The mode I interlaminar fracture behavior of the composite laminates reinforced with the Zanchor process, which is a novel through-the-thickness reinforcement technique utilizing an elaborated needling process, was studied on the basis of the experimental results of DCB tests. Experimental results demonstrated that the mode I interlaminar fracture toughness was improved effectively by the Zanchor reinforcement, where the fracture toughness, G_<IC>, increased almost linearly with the Zanchor density, Z. In addition, the fracture toughness, G_<IC>, increased drastically during the early stage of crack extension in the Zanchor reinforced composites, where the interlaminar crack propagated stably accompanied by a large amount of fiber bridgings. The above results suggested that the increase in mode I fracture toughness was the consequence of the fiber bridgings induced by the Zanchor process.
