Optimised design of nested oblong tube energy absorbers under lateral impact loading

Abstract

Abstract.Dynamic lateral crushing of mild steel (DIN 2393) nested tube systems was conducted using a ZWICK ROELL impact tester. The tests were performed with impact velocities ranging between 3 and 5 m/s, achieved using a fixed mass impinging onto the specimens under the influence of gravity. The various nested tube systems consisted of one standard and one optimised design. Their crushing behaviour and energy absorption capabilities were obtained and analysed.In addition to the experimental work, numerical simulations using the explicit code LS-DYNA were conducted; boundary conditions matching those observed in experiments were applied to the models.Results from the numerical method were compared against those obtained from experiments. An overprediction in force-deflection responses was obtained from the numerical code. An attempt was made to explain this inconsistency on the basis of the formation of plastic hinges and the validity of strain rate parameters used in the Cowper Symonds relation. It was found that the optimised energy absorbers exhibited a more desirable force-deflection response than their standard counterparts due to a simple design modification which was incorporated in the optimised design.

Metallic tube type energy absorbers: A synopsis

“…Similar to the above author's work, Olabi et al [28] analysed both experimentally and numerically the dynamic lateral compression of elongated circular tubes (oblong tubes). The dynamic lateral crushing of mild steel (DIN 2393) nested tube systems was conducted using a ZWICK ROELL impact tester.…”

Contraction process of the circular tubes on the conical die: Theory and experiment

“…Based on the minimum principle in plasticity, differentiating the maximum value of axial load at the end of fifth stage yields R 2 = 3t 5:end t 3:end À 2R p + t 4:end À Á + t 5:end cos a t 3:end cos a À 4 ð Þ + 2R p À 3t 4:end  à + ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi 8R 2 p t 5:end 2R p + 3t 3:end ( cos a À 1) + t 4:end ( cos a À 3) + 2t 5 …”

Optimizing the layout of nested three-tube structures in quasi-static axial collapse

“…They also studied lateral crushing of circular and non-circular tube systems under quasi-static conditions experimentally and numerically [12], and characteristics of the tubes were analyzed via compression-displacement curves. Olabi et al investigated optimized design of nested circular and oblong steel tube energy absorbers under lateral impact loading [13,14]. The steel structures were loaded dynamically by a falling impactor at 3-5 m/s velocities; besides, energy absorption characteristics were simulated by LS-Dyna code.…”