Energy dissipation characteristics for AA6061 extrusions subjected to hybrid cutting/clamping at impact velocities up to 32 m/s

Abstract Novel deformation modes with favorable energy absorbing properties are critical to improving the grim outcomes associated with traffic collisions, and an understanding of the dynamic performance is necessary for practical implementation. Dynamic testing of AA6061 extrusions in T6 and T4 temper conditions subjected to hybrid cutting/clamping deformation modes was conducted utilizing a pneumatically accelerated testing apparatus with impact velocities ranging from 14 m/s to 32 m/s (1.13 kJ and 5.89 kJ of kinetic energy, respectively). This range replicated the loading conditions associated with traffic accidents and provided new insights into the previously unconsidered dynamic performance of this novel deformation mode. Complementary axial crushing tests were performed to compare the instantaneous force responses and key energy absorption performance metrics between the cutting/clamping mode and current state-of-the-art under impact. Thin-walled ( r o / t ≥ 10 ) circular extrusions subjected to quasi-static, 10-bladed cutting exhibited 50% greater energy absorbing capacity compared to progressive folding. However, the energy absorbing potential was approximately equal for identical extrusions subjected to 22 m/s impact velocities and thick-walled ( r o / t 10 ) extrusions were generally outperformed by the crushing mode. The trend of reduced cutting forces with increasing velocities was attributed to a degrading extrusion/blade interface, confirmed by post-test optical examinations of the cut surfaces, and a corresponding reduction in the associated contact forces. Enhanced analytical and numerical (Eulerian) models were developed which accurately replicated the experimental findings by implementing a newly obtained velocity dependent, degrading friction coefficient with average cumulative errors of 0.084 and 0.102, respectively.