Thin-ply carbon fiber laminates have exhibited superior mechanical properties and damage resistance when compared to standard thickness plies, and enable greater flexibility in laminate design. However, the increased ply count in thin-ply laminates also increases the number of plyply interfaces, thereby increasing the number of relatively weak and delamination-prone interlaminar regions. In this study, we report the first experimental realization of aligned carbon nanotube interlaminar reinforcement of thin-ply unidirectional prepreg-based carbon fiber laminates, in a hierarchical architecture termed 'nanostitching'. We synthesize a baseline effective standard thickness laminate using multiple thin plies of the same orientation to create a ply block, and we find an ~15% improvement in the interlaminar shear strength via short beam shear strength testing for thin-ply nanostitched samples when compared to the baseline. This demonstrates a synergetic strength effect of nanostitching (~5% increase) and thin-ply lamination (~10% increase). Synchrotron-based computed tomography of post mortem SBS

The development of numerical tools to complement the experimental determination of structural design parameters is of key importance to hasten the certification process of new materials and structures. In this work, a methodology to simulate elastic and inelastic deformation of composite laminates at the subcomponent level based on finite element analysis is proposed. A modified version of a continuum damage model proposed in the literature combined with a frictional cohesive zone model is used to capture the intralaminar and interlaminar damage and failure of composite laminates in general loading conditions. The methodology is validated for three aerospace-grade carbon fibre reinforced (epoxy) polymer composite material systems and coupon configurations with increasing level of complexity, including unnotched tension/compression, open-hole tension/compression and filled hole compression. The predictions obtained are in good agreement with the experimental results for all the test cases, oftentimes within standard error of the tests, with maximum relative error of 13%.