The strain rate concentration factor for round and flat test specimens

In this study, the strain rate concentration is considered for high speed tensile test, which is now being recognized as a standard testing method. To evaluate the impact strength of engineering materials, Izod and Charpy tests are unsuitable since they cannot control the impact speeds and therefore the testing results do not coincide with the real failure of real products. For smooth specimens, the strain rate can be determined from the tensile speed u/t and specimen length l as ε̇_smooth=u/tl. For notched specimens, however, the strain rate at the notch root ε̇_notch should be analyzed accurately. In this study, therefore, the strain rate concentration factor defined as K_{t ε̇} = ε̇_notch/ε̇_smooth is studied with varying the notch geometry and specimen length for round and flat test specimens. In particular, the relationship between the strain rate concentration factor and the stress concentration factor is investigated by varying the notch geometry and specimen length.