High strain rate tensile testing using a split Hopkinson pressure bar apparatus

A specially-designed specimen is proposed to investigate the tensile response of metals at high strain rates. This specimen may be directly used in a conventional split Hopkinson pressure bar system, thereby overcoming difficulties related to the gripping of traditional tensile specimens in dynamic testing. The specimen geometry has been optimized using finite element analysis. The dominant stress state in the specimen gage section is transverse plane strain. Explicit expressions are given to obtain the equivalent uniaxial stress-strain curve from the force and displacement measurements at the specimen boundaries. Quasi-static experiments have been carried and compared with standard uniaxial tensile tests to evaluate the accuracy of the force-stress and displacement-strain relationships. Using this new specimen, dynamic experiments have been performed on aluminum 2024-T351 showing that strain rates in the range of 1000/s may be obtained without oscillations.