Crush Characteristics of AA6061-T6 Round Tubes During a Cutting Deformation Mode

This research deals with both experimental testing and numerical modeling of the cutting deformation associated with aluminum AA6061-T6 round extrusions as possible energy absorbing structures. For the experimental portion of this research, round extruded specimens of length 200 mm with a nominal wall thickness of 3.175 mm and an external diameter of 50.8 mm were considered. A heat treated 4140 steel alloy cutter was designed and manufactured with four cutting blades of approximate average thickness of 1.00 mm to penetrate through the round AA6061-T6 extrusions. Results from the experimental tests showed that the cutting deformation mode exhibited a high average crush force efficiency of 0.95 compared to average values of 0.66 and 0.20 for progressive folding and global bending deformation modes respectively. An almost constant cutting force was observed during the cutting deformation process. To better understand the contributions to energy absorption through material deformation a numerical model was developed and simulated using LS-DYNA employing an Eulerian finite element formulation to overcome numerical instabilities associated with massive mesh distortion. Good predictive capabilities of the developed numerical model were observed and were important towards the understanding of the contribution of deformation mechanisms and friction towards the force/displacement response of the extrusions in the cutting deformation mode.