Abstract: 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 two-dimensional 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.

Key words: composites, unidirectional braiding, tensile properties, braiding angle, braided layers, damage