In Situ and Postmortem Measures of Damage in Polymers at High Strain-Rates

Significant progress has been made in the in situ and postmortem observations of the dynamic tensile failure and damage evolution of a range of polymers employing Taylor anvil and Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) loading. The classic Taylor anvil technique involves impacting a right-cylinder against a semi-infinite rigid anvil to access large compressive strains (>1) and high strain-rates (>1,000/s). The Dyn-Ten-Ext technique probes the tensile response of materials at large strains (>1) and high strain-rates (>1,000/s) by firing projectiles through a conical die. Depending on the extrusion ratios and velocities damage varies from bulk deformation with substantial internal damage, to a stable jet with finite particulation, to catastrophic fragmentation. Postmortem sectioning and X-ray computed tomography access mechanisms of internal damage inception and progression. In situ measurements of damage are made with the impact system for ultrafast synchrotron experiments (IMPULSE) using the advanced imaging and X-ray diffraction methods available at the Advanced Photon Source. The time resolved phase-contrast imaging elucidates the evolution of damage features during dynamic loading that is observed in post mortem sectioning and tomography.