A surprising proliferation of detwinning in beta-tin at extreme loading rates and other investigations in compression of condensed matter

Integrating data from dynamic compression experiments of condensed matter across three national laboratories has led to insight

and quantitative calibration of materials strength over many decades of loading rates. For many materials, a single strength model

(such as PTW) is sufficient to capture the flow-stress strain rate relationship which is monotonic. We show here that beta-tin, a

tetragonal metal, exhibits dramatic deviations from this behavior. Naive fitting to a single PTW model is insufficient to capture the

behavior; indeed, such resulting inferred flow stress versus strain exhibits a non-monotonic behavior. We suggest a resolution to this

by proposing that in beta-tin there are important Bauschinger effects arising from favorable conditions for twinning and detwinning.

A simple yield surface model when paired with PTW hardening captures the experimental data.