Energy absorption ability of crush boxes filled with strut based and TPMS lattice structures

In the automotive industry, crush box structures are integral components placed between the vehicle bumper and front rail, designed to absorb energy during collisions and thereby mitigate injuries and fatalities. These structures play a critical role in vehicle safety by dissipating kinetic energy and reducing the impact forces transmitted to occupants. The literature has explored various aspects of crush box designs, including different geometries, materials, filler designs, filler materials, and loading conditions, to enhance the energy absorption capabilities of these structures. Lattice structures, which are composed of repeating unit cells, have gained significant attention in both engineering and biomedical applications due to their remarkable properties, including high energy absorption capacity, sound insulation, and thermal management abilities. These properties make lattice structures ideal candidates for improving the performance of crush boxes. This study investigates the effect of incorporating different lattice structures-Body-centered cubic (BCC), face-centered cubic (FCC), gyroid, diamond, and primitive-as filler materials in square crush boxes subjected to axial loading. The primary aim is to improve the energy absorption ability of these crush boxes. Aluminum 6063 square tubes, integrated with PolyJet-printed lattice fillers, were subjected to axial quasi-static loading conditions. The energy absorption performance was quantified using specific energy absorption (SEA), maximum peak load, crush force efficiency (CFE), and mean crush force (MCF) indexes. The results demonstrated that the addition of lattice fillers significantly enhances the crushing performance of the crush boxes compared to empty tubes. Among the tested lattice topologies, the gyroid structure exhibited the most superior performance, achieving 63.9% higher crush force efficiency (CFE) and 67.6% higher specific energy absorption (SEA) compared to empty tubes. This indicates that the gyroid lattice structure is particularly effective at improving the energy absorption characteristics of crush boxes.