Abstract X-ray micro-computed tomography (μCT) is used to quantify morphology in AS4/8552 (autoclave) and IM7/M56 (Out-of-Autoclave, OoA) aerospace-grade advanced unidirectional-ply carbon fiber prepreg composites, revealing several previously unreported features. The micron-scale (1 μm voxel size) three-dimensional datasets combined with automated, objective algorithms, revealed the following previously unreported features of AS4/8552 and IM7/M56 laminates, respectively: all ply interfaces analyzed have misplaced microfibers at densities of 1–2 per mm2 of interface area that can contribute to the mean thickness of the interlaminar regions of 8.6 μm and 14.4 μm; all ply interfaces have elongated (aspect ratio > 10 and presumed to extend indefinitely) periodic resin pockets along the microfiber direction of the plies bounding the interlaminar region that we term tow-aligned resin pockets (TARPs), with typical thicknesses that are 2–3X greater than the average interlaminar thickness; overall void fractions are low at ~0.002 vol% and ~0.001 vol%, comprised primarily of newly-quantified "sub-microvoids" with an average volume of 26–31 μm3 that are equally pervasive in both materials, numbering ~300 per mm3. The new interlaminar region and void tools were also utilized to analyze laminates with aligned carbon nanotubes (A-CNTs), termed "nanostitches", incorporated between plies to reinforce the interlaminar regions. The addition of A-CNTs increased the interlaminar thickness by 2.2 μm and 8.0 μm for the AS4/8552 and IM7/M56 systems, respectively, but did not affect the quantity or distribution of voids or TARPs. These newly-identified features are relevant to the mechanical performance of such composites, as they may have positive or negative effects on damage initiation and progression.

中文翻译：

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通过使用微型计算机断层扫描的自动化算法揭示先进航空级复合材料的新层间特征和空隙分布

摘要 X 射线显微计算机断层扫描 (μCT) 用于量化 AS4/8552（高压釜）和 IM7/M56（高压釜外，OoA）航空级先进单向层碳纤维预浸料复合材料的形态，揭示了几种以前未报告的功能。微米级（1 μm 体素大小）三维数据集与自动化的客观算法相结合，分别揭示了 AS4/8552 和 IM7/M56 层压板的以下先前未报告的特征：分析的所有层界面都错放了密度为 1 的微纤维–2/mm2 的界面面积，可以使层间区域的平均厚度为 8.6 μm 和 14.4 μm；所有层界面都被拉长（纵横比 > 10 并假定无限延伸）周期性树脂袋沿层间区域的层间微纤维方向界定，我们称之为丝束对齐树脂袋（TARP），其典型厚度比平均层间厚度大 2-3 倍；整体空隙率低至 ~0.002 vol% 和 ~0.001 vol%，主要由新量化的“亚微空隙”组成，平均体积为 26–31 μm3，在两种材料中同样普遍存在，每平方毫米约 300 个。新的层间区域和空隙工具还用于分析具有对齐碳纳米管 (A-CNT) 的层压板，称为“纳米缝线”，并入层间以加强层间区域。A-CNT 的添加使 AS4/8552 和 IM7/M56 系统的层间厚度增加了 2.2 μm 和 8.0 μm，分别，但不影响空隙或 TARP 的数量或分布。这些新发现的特征与此类复合材料的机械性能有关，因为它们可能对损伤的发生和发展产生积极或消极的影响。