Maximized Energy Absorption and an Investigation on Practical Limitations for the Axial Cutting and Hybrid Cutting/Clamping Deformation Modes

The axial cutting deformation mode is a novel alternative to progressive folding, the current state-of-the-art, where the cutting scheme exhibits more favorable mechanical performance. By splitting the extrusion into multiple evenly spaced and near-identical petals a highly consistent force response can be achieved. Maximizing the energy absorbing capacity of a sacrificial energy absorber is a fundamental design challenge in the field of crashworthiness. Generating hybrid deformation modes by simultaneously combining multiple deformation mechanisms into a single safety system is a promising technique to achieve high capacity energy dissipation. However, these systems tend to be susceptible to transitioning deformation modes (e.g. from progressive folding to global bending) since the sacrificial material is often loaded at or near its capacity. The impetus of this research was to identify the ceiling on the mechanical performance of the axial cutting and hybrid cutting/clamping modes, particularly in terms of the maximum number of blades which can be reliably implemented. Conventional 6061-series aluminum extrusions were subjected to these deformation modes utilizing previously untested 12 to 14-bladed cutting tools. The parametric scope considered multiple extrusion geometries and material temper conditions. The mean force for the 12-bladed cutting/clamping mode was on average approximately 20 % greater in comparison to equivalent geometries subjected to axial crushing. The hybrid cutting/clamping mode resulted in approximately 10 % more energy absorption in T6 tempered extrusions when compared to pure cutting.