Forming-limit diagrams of aluminum tailor-welded blank weld material

The current work develops forming-limit diagrams (FLDs) for weld materials in aluminum tailor-welded blanks (TWBs) under biaxial stretching conditions . Aluminum TWBs consist of multiple-thickness and alloy sheet materials wel ded together into a single, variable-thickness blank. The manufacture of TW Bs and their application in automotive body panels requires their constitue nt weld material to deform under biaxial loading during sheet-metal stampin g. The weld geometry is typically nonuniform and relatively small, causing difficulty if one attempts to determine the weld metal FLDs via traditional experimental methods. The subject work primarily relies on theoretical FLD calculation techniques using the Marciniak and Kuczynski (M-K) method. Thi s numerical technique requires the use of material constants and levels of initial material imperfection that have been experimentally determined usin g unique miniature tensile specimens to isolate and characterize the weld m etal. The experimental and numerical work, together with statistical analys is of the level of initial imperfection, allows generation of both an avera ge and safe FLD. The weld metals studied in this work were produced via aut ogeneous gas tungsten are welding of a 1- to 2-mm-thick 5000 series aluminu m alloy sheet.