Back stress quantification in heterostructured metals: a comparative study of tension-compression and loading-unloading-reloading tests

The Bauschinger effect, characterized by a reduction in yield stress upon load reversal, plays a critical role in both springback prediction and the understanding of back stress-mediated strengthening in emerging heterostructured materials. In this study, we systematically investigate the differences between tension-compression and loading-unloading-reloading tests in quantifying back stress by employing both homogeneous and heterostructured materials. This work provides critical insights into the mechanistic interpretation of the Bauschinger effect and establishes the validity of loading-unloading-reloading tensile testing for assessing back stress evolution in heterostructured metals.