Mechanical characterization and constitutive modeling of aluminum AA1050 subjected to high strain-rates

This work develops an elastic-viscoplastic constitutive formulation to the mechanical behavior of polycrystalline FCC metals subjected to high-strain-rate cold deformation, with application to aluminum AA1050. Following a phenomenological approach, the model can account for important macroscopic features related to the mechanical response of ductile metals subjected to high-velocity plastic deformations, such as: (i) strain-hardening; (ii) strain-rate-hardening; and (iii) instantaneous flow stress rate-sensitivity. As a novelty of this proposal, memory effects corresponding to past strain-rate history are considered to affect both the level and rate of material hardening. Another new aspect is the phenomenological representation of both the thermal activation and dislocation drag mechanisms influencing the instantaneous flow stress response. The model calibration and its validation are performed based upon experimental data for commercial pure aluminum AA1050 for wide strain and strain-rate ranges. In comparison with experiments, the proposed model provides suitable predictions for both continuous and sequential compression tests. Overall, due to its relative simplicity and constitutive capabilities, the proposed model proves to be a potential constitutive alternative to simulate engineering problems involving dynamic plastic deformations.