Effect of radial clearance and holes as crush initiators on the crashworthiness performance of bi-tubular profiles

Abstract

The use of bi-tubular structures has gained importance in the design of energy absorption systems for protectionof passengers in train collisions. Therefore, it is critical to improve the crashworthiness performance of bi-tubularprofiles. For this purpose, the effect of cross-section, bi-tubular clearance and holes as crush initiators is eval-uated using finite element simulations. To get reliable outcomes, special emphasis was set on the progressivedamage modelling of aluminum 6063-T5 by a Johnson-Cook (J-C) failure model. During the cross-section study,bi-tubular arrangements based on polygonal and circular cross-section were evaluated by quasi-static com-pression loads. The results indicate that the circular shapes showed better crashworthiness performance or crushforce efficiency (CFE) up to 12.28% respect to a square base structure. A 10.72% improvement in CFE wasobtained when the non-dimensionalized clearance between profiles is increased fromffi20toffi40. Theeffect of holes on crashworthiness performance was evaluated by drilling holes at different locations both in theinner and outer profiles. The results show that the use of holes increased the crush force efficiency and energyabsorption (Ea) capability even more than the effect of clearance alone. Improvements in the order of 2.50% and12.96% for Eaand CFE respectively were computed when holes were placed at the top end of a BC-3 profile witha non-dimensional clearance offfi40. Considering all effects simultaneously, an increase of 24.6% and 26.31%for Eaand CFE respectively was calculated. Finally, an application to a crash buffer in a railway transport systemis considered. Likewise, its improved crashworthiness behavior is presented.