二维二轴单向编织铺层复合材料拉伸性能的研究

TENSILE PROPERTIES OF TWO-DIMENSIONAL TWO-AXIAL UNIDIRECTIONAL BRAIDED COMPOSITE

提出了一种新型的二维二轴单向编织结构,研究了编织角和纤维体积分数的变化对该种结构复合材料拉伸性能的影响,并结合编织结构的特点分析了试样在拉伸破坏过程中的裂纹扩展模式。结果表明,上述编织复合材料的拉伸强度随纤维体积分数的增加而增加,但编织角的小幅度变化对拉伸性能影响较小。受编织结构的影响,试样内部在拉伸载荷作用下形成了两种分布规律的裂缝,层内裂缝沿样品厚度方向延伸,相邻铺层内的裂缝没有构成连续的扩展;层间裂缝沿着层与层的接触面延伸,表现为层间分层效应。二维二轴单向编织铺层复合材料内部裂缝的扩展模式综合表现为由上下铺层逐层向中心铺层扩展。本文的研究结果对于该类结构材料的设计与应用具有一定的指导意义。

A new braided structure named two-dimensional two-axial unidirectional braided structure was proposed in this paper. Different specimens were prepared to study the influence of different braided angle and fiber volume fraction on its tensile properties. Further investigation was made to study how cracks stretch in this composite under tensile loading process. Experimental results reveal that tensile strength of this composite increases with the increase of fiber volume fraction,but small changes of braided angle has little influence on tensile properties of twodimensional two-axial unidirectional braided composites. With the influence of braided structure,there are two kinds of cracks,in-layer cracks which stretch along the thickness direction of specimens and interlayer cracks which extend along layers＇ contact surface. In general,cracks are showing the extending trend from upper or lower layers to the center layer.The study in this paper gives guiding significance for the design and application of this kind of structural material.