Abstract
Intermediate and high strain rate experiments are of a limited duration. Thus, the specimen temperature cannot be assumed constant. In this work, we investigated the adiabatic assumption in intermediate and high strain experiments. A two-step one-dimensional model was developed to simulate the temperature rise in Hopkinson bar experiments for strain rates ranging between 1 and 5000/s. The model is applied to predict temperature rise in an aluminum alloy. The adiabatic assumption is shown to be valid for strain rates higher than 500/s. However, the isothermal assumption is not valid even at 1/s of strain rate. These conclusions are very important for the interpretation of the stress-strain curves that are measured at medium and high strain rates.