Finite element analysis of toughening mechanism for interlayer-toughened composites

Interleaving, incorporating tough adhesive interlayer between laminars, is an effective method to improve delamination resistance by enlarging interlaminar zone and lowering crack-tip stress intensity. In order to investigate the interlaminar fracture toughness both for interleaved and non-interleaved laminates and further illustrate toughening mechanisms, two dimensional finite element analysis was carried out. The results show that the J-integral, stress intensity factor and stress magnitude was significantly reduced both for mode I and mode II fracture. The influence of interlayer modulus and thickness on these fracture parameters was also determined. The high stress distribution in the region close to the interface between interlayer and laminar can be the driving force for interfacial failure.