Controlled interlaminar crack initiation in thin notched laminated thermoplastic composites under impact loading: A first step towards unitary layer recovery

Abstract

The recycling of composite materials is nowadays a major challenge as it is systematically associated with a downcycling due to the reduction of the fiber length. However, recent works demonstrated that the delamination-based recovery of the unitary layers of laminated structures with preserved mechanical properties is possible under dedicated loading conditions. The presented work aims at investigating this innovative process and in particular the interlaminar crack initiation from a straight notch milled in the material by using an impact loading; further crack extension to recover the complete lamina being the following step of the process. A Split Hopkinson Bar setup has been used in a Direct Impact configuration and a dedicated test setup has been implemented to impose translational and rotational kinematics to the impacted side of the tested specimens in order to enable crack initiation and propagation over a few millimeters. Imposing translational kinematics to the impacted side of the specimen has been shown to induce cracks in a reproducible manner. Numerical simulation results explain the more favorable conditions provided by the translational kinematic.