Separation of waves propagating in an elastic or viscoelastic Hopkinson pressure bar with three-dimensional effects

The Split Hopkinson pressure bar technique needs the separation of the waves propagating in opposite directions. The wave separation can be performed whatever the test duration by using the two-point strain measurement method based on the elastic one-dimensional wave propagation theory. If the three-dimensional effects due to the radial inertia are important or if the bar is viscoelastic, wave dispersion and attenuation occur and the previous method cannot be used accurately. This paper presents a new two-point strain measurement method which takes account of the wave dispersion and attenuation. The wave separation is performed in the frequency and time domains. The method is validated with numerical simulations on an elastic bar and experimentally with a viscoelastic PMMA bar.