Ageing conditions and braided structures will affect dynamic damage and failure mechanisms of 3D braided composites. Here we report the influence of thermo-oxidative ageing on impact compression behaviors of 3D braided composite with and without axial yarns, i.e., four directional (3D4d) and five directional (3D5d) braided composites. We found a significant difference in mechanical properties between epoxy resins and composites after ageing. The impact compressive strength of epoxy resins declined rapidly and then slowly, while the composites decreased continuously, with the increase of ageing days. The interfacial debonding is main degradation mechanism for both braided composites at the later ageing stage. Thermo-oxidative ageing accelerates the inner damage evolution which propagates from surface cracks. Compared with 3D4d braided composites, the 3D5d braided structure has higher strength retaining level after ageing. In addition, the 3D5d braided samples have higher resistance to impact deformation and lower crack propagation. Finite element analysis (FEA) results revealed that 3D5d composites showed higher load carrying capacity and less damages than 3D4d composites.

老化条件和编织结构将影响 3D 编织复合材料的动态损伤和失效机制。在这里，我们报告了热氧化老化对具有和不具有轴向纱线的 3D 编织复合材料的冲击压缩行为的影响，即四向 (3D4d) 和五向 (3D5d) 编织复合材料。我们发现老化后环氧树脂和复合材料之间的机械性能存在显着差异。随着老化天数的增加，环氧树脂的冲击抗压强度先快后慢下降，而复合材料持续下降。界面剥离是两种编织复合材料在老化后期的主要降解机制。热氧化老化加速了从表面裂纹扩展的内部损伤演变。与 3D4d 编织复合材料相比，3D5d编织结构在老化后具有更高的强度保持水平。此外，3D5d 编织样品具有更高的抗冲击变形能力和更低的裂纹扩展。有限元分析（FEA）结果表明，3D5d 复合材料比 3D4d 复合材料具有更高的承载能力和更少的损伤。