Dynamic Deformation Behavior of AA2099-T8 Under Compression and Torsion Loads

Abstract

The suitability of aluminum alloys in a vast majority of engineering applications forms the basis for the need to understand the mechanisms responsible for their deformation and failure under various loading conditions. Aluminum AA2099 alloy finds application in fuselage structures that are statically and dynamically loaded, stiffness dominated designs, and in lower wing structures. The fuselage structures and wings of aircraft experience huge damage due to foreign object impacts. AA2099 aluminum alloy has an advantage of high specific strength compared with other alloys in the AA2000, 6000, and 7000 series; this characteristic makes it the material of choice in high performance aerospace structures. In this paper, the dynamic high strain rate impact deformation of AA2099 aluminum alloy under compression and torsion loading conditions using the split Hopkinson pressure and Kolsky torsion bars was performed. Digital image photogrammetric evolution of localized strain in aluminum samples during deformation process using high speed digital camera is reported. Microstructural analysis of deformed aluminum samples was performed using high resolution electron microscopes in order to determine the influence of impact strain rate on localized strain along narrow adiabatic shear bands in the AA2099 aluminum alloys. Results obtained indicate that peak flow stress in the deformed aluminum sample depends on the strain rate at which the deformation test was performed. An increase in impact strain rate results into an increase in the peak flow stress observed in the impacted aluminum sample. The type of adiabatic shear band localized in the aluminum sample also depends on the strain rate at which material was impacted.