Research Of Axial Energy Absorption Characteristics Of The Unidirectional CFRP Tapered Circular Tubes

A significant issue associated with composite energy absorbing structures is that the device must crush in a controlled manner.A catastrophic failure at the start of crush will result negligible energy being absorbed.Unstable crush behaviour with the crush load oscillating significantly is also undesirable.To overcome these issues,energy absorbing composite structures often include a triggering mechanism to cause local stress concentration at a specific location.Increased focus has been given to tapered tubes,namely tapered rectangular and conical tubes,which have been found preferable to straight tubes since they do not require crush initiators and they are capable of withstanding oblique impact loads as effectively as axial loads,and appear to have fewer chances to fail via global bending.Aimed at improving energy absorption abilities of the composite tapered circular tube and making composite energy absorbing components achieve the best effect of energy absorbing in engineering applications.The structure optimization of composite tapered circular tube is investigated,and further study the influence of different ratio of conical degree(a)to the number of ply(N)on the specific energy absorption(SEA)and the initial peak impact load(Pinitial),found that with the increase of a/N,SEA and the Pinitial are both reduced;when the a/N exceeds 0.54,the delamination will no longer occur.Finally,the composite tapered circular tube is manufactured according to the optimization results,the optimal results are validated by experiments.Optimization results show that:compared to the initial model,the SAE increases 15.6%(from 67.9 J/g to 78.50 J/g),the Pinitial decreases 51.8%(from 52.3kn to 25.2kn)and the mass decreases 22.4%(from 55.3g to 42.9g).Compared with the straight tube before optimization,the optimized tapered tube not only has the mode-I crack propagation,but also has the mixed mode-?/? crack propagations,and the energy dissipation is more diverse.In addition,unlike the slender everted flaps of the straight tube,the everted flaps of the optimized taper tube will curve and accumulate in the vicinity of the neutral surface,the bending deformation of the flap and the friction between them can absorb more energy.