Effect of stacking configuration on the mechanical property and damage behavior of braided composite tube under three-point bending

Composite tubes have an asymmetry deformation and loading distribution under transverse bending. This work investigated the effect of the stacking sequence on the critical damage to a hybrid tube with 45 degrees and 60 degrees braided layers. In-situ infrared thermal imaging was adopted to observe the initiation and development of internal damage. As the outermost reinforcing material in the stacking structure, the 60 degrees braided layer with high contact strength inhibited damage to the contact area at the top and improved the bending strength of the specimen at the initial stage of loading. As the inner reinforcing material in the stacking structure, the 45 degrees braided layer with high bending toughness maintained the high stability of the load-carrying capacity during bending and restrained the tensile failure at the bottom of the tube. However, the interlaminar interface of braided layers with different braiding angles reduced the interlaminar fracture toughness. The interlaminar delamination failure developed rapidly as the bending at the bottom of the tube increased. This delamination damage determines the peak load-carrying capacity of the laminated structure.