Abstract This paper investigates damage progression during Open-Hole Tension (OHT) test of carbon fibre-reinforced composites with different Quasi-Isotropic (QI) layups. Digital Image Correlation (DIC) and in-situ edge microscopy are utilized simultaneously to detect damage on the specimen’s surface and in the inner plies, respectively. It is found that damage does not always initiate in the 90° plies, but also in the surface 45° plies, depending on the orientation of the adjacent ply. DIC resulting strain field on the surface does not necessarily have the same butterfly-shape concentration around the hole, in all layups. Some laminates show large free edge delaminations at 45°/90° interfaces. This study adds in-situ evidences to the existing data on damage during OHT test of QI laminates, providing quantitative and comparative information on different damage modes, and reveals new features of the damage phenomena.

中文翻译：

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碳纤维增强复合材料开孔拉伸试验中层间和层内损伤的原位成像

摘要 本文研究了具有不同准各向同性 (QI) 叠层的碳纤维增强复合材料的开孔张力 (OHT) 测试过程中的损伤进展。同时利用数字图像相关 (DIC) 和原位边缘显微镜分别检测试样表面和内层的损伤。发现损坏并不总是在 90° 层中开始，在表面 45° 层中也会发生，这取决于相邻层的方向。在所有叠层中，DIC 在表面上产生的应变场不一定在孔周围具有相同的蝴蝶形浓度。一些层压板在 45°/90° 界面处出现大的自由边缘分层。这项研究为 QI 层压板 OHT 测试期间的现有损坏数据增加了现场证据，