Mechanical Performance of Circular AA6061-T6 Extrusions Under Axial Cutting Deformation

Dynamic and quasi-static axial cutting of circular AA6061-T6 extrusions with variable instantaneous wall thickness in the axial direction was completed to investigate the capability of controlling the load/displacement responses of the extrusions. Circular specimens considered for this research had an original nominal wall thickness of 3.175 mm, an external diameter of 50.8 mm, and a tube length of 300 mm. Variations of the wall thickness were completed by material removal of the extrusions using a CNC machine. Specially designed cutters having a block height of 20 mm, a blade tip width of 1.0 mm and a blade shoulder width of 3.0 mm were employed to generate the axial cutting deformation mode. Either one or two cutters were selected to initiate a single or dual cutting deformation. A curved deflector with a profile radius of 50.8 mm was used to flare the cut petalled sidewalk and facilitate the cutting system. Results from the impact tests illustrated that an initial peak cutting force with a magnitude of 1.08-1.99 times higher than that for the quasi-static loading was needed to initiate the cutting deformation mode. After this transient cutting stage, the load/displacement responses were observed to be similar to that from the quasi-static tests except for some slight fluctuations resulting from material fractures which occurred on the petalled sidewalls. The mean cutting force from the dynamic tests was determined to be 0.92-1.10 times that from the quasi-static tests for both single and dual cutting deformation modes. Control of load versus displacement responses of the extrusions under both impact and quasi-static cutting conditions was accomplished through the variation of the wall thickness along the axial direction of extrusions and/or adopting the dual cutting deformation.