Damage mechanism analysis of CFRP composite tube subjected to transverse impact and compression-after-impact behaviors

Carbon fiber reinforced polymer (CFRP) has drawn growing attention for its outstanding lightweight and energy absorption capacity. This work researched the effect of different wall thicknesses and diameters on both low-velocity impact (LVI) and compression-after-impact (CAI) behaviors of carbon fiber-reinforced polymer (CFRP) tubes. In this study, quasi-static impact tests were carried out to investigate the mechanical properties of CFRP tubes subject to transverse loading conditions. Based on response history and failure morphology, the results show that increasing the wall thickness can disperse the incident energy from the impact center to the outer region and improve the impact resistance of GFRP. It is worth noting that decreasing the diameter could improve the stiffness of the specimen and enhance their ability in CAI events compared with increasing the diameter of tubes, their failure evolution was presented from the perspective of digital image correlation (DIC). For instance, at an energy impact of 20J, compared with a round tube having a wall thickness of 1 mm and an inner diameter of 20 mm, the maximum displacement of a round tube with a wall thickness of 1 mm and an inner diameter of 40 mm rises from 0.43 to 0.60 mm, an increase of 39.5%.