Compressive Viscoplastic Response of 6082-T6 and 7075-T6 Aluminium Alloys Under Wide Range of Strain Rate at Room Temperature: Experiments and Modelling

In this work, the viscoplastic behaviour of 6082-T6 and 7075-T6 aluminium alloys is examined over a wide range of strain rates. Three different testing techniques were applied to this investigation: low-rate experiments were performed using a regular servo-hydraulic testing machine, high-rate tests were conducted using a split Hopkinson bar apparatus and very-high-rate experiments were carried out using a miniaturised direct impact test arrangement. The latter testing set-up allowed for the characterisation of material flow at strain rates up to . These experimental results showed a sharp increase in the rate sensitivity of the materials once a threshold loading rate of is exceeded. This behaviour may be attributed to the presence of viscous drag on high-velocity dislocation motion. In addition, the thermo-viscoplastic behaviour of the 6082-T6 and 7075-T6 aluminium alloys was analytically described using the extended RusinekKlepaczko model of viscous drag effects. Satisfactory correlation was observed between the experiments and the constitutive model results over the entire range of strain rates studied,