Abstract: In order to improve the joint strength between the ribs and the skin in the T-reinforced wall panel of the composite material, stitching reinforcement technique is introduced. The self-developed curved needle sewing machine is used to prepare the suture T-joint sample by vacuum assisted resin infusion technique (VARI), and the tensile test is carried out to study the interface strengthening mechanism of the T-joint and the influence of stitch density and stitch fineness on the tensile properties of T-joint. The results showed that when stitching fineness is 1000 D and the stitching density is in the range of 0-10×10, the tensile limit load of the suture-reinforced T-joint increased with the increase of the stitching density. The ultimate load of stitched reinforced T-joints with stitch density of 10×10 is 38% higher than that of unstitched joints. The ultimate tensile load of stitched T-joints tends to decrease in the range of stitching density of 10×10-8×8. When the stitching density is 10×10, and the stitch fineness is in the range of 0-1000 D,the tensile load-carrying capacity of the T-joint increases with the thickening of the suture, and the tensile limit load of the T-joint decreases when the stitch fineness increases to 1500 D. The change in stitch density and seam fineness has no significant effect on the initial failure load of the T-joint.

Key words: T-joint, VARI, stitching density, stitching thread fineness, tensile test