Impact testing of brittle materials using split Hopkinson pressure bar technique

The high strain-rate compressive behavior of structural materials (ductile and brittle) are quite important, and can be obtained using different experimental techniques, such as falling weight or impacting mass technique, but the accuracy of measurements decreases with the increase of the strain rate. However, the split Hopkinson pressure bar apparatus (SHPB) can provide the solution since, in this case, practical test execution is relatively simple, and interpretation of the test results is relatively straightforward. It is required for a material under test in a SHPB technique to deform homogeneously and at a nearly constant strain rate; therefore this technique is limited for only ductile materials.; Brittle materials (ceramics, rocks) play a vital role in many engineering applications. Therefore, during the last decade there have been numerous developments in the conventional SHPB technique in order to obtain high strain-rate behavior of these materials. Due to certain limitations in the developed techniques, the current work aims at certain modifications in order to facilitate the dynamic testing of brittle materials along with its data analysis.; The first proposed modification relates to the replacement of the cylindrical striker bar of the classical SHPB with a spherical ball. This helps generate a smoothly increasing compressive pulse followed by an unloading tensile one, which was found recommendable in previous works to obtain high strain-rate compressive behavior of brittle materials. The second proposed modification involves the numerical simulation of the SHPB test, aiming at calculating the reflected wave, then comparing it with the measured experimental one. This helps in obtaining the compressive failure strength of brittle materials at different strain-rates in a simple manner.