Improving the energy absorption capacity of square CFRP tubes with cutout by introducing chamfer

Abstract Carbon fiber reinforced polymer (CFRP) tubes have been widely used as energy absorption devices. Because it is inclined to deform in progressive crushing mode (PCM) with low initial peak force Fp and high specific energy absorption SEA (the energy absorption per unit mass). In many cases, cutouts are introduced into these tubes to meet engineering requirements. However, the cutouts can cause a collapse in the middle height (i.e., mid-height collapse mode), and thus the SEA of the CFRP tubes is even reduced by 56%. Therefore, in this research, a chamfer is introduced into the CFRP tubes with cutout to trigger the PCM, thereby increasing the energy absorption capacity. A series of validation experiments show that the chamfer can trigger the PCM with about 64% decrease of Fp and 52% increase of SEA. The parameter study is conducted to investigate the effect of size and position of the cutout on the energy absorption of CFRP tubes with a 45-degree chamfer. The result indicates that the chamfer can eliminate the negative effects of cutouts and improve the energy absorption capacity in most cases. Furthermore, the contrastive analysis between CFRP and metal tubes reveals the difference in energy absorption characteristics of these two types of tubes and further explains the advantages of energy absorption of the CFRP tubes with a 45-degree chamfer and a cutout.