Microstructure-Sensitive Analysis of Fatigue Delamination in Notched Woven Composites via High-Resolution X-Ray Computed Tomography and Statistical Visualisation Mapping

This study presents a novel methodology integrating high-resolution X-ray computed tomography, digital volume correlation and statistical visualisation mapping, to perform microscale observations and correlate delamination fracture mechanisms in heterogeneous materials. To demonstrate the utility of this integrated approach, it is applied to study the damage behaviour of aerospace carbon/epoxy composite laminates with an open hole, subjected to quasi-static tension and fatigue at a load ratio of 1:10. The study also explores the applicability of a Paris law type relationship to determine effective macroscopic fatigue delamination resistance in the load-bearing plies. The X-ray imaging for both load cases revealed extensive formation of delaminated fracture surfaces surrounding both glass fibre interlacing weaves and entrained voids within them, acting as preferential sites for localised strain hot spots. It is demonstrated that local energy dissipation is governed by the recurring weave pattern and topological order, which can help explain the typical damage state in quasi-static behaviour, establishing a direct link between microstructural features and macrostructural material response.