Non-proportional tension-shear experiments in a biaxial test facility

This paper discusses the results obtained from experiments on DC06 mild steel with a biaxial test facility. The two presented tests are non-proportional tests consisting of a two stage strain path. First the samples are deformed in the tensile direction after which simple shear deformation is applied. In the one case elastic unloading is applied after the tensile deformation, while in the other case the tensile deformation is directly followed by the simple shear deformation. For the test with elastic unloading a peak in the shear stress appears directly after the strain path change, while in the test without elastic unloading the shear stress gradually increases to a uniform stress-strain curve. The difference in the result is explained with reference to the microstructure evolution.