Enhancing residual energy-absorption of perforated CFRP tube by a critical transition of failure mechanism

Abstract For enhancing residual energy-absorption (EA) of perforated CFRP square tube to original EA of intact tube, simple/cost-efficient trigger mechanisms are introduced to avoid catastrophic fracture and induce progressive failure. Both simulation and theoretical analysis are conducted to reveal “how to recover original EA”. First, finite element model with non-linear continuum damage mechanics is developed for tube through experimental validation. Then, two self-contained triggers and two external triggers with different radii are compared. It is found that the inward-splaying trigger (IST) is the best one to improve residual EA (by 64.6%) and crushing load stability (by 174.3%) of perforated tube due to a transition from middle-height fracture to progressive failure. Further, studies on actual hole-environments (i.e., distance/number/relative position) confirm the effectiveness of trigger mechanisms. Although the presence of hole significantly reduces EA, enhancing residual EA of multi-perforated tubes to original EA of intact tube has been perfectly realized. Through failure mechanism analysis, a theoretical model is proposed to better understand main energy-dissipation mechanisms induced by IST. A correlation between theoretical model and simulation explains an increasing EA as trigger radius increases to a certain value, illustrating that average load and EA rely highly on a transition of failure mechanism.