非周期性三维五向编织复合材料拉伸失效机理

Tensile Failure Mechanism of Three-Dimension Five-Directional Braided Non-Periodic Composite Materials

以三维五向结构为研究对象,设计减纱工艺形成非周期性特征,进而制备碳纤维/环氧树脂三维五向编织非周期性结构复合材料。采用万能试验机与高速摄像机相结合的测试方式,获取非周期性结构拉伸力学行为及试验过程;在此基础上,通过高分辨率Micro-CT及SEM对非周期性结构试样破坏形貌进行观测,研究渐进损伤演化及最终失效机理,并与周期性结构的结果进行对比。研究表明:非周期性三维编织复合材料拉伸强度比相同结构参数周期性材料的测试值低16.84%,损伤源于减纱处,形成了应力集中,最终破坏模式以纤维束抽拔断裂为主。该研究结果可为异型编织复合材料结构设计及强度分析提供依据。

This paper was motivated by designing three-dimensional five-directional structure with the non-periodic characteristics by the process of the yarn reduction. Then carbon/epoxy three-dimensional five-directional braided composites were prepared. The universal material testing machine and the high speed camera were employed to the tensile mechanical behaviors and damage process. Furthermore,the progressive damage and final failure images were observed by using Micro-CT and scanning electron microscope( SEM). The failure mechanism of non-periodic braided composites were analyzed and compared with that of the periodic samples. The results show that the tensile strength of non-periodic 3D braided composites is 16.84% lower than that of periodic materials with the same structural parameters. The damage of non-periodic three-dimensional braided composite material is derived from the yarn reduction,and the stress concentration is formed,and the ultimate failure mode is based on the fiber bundle pulling fracture. The results of this study can provide a basis for structural design and strength analysis of special-shaped braided composites.