Comparison of determination of biaxial true stress – true strain curves by the use of plane strain compression test and bulge test

Abstract

The true stress-strain curve of the common uniaxial tensile test delivers data only within the uniform elongation. Beyond the instability point, the flow curve is usually extrapolated by different the mathematical approaches. Due to the different mathematical approaches, the extrapolated flow curve shows different curve shapes. A more accurate extrapolation can be achieved with the help of a different test, which enables an experimental determination of true stress - true strain curves at higher strain values. In this paper the biaxial true stress - true strain curves determined with the aid of a newly developed plane strain compression test for thin sheets are presented and compared with the results of the bulge test for the same material.