Experimental and numerical assessment of Tailor-Welded Blanks formability

A Tailor-Welded Blank (TWB) consists of steels of different thicknesses, strength types welded together to produce a single blank prior to the forming process. TWBs offer several notable benefits including decreased part weight, reduced manufacturing costs, increased environmental friendliness, and improved dimensional consistency. In order to take advantage of these benefits, however, designers need to overcome the formability of TWBs and be able to accurately predict unique characteristics related to TWB forming early in the design process. In this paper, a numerical model to predict the forming height dome and a specific forming curve of TWBs is presented. Finite element analyses of standard TWB forming tests (Nakazima) were performed in Arcelor Mittal Auto Application Research Center to determine the interaction between the weaker and the stronger materials. One of the most important aspects in the instability analysis is the problem of the measurement of the critical strain at necking. A new method is presented in this paper based on the analysis of the major strain rate using the discrete Gaussian convolution. A comparison of numerical and experimental results highlights a good agreement. The numerical approach offers a considerable gain to obtain specific FLC for all configurations.