Characterisation of out-of-plane shear behaviour of anisotropic sheet metal using double bridge shear test

Accurate characterisation of through-thickness shear resistance is essential for high-quality simulations of sheet metal forming processes such as blanking, riveting, and incremental forming. This resistance is closely linked to the plastic behaviour of materials in the thickness direction, necessitating precise modelling of strain hardening and plastic anisotropy. While simplified assumptions of isotropy or equal in- and out-of-plane shear parameters are often made, advanced approaches rely on crystal plasticity models, which themselves require calibration. This study introduces a novel out-of-plane shear test procedure based on macro-mechanical testing and Digital Image Correlation (DIC) to inversely calibrate the YLD2004-18p yield function. Using a specially designed double-bridge shear specimen, identical in geometry for all tests, the method enables consistent shear testing across all material planes, facilitating direct comparisons of anisotropic behaviour. A sensitivity analysis was used to establish criteria for evaluating test quality and improving future designs. Testing on 2.4 mm thick AA 5754-H22 aluminium alloy reveals that shear responses in the yz and xz planes are 8% and 12% lower than in the xy plane, respectively. The method effectively captures the force-extension response’s sensitivity to variations in out-of-plane shear parameters, enabling a complete characterisation of plastic anisotropy in medium-thick sheet metals. This approach potentially enhances the accuracy of metal forming simulations by providing robust calibration for out-of-plane behaviour.