New approach for determination of strain rate sensitivity of mild steel dc01 under stack compression and uniaxial tensile test

Deformation under uniaxial tensile loading with using Digital Image Correlations (DIC) is the easiest way to analyze the material behavior in sheet metal forming. In order to determine the plastic parameters such as hardening, anisotropy and strain rate sensitivity at higher strain level, equi-biaxial stress state is prerequisite. As reported in the literature, Bulge tests are frequently used for this purpose, but in this work, stack compression test is used as an alternative. In this experiment, deformation in the middle layer where the friction effect is the lowest was monitored using two pairs of DIC systems in rolling and transversal directions. Uniaxial tensile tests as well as stack compression tests were performed on mild ferritic steel DC01 at different strain rates, from 0.001 𝑠𝑠−1 to 10 𝑠𝑠−1. Strain rate sensitivity parameter was investigated at different level of strains for both experiments and strain rate sensitivity profiles were obtained. Results show a decrease of material strain rate sensitivity with increasing the true strain.