Abstract
This study investigates the crashworthiness performance of double-walled cylindrical tubes reinforced with interior flat-ring circular ribs under axial compression. Finite element simulations were conducted to evaluate how ring number, thickness, and width influence energy absorption (EA), mean crush force (MCF), specific energy absorption (SEA), and deformation patterns. Increasing the number of rings enhances EA and SEA by hinge points for progressive folding, although excessive ring density leads to localized buckling and reduces efficiency. Optimal ring thickness improves EA by promoting progressive folding with minimal mass, whereas overly thick rings reduce the number of plastic hinges and slightly lower SEA. Increasing ring width restricts fold formation and, together with added weight, results in nearly constant SEA despite increasing MCF. These findings demonstrate the potential of interior flat rings as an effective and lightweight design strategy for improving the crashworthiness of thin‑walled energy-absorbing structures.