Abstract Thin-ply carbon fiber laminates have exhibited superior mechanical properties, including higher initiation and ultimate strength, 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 ply-ply 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 (SBS) 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 specimens suggests a different damage trajectory and mode of damage accumulation in nanostitched thin-ply laminates, notably the complete suppression of delaminations in the nanostitched region. Finite element predictions of damage progression highlight the complementary nature of positive thin-ply and nanostitching effects that are consistent with an ∼15% improvement in Modes I and II interlaminar fracture toughness due to the aligned carbon nanotubes at the thin-ply interfaces.

中文翻译：

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复合材料层压板中薄层与定向碳纳米管层间增强的协同效应

摘要 与标准厚度层相比，薄层碳纤维层压板表现出优异的机械性能，包括更高的起始强度和极限强度，并且在层压板设计中具有更大的灵活性。然而，薄层层压板中增加的层数也增加了层-层界面的数量，从而增加了相对薄弱和易于分层的层间区域的数量。在这项研究中，我们报告了在称为“纳米缝合”的分层结构中首次实验实现了薄层单向预浸料基碳纤维层压板的对齐碳纳米管层间增强。我们使用多个相同方向的薄层合成基线有效标准厚度层压板，以创建层块，并且我们发现与基线相比，通过短梁剪切（SBS）测试，薄层纳米缝合样品的层间剪切强度提高了约 15%。这证明了纳米缝合（增加约 5%）和薄层层压（增加约 10%）的协同强度效应。基于同步加速器的验尸 SBS 标本计算机断层扫描表明，纳米缝合薄层层压板存在不同的损伤轨迹和损伤累积模式，尤其是纳米缝合区域的分层完全抑制。损伤进展的有限元预测突出了正薄层和纳米缝合效应的互补性，这与由于薄层界面处排列的碳纳米管而导致的模式 I 和 II 层间断裂韧性提高约 15% 一致。