The Study Of The Influence Of Braided Structure On The Mechanical Behavior Of Composite Tube

Composite components have been found increasing application in various industry sectors,such as aerospace,automobile and ocean engineering,due to its high specific strength.Among of them,different methods including weaving,winding and braiding were used to manufacture the fiber reinforcement.In fact,circular braiding is specially to manufacture the seamless fiber reinforcement because of its near-net forming ability.Meanwhile,due to high automation ability of circular braiding technology,the braided composite parts make them very attractive to replace their counterpart in metal materials.Thus,the understanding of the mechanical performance and the failure mechanisms of composite braided component is important for the optimization design of braided structure.In the paper,the braided composite tubes' mechanical property is studied by the experimental and simulation means.First of all,by controlling the take up speed,the fiber reinforcement samples with different braiding angles is obtained.During the braiding process,adding mandrel is appended in the front of original mandrel in order to avoid the convergence zone of braiding angle.Next,the braid composite tube is produced using the VARTM method.And the tube is cut into suitable samples for the following experiments.Next,the tube model is built at yarn scale.According to the braided trajectory and the section of yarn observed by the CT,the braided fabric is obtained using the 3D modeling software.Due to the yarns own the property of transverse isotropy,the material local coordination is set along the direction of braided trajectory.Then,we conduct the quasi-static compression experiments for corresponding tubes.And the crush process is recorded by a camera to analyze the deformation behavior of braided fabric.The results of experiment are listed and analyzed.Two fracture modes which depend on the fabric structure are also observed.By employing boundary conditions on the model built above,a numerical analysis result is to further verify the role of braided fabric in the process.Combining the experimental phenomena and the results of simulation,the stress of fiber is analyzed in the front and rear of composite tube's fracture.Additional,the relationship between fracture mode and the braiding angle is discussed.So are the fracture mode and the SEA.Finally,quasi-static three point bending experiments are conducted for single-layer and double-layer tubes.In the final fracture mode,the delamination,cracking and peeling of resin are found.By comparing the stress distribution of resin and the results of experiment,the influence of braiding angles on strengthen of tube and its failure modes are also discussed.What's more,the enhancement mechanism of fiber is also analyzed in the front and rear of composite tube's fracture.