Evaluation of Effective Paramters on Formability of TWB

Formability of automotive friction stir welded TWB (tailor welded blank) sheets is numerically investigated in biaxial stretching based on hemispherical dome stretch (HDS) test in four automotive sheets of Aluminum alloy 6111-T4, 5083-H18, 5083-O and DP590 steel, having different thicknesses. The effects of the weld zone modeling and the thickness ratio on formability are evaluated. In order to carry out the numerical simulations, mechanical properties are considered according to Chung et al. [11] experimental results. von-Mises and Hill’48 quadratic yield functions are used to compare the isotropic and anisotropic behaviors of the used sheets. In order to simplify the problem, the anisotropy of the weld zone is ignored. The FEM results are compared with experimental results of [11]. Anisotropic assumption for base materials and varying thickness for the weld zone give more accurate prediction. Numerical results are in good
agreement with the experimental results. Failure onset locations and patterns are accurate. Since the formability is dependent on the stress concentration, asymmetric distribution of strength and complexity of weld zone properties, the thickness ratio in TWB affect formability.