Shock and mechanical response of 2139-T8 aluminum

Abstract

Planar shock wave experiments were performed on 2139-T8 aluminum to determine its response to dynamic loading. A Hugoniot was determined to 12 GPa. Lateral stress measurements along with a study of the release behavior indicate that this material retains its shear strength to at least 8 GPa. Spall strength was measured for ∼1 μs compressive pulse durations and found to be approximately constant at 1.45 GPa up to shock stresses of 10 GPa. Beyond 10 GPa, spall strength decreases considerably. Uniaxial stress compression tests were conducted with a servo-hydraulic load frame and the Kolsky bar method to obtain stress-strain curves at strain-rates from 0.001/s to 85k/s. This data shows the material is rate independent. The shock experiments were simulated using a Lagrangian finite element code using a polynomial equation of state, the Johnson-Cook strength law, and the Cochran and Banner spall model. The ability of the simulations to reproduce the experimentally measured data is mixed, with significant deviations in modeling the plastic wave front, plastic release, and the spall pull-back signals.