Spall and Damage in Convergent Geometry Using Pulsed Power

The ability of pulsed-power to magnetically accelerate and drive high-precision liner-target implosions facilitates studies of material properties such as damage in cylindrically convergent geometry. Spallation damage experiments are usually conducted in a planar geometry, allowing for one-dimensional analysis of evolution of failure characteristics. Cylindrical experiments allow for a careful analysis of the effect of convergence and two-dimensional strains and shear stresses on the spallation profile of a material. This paper reports on a series of recent experiments to provide data describing the onset of failure of a well-characterized material (aluminum) in a cylindrically convergent geometry. Experimental data includes post-shot collection of the damaged target for subsequent metallographic analysis, dynamic VISAR velocimetry to infer the target material spallation strength and damage model parameters, and transverse radial radiography to assess drive and impact symmetry. This data is used to develop and validate damage and failure models. The theoretical basis, designs and results are presented for these experiments using explosively-driven pulsed power facilities.