Crashworthiness behavior of thin-walled bimaterial tubes under axial collapse

Abstract

This study aims to investigate the crashworthiness performance of thin-walled bi-material tubes (bi-tubes) subjected to axial impact loading. Different tube diameter, wall thickness and material combination for external and internal tubular layers are examined in order to assess their effect on energy absorption (EA) capacity and plastic collapse initiation. At first, quasi-static experimental tests are conducted for four axially compressed bi-tubular specimens, while at next finite element (FE) numerical simulations are carried out utilizing non-linear explicit dynamic LS-DYNA code. The numerical results are initially validated against the experimental ones and both are then considered for assessing the crashworthiness performance of the examined bi-tubes by evaluating the crashworthiness indicators and the occurred failure mode. Both experiments and simulations showed a mixed deformation mode during plastic collapse, while greater wall thickness and diameter resulted in increased absorbed energy and peak crushing force (PCF). Finally, bi-tubes consisted of harder outer layer and softer inner one revealed increased EA due to the adhesion maintenance between the two layers during collapse which results in a more efficient energy-absorbing mechanism, while in contrast the bi-tubular configuration of opposite inner-outer material combination reacts to lower PCF facilitating plastic collapse initiation.