Low-density polyethylene extreme deformation in laboratory ballistic launchers

The paper is devoted to the study of high-speed extrusion of polyethylene in the conical nozzle of a ballistic laboratory launcher. The acceleration of the assembly, consisting of a cylindrical polyethylene piston and two metal cylinders located in front of and behind it, is carried out using a compressed gas ballistic launcher. For a theoretical description of the assembly acceleration and extrusion of polyethylene, a quasi-one-dimensional mathematical model is utilized. Polyethylene is considered as a viscoplastic fluid. Equations are solved by a numerical method on a moving mesh. The two-dimensional axisymmetric problem is solved using ANSYS Autodyn package. Experimental studies are carried out on a ballistic laboratory setup, accelerating the assembly to speeds of 572 m/s and 900 m/s. Good agreement of theoretical and experimental results are shown. As a result of the study, it was shown that the speed of the front metal element increases one and a half times compared with the speed of entry. The analysis of the possibility of accelerating the projectile was performed using the effect of extrusion and without it. It was shown that extrusion gives an increase in speed for projectiles of small mass.The paper is devoted to the study of high-speed extrusion of polyethylene in the conical nozzle of a ballistic laboratory launcher. The acceleration of the assembly, consisting of a cylindrical polyethylene piston and two metal cylinders located in front of and behind it, is carried out using a compressed gas ballistic launcher. For a theoretical description of the assembly acceleration and extrusion of polyethylene, a quasi-one-dimensional mathematical model is utilized. Polyethylene is considered as a viscoplastic fluid. Equations are solved by a numerical method on a moving mesh. The two-dimensional axisymmetric problem is solved using ANSYS Autodyn package. Experimental studies are carried out on a ballistic laboratory setup, accelerating the assembly to speeds of 572 m/s and 900 m/s. Good agreement of theoretical and experimental results are shown. As a result of the study, it was shown that the speed of the front metal element increases one and a half times compared with the speed of entry. The anal...