The results from an experimental and computational study on the effects of specimen size and shape on split Hopkinson pressure bar (SHPB) testing are presented. The effects of the L/D ratio (length L divided by diameter D) along with specimen shape (cylindrical versus square prismatic) were investigated. Even though specimens having a circular cylindrical cross-section are traditionally used in SHPB testing, a square cross-section specimen has advantages associated with in situ imaging of the specimen side surfaces during stress wave propagation. The results presented here show a strong correlation in specimen response between the two types of specimens. Different ranges of L/D ratios are recommended for obtaining stiffness and strength data at near constant strain rates.
