Numerical simulation of double specimens in split Hopkinson pressure bar testing

Abstract

The split Hopkinson pressure bar (SHPB) is the most commonly used technique to characterize the dynamic behaviour of materials at very high strain rates. However, a classic single specimen test only generates a single stress-strain curve at the average strain rate of the test. This paper proposes three arrangements on the use of double specimens in SHPB compression testing. All waves propagating along the bars have been used to analyse the dynamic behaviour of the specimens. To simulate the test and predict its dynamic performance, an axisymmetric finite element analysis using LS-DYNA was conducted for the experiment using 13 mm bar diameter. The validity of the simulations was checked with experimental data from normal SHPB testing. Based on the simulations, the modified techniques are achievable and at least two stress-strain curves of materials can be extracted without violating the requirement of a valid SHPB test.