Abstract
Ply break is often encountered in laminated fiber reinforced composites under impact loading and the interface of the broken ply and the adjacent intact ply acts as a preferential site for delamination initiation and propagation. Thus improving the resistance to delamination at the interface is important in design of such laminated composites. An attempt has been made to understand the influence of adding carbon nano tubes (CNTs) with epoxy in improving resistance to delamination at the interface of broken and intact plies in three phase carbon/CNT-epoxy laminated composites. Carbon/CNT-epoxy laminates with the central ply broken has been considered and three dimensional finite element analysis (FEA) has been carried out. Virtual crack closure integral (VCCI) and quadratic stress criterion (QSC) have been used to evaluate critical strain energy release rate (Gc) as a measure of resistance against delamination. Considering different percentage of CNTs in epoxy, results show that addition of CNTs with the epoxy matrix up to a certain percentage leads to significant enhancement of Gc indicating the improvement in resistance to interfacial delamination.