Abstract
This paper systematically investigates the effects of various braidingparameters, pitch- length, axial yarn contents, number of braiding layers andfibre types, on the crushing failure modes and specific energy absorption capabilityof three-dimensional (3-D) braiding composite square tubes. Quasi-static axialcompressive crush tests were carried out in this study. The results show thatthe crushing failure modes and energy-absorption capabilities weresignificantly dependent upon the braiding parameters. There were four differentcrush failure modes observed in this work. They were splaying, folding, spiky-folding and splaying-curling. The specific energy absorption capabilityincreased with decreasing braiding pitch-length. The larger numbers of braidinglayers led to higher energy absorption capability. Based on the crush failuremechanism, the axial yarns were the main sources of energy absorption and thebraiding yarns were the controllers for crush failure modes. Tubes made withcarbon fibre axial yarns displayed higher energy absorption capability, whereasthe tubes made of Kevlar braiding yarns exhibited better post-crush integrity. The tubes with carbon axial yarns and Kevlar braiding yarns not only had higherenergy absorption capability but also exhibited better post-crush integrity.