Axial splitting of circular tubes by means of blast load

This paper presents the results of an experimental investigation on the axial splitting of thin-walled aluminium extrusions by means of blast load. Plastic explosive (PE4) was used to accelerate the circular extrusions onto a cutting die backed by a curved deflector. The apparatus was mounted on a ballistic pendulum to measure the impulse imparted by the explosive. A load cell was used to measure the transient axial load response during the cutting process. Explosive masses, varied from 15 g to 40 g, produced different lengths of cut (28–137 mm) within the extrusion. The specimens, which were made from three grades of aluminium, AA6061-T4, AA6061-T6 and AA6063-T6, had a nominal diameter of 51 mm, a wall thickness of either 1/16″ (1.6 mm) or 1/8″ (3.2 mm) and were 300 mm in length. Similar energy dissipation mechanisms as previously observed for quasi-static and dynamic loading conditions was observed in the blast load testing applications applied in this study. Furthermore, localised plastic deformation and dynamic progressive buckling were also observed which were not noted in previous impact testing conditions. The performance of the circular extrusions was assessed through determination of the mean cutting load, peak cutting load and cutting force efficiency (CFE). The length of cut increased with an increase in charge mass. An increase in material hardness showed a decrease in the overall cut depth and (CFE).

► An extensive experimental study investigating the axial cutting of aluminium extrusions using blast energy to initiate the cutting is presented.
►  To the co-authors' knowledge this is the first completed experimental study on the axial splitting of extrusions by means of blast load.
► Analysis to determine important crashworthiness performance metrics is presented, as a function of blast load.
► Energy dissipation mechanisms that have not been previously observed are presented with the influences of the blast load.