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#17763, Strength of Nanocrystalline Copper under High Pressures and Ultrahigh Strain Rates

The strength of nanocrystalline materials has been widely studied under high strain rates; however, experimental investigations focused on the pressure-dependent strength of nanocrystalline materials are limited. This study conducts experiments using pressure shear plate experiments to understand the effect of pressures on the strength of nanocrystalline oxygen-free high conductivity (OFHC) copper. A thin film of OFHC copper is sandwiched between two tungsten carbide plates, which are impacted by a tungsten carbide flyer. The free surface normal and transverse particle velocities are measured using heterodyne transverse and normal Photonic Doppler velocimeters. The tungsten carbide anvil material used in this study does not remain elastic at pressures higher than 5 GPa. Therefore, a recently developed hybrid method is used to extract the complete stress-strain behavior of nanocrystalline OFHC copper at high pressures. The stress-strain curve extracted from the experiments shows significant pressure-dependent strength of nanocrystalline OFHC copper. Numerical simulations are performed using existing material models to explore the capabilities of different models in simulating the pressure-dependent strength of materials.

Rushikesh Kabadi   University of Minnesota
Suraj Ravindran   University of Minnesota