Determination of true stress-strain-curves and normal anisotropy in tensile tests with optical strain measurement

This paper describes a method to measure the flow curve which undergoes necking and normal anisotropy as a function of equivalent strain using an optical measurement system. The flow stress was determined by modifying Siebel and Schwaigerer's model. Normal anisotropy was regarded as a function of equivalent strain. Comparing with the experiment of the stretch forming process, the simulation using improved material properties shows the better strain distribution than the results using conventional material properties in high strain areas.