Experimental investigation on tensile property of stitching joint 3D braided composites

The stitching joint 3D braided composites with various stitching direction , lap length and stitching densi2
ty were experimentally studied to reveal the effect of stitching parameters on the tensile property. The tensile prop2erty of the stitching joint 3D braided composites was compared with that of 3D integral braided composites. The re2 sult s indicate that the tensile st rength and modulus of the stitching joint 3D braided composites are lower than those of 3D integral braided composites. The tensile st rength reduces about 25 %～50 % , and the initial modulus decreases 35 %～55 %. The tensile st rength and modulus are influenced by the lap length greatly. The tensile property of the composites shows the character , which the tensile property increases earlier , and then falls with the lap length increasing. When the ratio of lap length to width of the sample is about 2. 5 , the tensile property of the stitching joint 3D braided composites is bet ter , only a decrease of 25 %. The tensile property of the middle stitching density is bet ter comparatively. However the tensile property has no notable change with the stitching direction.