  The broad application of polymer composites in engineering demands the deep
understanding of the main damage mechanisms under realistic loading conditions
and the development of proper physics-based models. Towards this goal, this
study presents a comprehensive characterization of the main damage mechanisms
in a selection of notched composite structures under multiaxial fatigue
loading. Thanks to a synergistic combination of X-ray micro-computed tomography
($\mu$-CT) and Digital Image Correlation (DIC), the main failure modes are
identified while the crack volume associated to each mechanism is
characterized. This study provides unprecedented quantitative data for the
development and validation of computational models to capture the fatigue
behavior of polymer composite structures.
