Investigation of interleaf sequence effects on impact delamination of nano-modified woven composite laminates using cohesive zone model

Applying nanofibrous mats between layers is one of the best methods for toughening of composite laminates. So far, many studies have been conducted for investigating the effect of various thermoplastic nanofibers on mode-I and mode-II fracture toughness, but limited studies have been done on the response and damage of interleaved laminates under low-velocity impact. Therefore, first, a laminate which its all ten layers interleaved by nanofibers is considered, then the influence of using five nanofibrous mats (half of the required mats to interleaved all layers) on delaminated area in different interleaf sequences is investigated. For this aim, the cohesive parameters of reference and Nylon 6,6-interleaved laminates (for mode-I and mode-II delamination) are obtained by numerical and experimental analyses and then the impact loading is modeled by ABAQUS/Explicit. The results show that utilizing Nylon 6,6 can decrease the delaminated area 60% if all layers of laminate interleaved by nanofibers. On the other hand, it is shown when there are five mats as the modifier, the best interleaf sequence belongs to the situation in which nanofibrous mats applied in the mid-layers of laminate.