Energy absorption mechanism of circular-square irregular section composite tubes

The energy absorption properties of composite tubes with circle cross-section are found superior to tubes with square cross-section, while the square tubes with plane surfaces are easier to combine with other parts in the assembly process, which means square tubes have advantages in practical uses. The advantages of both circle and square tubes were combined, carbon fiber and epoxy resin were used as reinforcement and matrix, respectively. Three types of circular-square composite tubes code T_15-15, T_15-60 and T_60-60 with different braiding angles including 15° and 60°, were manufactured with braiding technology and molded by Vacuum Assisted Resin Transfer Molding technology. After researching the properties of energy absorption through quasi-static compression test, it was found that through the reasonable design of braiding angle, circumferential fiber can prevent the spreading out of axial centre cracks, which could improve the energy absorption properties of fiber reinforced composite tubes for the fracture of extra fiber in the composits. The circular-square irregular fiber reinforced composite tubes with high energy absorption and easy-assemble properties were manufactured ultimately.