Analysis of weld location effect and thickness ratio on formability of tailor welded blank

Abstract

Stretch forming is an important method in the production of complex parts of a vehicle’s body. The main objective of this study is to analyse the effect of weld zone location coupled with differences in the thickness ratio of tailor welded blank (TWB) sheets on the formability and fracture location in biaxial stretch forming. Samples of TWB made from ST14 material were welded by an Nd/YAG pulsed laser. Standard ball punch testing procedure as well as finite element analysis was carried out to evaluate and hence conform the formability and its characteristics. In conducting simulation to determine fracture/necking occurrence, forming limit diagram criteria were used. The results obtained indicated that fracture takes place in the thin sheet in which, upon forming, the highest strain is exerted. By relocating the weld line toward the thick sheet and hence providing an increase in the thin sheet’s share of TWB along with reduction in the thickness ratio, the generated cup height increases. This is a sign of an increase in formability. Moreover, the results obtained from the simulation, such as location, fracture shape and generated cup height, were compared with the results from experimental measurements of the same parameters, indicating a satisfactory affirmation of the findings.