三维五向编织复合材料纵向性能的实验研究

通过对具有不同编织结构参数的三维五向编织复合材料试件的纵向拉伸和压缩实验,分析了该类材料的纵向拉、压刚度和强度随编织工艺参数的变化规律以及材料的失效形式.三维五向编织复合材料在破坏前基本保持线弹性,纵向拉、压破坏具有脆性特征,拉伸模量和压缩模量比较接近,但拉伸强度远大于压缩强度.编织角和纤维体积含量对材料性能的影响显著,纱线粗细的影响不大.提高第五向纱线的比例,可提高材料的纵向性能.此外,研究中采用短标距薄板试件,以避免试件产生整体屈曲和端部纤维束开裂破坏.

Experimental Investigation on Longitudinal Properties of 3-D 5-Directional Braided Composites

The longitudinal tensile and compression tests were conducted on the 3-D 5-directional braided composites with different braiding parameters. The effect of braiding parameters on the longitudinal tensile and compressive properties was discussed, and the failure mechanism of materials was investigated. The stress-strain curves showed that the longitudinal tensile and compressive properties of 3-D 5-directional braided composites were linear elastic, and had brittle fracture characteristics. Tensile modulus was almost equal to compressive modulus, but the tensile strength was far higher than compressive strength. Braiding angle and fiber volume fraction had significant influence on the mechanical properties of 3-D 5-directional braided composites, but the linear density of yarns had little effect. Increasing the proportion of axial yarns could improve the longitudinal properties of materials. Moreover, shot-gauge plate samples were used to avoid the buckling and end cracking.