Analysis of the Explosively Driven Expanding Ring Tension Test

The expanding ring tension test has been available in some form for decades, but it remains little utilized compared with shock-induced spallation or the tension Split Hopkinson Pressure Bar test. The explosively driven ring tension test was introduced first, followed by an electromagnetically driven version. The electromagnetically driven ring tension test appears to have overshadowed the explosively driven version; however, the explosively driven expanding ring tension test remains useful in cases where the joule heating of the sample material is undesirable or the use of high voltage power supplies is not practical. In this work, the explosively driven expanding ring tension test was reexamined. Numerical simulations were used to explore the results of different explosive and material geometries. This study found that the sample ring cross-section size should be minimized to minimize stress equilibration time. Tube thickness did not consistently prove to have a strong effect on velocity by itself, but it interacted with the presence of a gap between the driver and the copper tube. The presence of a gap reduced velocity for small charges, but had little impact on larger charges. It appears that great control over radial velocity is possible by fine-tuning the charge size in combination with other factors, though further work is required to develop an optimal experimental configuration.