The study on energy absorption of foam-filled tube subjected to impact

Metallic tubes are wide used in many engineering applications such as building structures and automotives. In particular, the automotive body is consisted of various shapes of metal tubes i.e. square and circular tubes as example. These elements are required to have less weight as much as possible in order to reduce fuel consumption. Therefore, the study on how to reduce their weight but maintain their strength has been a main aim for crashworthiness study since decades. This study if mainly focused on the collapse mechanism and energy absorption capacity of tubes. In general, there are many techniques to enhance the energy absorption capacity of structure under impact. The foam filling is one of those choices. In addition, foam filling is also a technique that can increase the crashworthy with less weight increment. This results in better specific energy absorption of structure.
This research is aimed to investigate the energy absorption capacity of foam-filled tube under axial impact. The energy absorption characteristic and mode of collapse are also observed and discussed. This study used polyurethane foam (PU foam) with density between 50-300 kg/m3 fill in aluminum and steel tubes, rectangular, square and round sections. The consideration parameters are wall thickness, shape and foam density. The experimental result is compared with FE simulation which is done using ABAQUS/Explicit. The experiment is conducted on quasi-static and impact testing. The results revealed that, both, steel and aluminum tubes can absorb higher energy as the foam density increases. However, the specific energy absorption tends to decreased at higher foam density due to the influence of mass. The observation of collapse mode indicates that number of collapse fold, both steel and aluminum tubes, tends to increase as the density is increasing. The majority of empty steel tube is found to fail in symmetric mode and change to asymmetric mode after filled with high density foam. Considering the effect of D/t, it is found that as the value of D/t is increasing, the collapse mode of aluminum tubes id changing from asymmetric to symmetric modes. The comparison of experimental and FEA results indicate that they are in good agreement. However, the prediction value from FEA is slightly higher than the experiment due to some assumptions and imperfection of experimental specimens.