A Review of Cruciform Biaxial Tensile Testing of Sheet Metals

Biaxial testing technology enables the comprehensive study of sheet-forming performance and has great potential developmental and commercial value. This work is a review of cruciform biaxial tensile testing technology, as used in actual production, and provides evidence for sheet metal forming processes to describe problems that remain to be solved and to suggest new ideas for future study. The testing apparatus including cruciform biaxial tensile testing machines, heating devices, and optical strain measurement systems are discussed. Some typical descriptions of material tests to achieve stress and strain curves, the yield loci, and limit strains relating to both ambient and high temperatures are also presented. Moreover, finite element modeling as applied to specimen design, material deformation prediction, and material model determination is investigated. Furthermore, the sample design methods and a few examples are summarized in spite of the lack of geometry standard. Future prospects are mainly focused on the establishment of specimen geometry standard, reverse modeling technique for high temperature tests, and the actual applications of biaxial tensile tests.