High Rate Tensile Strength Measurements of Frangible Bullets Using a Kolsky Bar
S P. Mates, Richard L. Rhorer, S Banovic, Eric P. Whitenton, Richard J. Fields
The tensile strength of frangible bullets is measured by a high rate diametral compression test (DCT) performed with a Kolsky Bar. Frangible bullets, meant to disintegrate on impact by brittle failure, also exhibit significant plasticity in compression. As a result, the elastic stress analysis usually used for the DCT cannot accurately deduce a tensile strength from the test results. To account for plasticity effects, finite element analysis is used to calculate the stress throughout the disk as it deforms under diametral loading prior to failure. Two cases are examined. The first involves a standard disk-shaped sample, and the second involves a disk with its contact points pre-flattened to reduce the amount of plastic strain prior to failure. With the standard sample, plastic flow produces tensile stresses at failure that are 80% larger than those predicted by the usual elastic analysis of the DCT. Stresses at failure with the pre-flattened sample are 30% lower than the elastic prediction, owing to load distribution and three dimensional effects. Results with the pre-flattened sample are considered more reliable since the finite element calculation does not account for crushing damage which is observed at the contacts points with the standard sample but is avoided with the pre-flattened sample.
Proceedings of the Society of Experimental Mechanics Annual Conference
, Rhorer, R.
, Banovic, S.
, Whitenton, E.
and Fields, R.
High Rate Tensile Strength Measurements of Frangible Bullets Using a Kolsky Bar, Proceedings of the Society of Experimental Mechanics Annual Conference, St. Louis, MO, USA
(Accessed December 4, 2023)