A Study on the Effects of Specimen Geometry on Measurement Accuracy of Dynamic Constitutive Properties of Metals Using SHTB

Determination of dynamic tensile response of materials has been a challenge because of experimental difficulty. The split Hopkinson tensile bar (SHTB) is one of the most widely used devices for characterization of various materials under dynamic-tensile loading conditions. Since one-dimensional wave propagation in bars is disturbed by specimens and grips, however, SHTB measurement accuracy may not be guaranteed. This means that the stress–strain curve of the specimen that is calculated using strains at bars may not indicate the real stress–strain relation of the specimen. In this study, simulations for the SHTB test were carried out to investigate the effects of thread pitch, specimen length, specimen diameter, and thread inner diameter of the specimen on the measurement accuracy for two types of metals with medium and high yield strengths. Finally, specimen shapes are recommended for accurate measurement of the stress–strain relation of tantalum and tungsten carbide.