Abstract The torsional performance of bi-axially braided carbon fibre reinforced polymer (CFRP) tubes as a function of braid architecture is investigated. It is found that for a given braid pattern, the 45° braided CFRP tubes have higher shear moduli and lower shear strength than the 35° braids. In general, 2/2 (regular) braided CFRP tubes exhibit both higher shear strength and higher shear modulus than 1/1 (diamond) braids. However, beyond the peak load, the shear strength of 2/2 braided CFRPs exhibits sudden and steep drops, resulting in a lower remnant shear strength than 1/1 structures after the shear strain exceeds 4.5%. Moreover, the damage evolution is monitored in-situ by synchrotron X-ray computed tomography during torsional straining. It shows that for a 2/2 structure, inter-tow debonded regions are vertically interconnected allowing rapid crack propagation and strength drops, whereas for the 1/1 braid they are distributed in a chequer board pattern causing a more gradual loss of strength. The fibre/matrix interfacial strength and tow cross-over density play key roles in the torsional failure of 1/1 and 2/2 braided CFRP tubes, as the former controls damage initiation and the latter controls damage propagation.

中文翻译：

---

跟踪编织结构对碳纤维/环氧树脂复合管在扭转应变期间的性能和损坏的影响

摘要 研究了作为编织结构函数的双轴编织碳纤维增强聚合物 (CFRP) 管的扭转性能。发现对于给定的编织模式，45°编织的CFRP管比35°编织具有更高的剪切模量和更低的剪切强度。通常，2/2（常规）编织 CFRP 管比 1/1（金刚石）编织管具有更高的剪切强度和更高的剪切模量。然而，超过峰值载荷后，2/2 编织 CFRP 的剪切强度突然急剧下降，导致剪切应变超过 4.5% 后的残余剪切强度低于 1/1 结构。此外，在扭转应变期间，通过同步加速器 X 射线计算机断层扫描原位监测损伤演变。它表明对于 2/2 结构，丝束间脱粘区域垂直互连，允许裂纹快速传播和强度下降，而对于 1/1 编织层，它们分布在棋盘格图案中，导致强度逐渐下降。纤维/基体界面强度和丝束交叉密度在 1/1 和 2/2 编织 CFRP 管的扭转失效中起关键作用，因为前者控制损伤开始，后者控制损伤传播。