Experimental and numerical investigation of pulse-shaped split Hopkinson pressure bar test

Abstract

Employing a proper pulse shaper in the conventional split Hopkinson pressure bar (SHPB) test helps to achieve dynamic equilibrium condition and to fulfill a constant strain rate condition in the test specimen. To this end, the parameters affecting the incident pulse shape, i.e., pulse shaper thickness, pulse shaper diameter, striker bar length and striker bar velocity are experimentally studied. Moreover, simulation results, validated by experimental data together with wave propagation analysis, are exploited to provide general guidelines to properly design a pulse shaper. It is recommended to use a relatively large diameter pulse shaper for testing work-hardening materials. Also, for different test conditions, e.g., striker bar velocity, it is recommended to scale the pulse shaper thickness and cross-sectional area proportional to the striker bar velocity. Employing these guidelines considerably reduce the try and error process for selecting proper pulse shaper. Finally, to show the effectiveness of the proposed guidelines in practice, SHPB experiments on copper and cast iron specimens are performed. The results show that the variation of strain rate in the specimens is reduced significantly when a proper pulse shaper is employed.