for the design of advanced damage resistance composite materials.