An Experimental and Numerical Study of Deformation Behavior of Steels in Biaxial Tensile Tests

Lightweighting materials are increasingly being used by automotive companies as sheet metal components to meet fuel economy targets by the year 2025. Consequently, accurate material model data need to be developed by applying biaxial strain paths with cross-shaped specimens, since traditional uniaxial stress-strain data cannot capture the deformation behavior in complex forming operations. This paper discusses the development of finite element models and verification of these models against experimental measurements. Such verification is the first step in developing procedures for making an optimum cross-shaped specimen design. Computed results of deformation, strain profile, and von Mises plastic strain in two different specimens agree with experimentally measured values along critical paths in the specimens. In addition, simulated results predict correctly the eventual failure location in the samples. Detailed analyses also suggest that specimen thickness has an influence on the eventual mode of failure. Further studies are being conducted to confirm this conclusion.