Abstract This paper presents the influence of the off-axis angles on the low-velocity impact (LVI) and compression after impact (CAI) damage mechanism of three-dimensional (3D) woven carbon/epoxy composites. Three kind of samples with different angles, 0°, 30° and 45°, of the weft and warp yarn orientation were experimentally tested using the drop weight LVI and quasi-static CAI equipment. X-ray micro-computed tomography (Micro-CT) techniques were used to identify the impact damage volumes, damage distribution and damage modes of 3D woven composites. Results indicated that the off-axis angles have significant effects on the LVI and CAI mechanical behavior and final failure mechanisms. Furthermore, Micro-CT revealed that off-axis samples exhibit more damage volumes and out-of-plane deformation. More importantly, the ultimate CAI strength of all the samples are largely governed by the global buckling. However, the formation of buckling damage in 0° samples runs from one edge of the specimen to the other side, whereas that in 30° and 45° samples mainly occur along the weft direction.

中文翻译：

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离轴角对 3D 编织复合材料的低速冲击和冲击后压缩损伤机制的影响

摘要 本文介绍了离轴角对三维（3D）编织碳/环氧树脂复合材料的低速冲击（LVI）和冲击后压缩（CAI）损伤机制的影响。使用落锤LVI和准静态CAI设备对纬纱和经纱取向的三种不同角度0°、30°和45°的样品进行了实验测试。X 射线显微计算机断层扫描 (Micro-CT) 技术用于识别 3D 编织复合材料的冲击损伤体积、损伤分布和损伤模式。结果表明，离轴角对 LVI 和 CAI 力学行为和最终失效机制有显着影响。此外，Micro-CT 显示离轴样品表现出更多的损伤体积和平面外变形。更重要的是，所有样品的最终 CAI 强度在很大程度上取决于全局屈曲。然而，0°试样屈曲损伤的形成是从试样的一个边缘向另一侧延伸，而30°和45°试样主要沿纬向形成。