Formability assessment of FCC aluminum alloy sheet by using elastic/crystalline viscoplastic finite element analysis

Abstract

This study looks at the influence of crystallographic texture on the formability of FCC aluminum sheet metal using our elastic/crystalline viscoplastic finite element (FE) analysis code “ROBUST-CRYSTAL”. First, the crystallographic textures of Al–2.5% Mg aluminum alloy generated by employing different annealing temperatures were obtained by X-ray diffraction and orientation distribution function (ODF) analyses. The measured ODF results revealed clearly different textures of sheets, featured by orientation fibers, skeleton lines and selected orientations in Euler angle coordinate space, which can be related to plastic anisotropy. The orientation probability assignment method was used in FE modeling. The orientations determined from the measured ODF results were assigned to FE integration points. A large number of integration points, which represent crystallites and can rotate individually, are employed to represent textures of the sheet metals, which take into account the initial and evolutional plastic anisotropy without introducing Taylor or Sachs homogenization assumption. An actual sheet metal forming process, VDI benchmark problem, was adopted to assess the texture effects on strain localization and failure. It was confirmed by comparison with experimental results that our crystalline plasticity FE code could predict strain localization and assess formability with good accuracy.