A Numerical Investigation on the Crashworthiness Behavior of Hollow, Concrete-Filled, and STF-Filled Aluminum Honeycomb Structures with Varying Cell Wall Thicknesses

Hexagonal honeycomb structures have long been widely utilized as a core feature of crash boxes to enhance passive safety and ensure structural stability in the automotive industry. However, greater operational speeds necessitate superior crashworthiness. In this regard, this study investigated how the energy absorption capacity of honeycomb structures with different cell wall thicknesses can be improved through the use of the filling effect. The study was carried out numerically using Abaqus/Explicit software. The energy absorption capabilities of nine different specimens - hollow, concrete-filled, and STF-filled - with three different wall thicknesses of 0.6, 0.8, and 1.0 mm, were examined. According to the results, the concrete-filled configurations absorbed more energy across all cell wall thicknesses due to the rigidity of the concrete infill. Similarly, the crush force efficiency values of concrete-filled specimens were the highest across all thicknesses. Moreover, hollow structures exhibited the weakest performance in energy absorption. The highest specific energy absorption values were recorded in hollow specimens owing to their low mass density. In STF-filled structures, the energy absorption capacity outweighed the increase in the mass, resulting in a more consistent mass efficiency and higher specific energy absorption compared to concrete-filled specimens. Based on these results, it is demonstrated that STF-filled configurations are recommended for use in the automotive sector where volume constraints are a key consideration in crash boxes. Concrete-filled honeycomb structures are suggested for use in sectors where weight is not a drawback. Lastly, the hollow specimens are recommended for applications in the aerospace industry characterized by weight-limited crash boxes.