Characterization of Metal Foil in Anisotropic Fracture Behavior with Dynamic Tests 2018-01-0108

Metal foil is a widely used material in the automobile industry, which not only is the honeycomb barrier material but is also used as current collectors in Li-ion batteries. Plenty of studies proved that the mechanical property of the metal foil is quite different from that of the metal sheet because of the size effect on microscopic scale, as the metal foil shows a larger fracture stress and a lower ductility than the metal sheet. Meanwhile, the fracture behavior and accurate constitutive model of the metal foil with the consideration of the strain rate effect are widely concerned in further studies of battery safety and the honeycomb. This article conducted experiments on 8011H18 aluminum foil, aiming to explore the quasi-static and dynamic tension testing method and the anisotropic mechanical behavior of the very thin foil. Two metal foil dog-bone specimens and three types of notched specimens were tested with a strain rate ranging from 2 × 10⁻⁴/s to 40/s and various stress states. It was shown that the metal foil has an obvious anisotropic behavior and the stress level increases with the strain rate. An anisotropic material model, which combined the Yld2000-2d plasticity model and the rate-dependent plasticity framework, was used to describe the mechanical behavior of the metal foil. Meanwhile, the fracture behavior of the metal foil was calibrated with an anisotropic fracture initiation model. The results of the constitutive model reproduced the strain rate effect and the anisotropic behavior of the metal foil, which have a good agreement with the experimental data.