Identification of material damage in metal sheets

Abstract

Two material models are examined to identify damage propagation in two selected sheet materials: a high-strength steel alloy, ZSte340, and an aluminium alloy, AA5182. The method of continuous uniaxial tension loading and unloading of sheet specimens was adopted for identification of the isotropic material damage parameters. Two damage evolution trends were identified, one linear and the other bilinear. Inverse modelling technique was applied for identification of material parameters. A representative cost function, based on a correlation between the experimental and simulation results obtained, was minimized. An optimization code, relying on response surface methodology, was used to identify the material parameters. Good agreement between the experimental and numerical results from structural simulations of the experiment was obtained up to the onset of diffuse necking. For materials that fracture before a localized necking zone has developed, the proposed methodology enables identification of the critical damage at failure.