This Letter focuses on the plastic response of a material, treated as a fluid, when subjected to sliding interactions. The analysis couples momentum conservation with material flow laws to predict velocity and strain-rate profiles that develop during sliding. The profiles depend on the strain-rate sensitivity. The spatial extent of the deformed zone is determined by strain-rate sensitivity, strength parameters, and the imposed sliding velocity.

A Series of dynamic friction experiments has been conducted at the Atlas Pulsed Power Facility. Pulsed currents in excess of 21 MAmps were delivered to a cylindrical liner in about 15 ms. The liner was accelerated to km/s velocities and symmetrically impacted a hollow Ta/Al/Ta target. Initial analysis indicates that the machine performed to within a few percent of the design specifications. The primary diagnostic for these experiments was three radiographic lines-of-sight to look at thin gold wires embedded within the Al piece of the target. The magnitude of the displacement and the amount of distortion of the wires near the material interface is used as a measure of the dynamic frictional forces occurring there. Data are being compared to a theoretical dynamic friction model for high sliding velocities. The model is based on molecular dynamics simulations and predicts an inverse power law dependence of frictional forces at very high sliding velocities.