Determination of Hugoniot and strength properties of 6061 aluminium alloy under dynamic loading

Abstract

Plate impact experiments have been carried out on 6061 grade aluminium alloy to determine the Hugoniot data points and mechanical failure properties like spall strength and dynamic yield strength at high strain rates. In each experiment, the shock pressure in the target material has been measured using piezo-resistive manganin gauge. In four plate impact experiments, performed at impact velocities of 196 m/s, 288m/s, 490m/s and 649m/s, peak shock pressures of 1.4GPa, 2.2GPa, 3.8GPa and 5.2GPa, respectively, have been generated in the target. To determine the spall strength and dynamic yield strength the velocity history of the free surface of target plate has been obtained employing the velocity interferometer system for any reflector (VISAR). The spall strength derived from the free surface velocity histories corresponding to impact velocities 196m/s, 288m/s and 490m/s are 0.81GPa, 0.96GPa and 1.08 GPa, respectively, with average strain rates ranging between 1.8×10 4/s to 3.7×104/s. The dynamic yield strength calculated from the experimentally derived Hugoniot Elastic Limit (HEL) is found to vary in the range 0.096GPa to 0.12GPa. The value of the spall strength determined in the present work is significantly higher than the quasi static ultimate tensile strength of ∼0.21GPa, whereas the dynamic yield strength remains more or less close to the quasi static value of 0.11GPa. These results indicate that 6061 aluminium alloy displays higher mechanical strength under dynamic loading condition as compared to that under static loading. These high strain rate mechanical properties of 6061 aluminium alloy are also compared with those of 2024 aluminium alloy.Plate impact experiments have been carried out on 6061 grade aluminium alloy to determine the Hugoniot data points and mechanical failure properties like spall strength and dynamic yield strength at high strain rates. In each experiment, the shock pressure in the target material has been measured using piezo-resistive manganin gauge. In four plate impact experiments, performed at impact velocities of 196 m/s, 288m/s, 490m/s and 649m/s, peak shock pressures of 1.4GPa, 2.2GPa, 3.8GPa and 5.2GPa, respectively, have been generated in the target. To determine the spall strength and dynamic yield strength the velocity history of the free surface of target plate has been obtained employing the velocity interferometer system for any reflector (VISAR). The spall strength derived from the free surface velocity histories corresponding to impact velocities 196m/s, 288m/s and 490m/s are 0.81GPa, 0.96GPa and 1.08 GPa, respectively, with average strain rates ranging between 1.8×10 4/s to 3.7×104/s. The dynamic yield str...