PLASTIC SHEARING AT HIGH AND VERY HIGH-STRAIN RATES

Shear straining at different velocities, including high and very high strain rates, is discussed. Some experimental techniques which allows for experiments at high and very high strain rates are briefly reviewed. A new experimental technique based on direct impact on Modified Double Shear a specimen (MDS) is also reviewed. A one-dimensional model for simple shear is applied together with a constitutive relation which takes into account rate and temperature sensitivity a generalised condition for instability of adiabatic shearing at different rates has been derived and discussed. Finally, an analysis of deformation trapping in shear due to thermoplastic instability in one-dimensional plastic wave propagation is analysed. The critical impact velocity in shear is analysed in detail and values are compared with preliminary experiments.