New attempt to wrinkling behavior analysis of tailor welded blanks during the deep drawing process

Tailor welded blanks (TWBs) are steel sheets of different characteristics welded into a single flat blank prior to pressing in order to achieve the optimal material arrangement and weight reduction for cars, and to increase process efficiency and machine flexibility. The problem in regard with these blanks is their low formability, which defects like wrinkling occur prematurely. Developing a model to assess the wrinkling initiation of these blanks during forming processes enables one to arrange the forming parameters to enhance the formability. In this research, wall wrinkling tendency of a TWB consisted of interstitial free (IF) steels with different thicknesses (0.8 and 1.2 mm) was analyzed analytically, numerically and experimentally. Due to more formability of thin segment with respect to weld and thick segments which results in deflection of the thin segment, the principal stress directions were assumed to be deviated from the principal curvature axes. “Autogrid” software was applied to measure the geometrical data and strains during the experiments. The predicted results about punch stroke value and critical strain at onset of wrinkling were in good agreement with experimental results. The results also showed that wrinkle waves just formed in thin segment of TWB, and wrinkling initiated by development of three wrinkle waves.

► Wall wrinkling behavior of TWBs with TR > 1 was analyzed analytically and numerically. ► The onset of wrinkling was determined by using bifurcation method. ► Due to deflection of thin segment, the effect of shear stresses was considered.