EXPERIMENTAL AND NUMERICAL STUDY ON THE DELAMINATION BEHAVIOUR OF INTERLEAVED COMPOSITES WITH AUTOMATED TAPE LAYING

Automation of composite materials manufacturing is an important pre-requisite to upscaling the manufacturing without diminishing quality of the end-products. In this research, interleaved composites have been manufactured by modified skip tow automated tape laying (ATL) process, where each tape can cross many tapes multiple times. This tape architecture has been shown previously to reduce delaminations through the internal/inherent crack arresting features. Here, Single Leg Bending (SLB) experiments were carried out to study the delamination behaviour of the interleaved composites under quasi-static loading. It was found that, following from delamination initiation, the crack plane propagated with a new crack regularly deviating/migrating away from the primary inter-tapes crack plane towards other inter-tapes interfaces due to the gaps, misorientations and interleaves between the tapes. The multiple delaminations fracture toughness was qualified by the compliance calibration (CC) method in which the fracture toughness was theoretically calculated by crack length back-calculated specimen compliance, and was also numerically modelled by accounting for large-scale fibre bridging. Moreover, both optical microscopy and X-ray computed tomography were performed to examine defects in the specimens before testing and damage after testing. It was observed that the generation of multiple cracks was heavily depended on the local lay-up structure. This suggests
EXTENDED ABSTRACT