Evaluation of axially-crushed cellular truss structures for crashworthiness

摘要

Thin-walled tubes have long been used as energy absorbing structures, owing to their high specific energy absorption (SEA) capacity. But, they are associated with substantial high values of peak crush force (PCF). A high PCF results in a high deceleration pulse on the critical components and/or the passengers. This poses serious safety concerns. Even the use of triggers and grooves do not reduce the PCF considerably. To achieve improvement on the safety aspect, the research on the crashworthiness of the cellular truss structures was conducted in this paper. Finite element simulation model was developed by using ABAQUS/Explicit software and validated experimentally with structures fabricated through additive manufacturing. The truss structures were compared to the thin-walled tubes on the basis of their mass, SEA and PCF values. For an equal amount of energy absorption, while the truss structures had a higher mass, the PCFs were lowered significantly. The PCFs decreased at a rate 1.5 to 4.5 times faster than the corresponding decrease in SEAs. The example of the crash box showed that the drop in PCF due to the use of truss structure resulted in a reduction of around 5g deceleration at the cost of 1 kg of additional mass.