EXPERIMENTAL CHARACTERIZATION OF MODE-II INTERLAMINAR FAILURE IN GEOMETRICALLY SCALED STITCHED RESIN-INFUSED COMPOSITES

This work is focused on investigating the impact of out-of-plane stitches on mode-II interlaminar fracture progression and crack arrestment in stitched resin-infused composites. For the experimental work, end-notched flexure quasi-isotropic specimens were manufactured using ±45 non-crimp carbon-fiber fabrics through a resin-infusion process. Both stitched and unstitched specimen sets were designed for comparison. For a size effect study, the specimens were geometrically scaled with three scaling levels. For global fracture analysis, the fracture energy of the specimen material was analyzed using a compliance calibration method and a size effect theory. For local analysis, separation development was characterized along predicted fracture process zones by analyzing in-plane displacement through the thickness from digital image correlation data. The impact of out-of-plane stitches on separation propagation was analyzed and discussed by comparing the stitched and unstitched cases. This work will contribute to understanding damage propagation and crack arrestment mechanisms in stitched resin-infused composites for high-fidelity damage model development.