Influence of weld characteristics on numerically predicted deformation behavior of aluminum tailor-welded blanks

摘要

The automotive industry is continuously investigating means for producing lighter-weight vehicles in order to improve fuel efficiency and reduce emissions. Lightweight materials, such as aluminum, are often used to replace steel in automotive body structures, such as hoods, decklids, fenders, and their corresponding reinforcements. To further reduce weight and improve stiffness, sheets of different gages and/or properties are welded together prior to stamping to form "tailored" blanks. The presence of the weld and the gage mismatch in these blanks, often result in premature failure, which can be expressed as a shift in the forming limit diagram. Several process variables affect this change in deformation behavior including the welding process used to join the blanks, the weld orientation, the weld geometry, and the mechanical properties of the weld and the base materials. Developing an understanding of the deformation behavior of tailor-welded blanks has been the focus of many studies. However, to improve computational efficiency, researchers have, in general, ignored the weld line geometry and properties when modelling tailor-welded blank forming, even though different welding techniques produce welds with different widths, profiles, and properties. Therefore, this paper discusses the results of investigating the effects of weld material properties and weld geometry on deformation behavior in the vicinity of the weld line, and describes the different approaches that were used to represent the weld geometry. The findings indicate that if material behavior near the weld line is required, then shell element models are insufficient and models including weld material properties and/or weld geometry should be used.