Transverse impact performance and finite element analysis of three dimensional braided composite tubes with different braiding layers

The transverse impact performance of three dimensional (3-D) braided composite tubes has been studied both experimentally and numerically. Three types of braided composite tubes were manufactured by changing the number of braiding layers. The transverse impact test was performed on a modified split Hopkinson pressure bar (SHPB) apparatus under three impact gas pressures. From the tests, impact load, displacement and energy absorbed all increase with the increase of gas pressure. The increase of braiding layers leads to the increase of the impact load and energy absorption, but leads to the decrease of impact displacement. The specific load normalized by the linear density of the tubes also increases with the increment of braiding layers. The results indicated that more braiding layers contributed to higher stiffness. The impact damage modes were matrix crack, fiber breakage and shear bands at the area of impact. From the finite element method (FEM), the stress distribution on the impacted tube was highlighted plus the damage progression during the transverse impact cycles.