Localisation of deformation and damage under adiabatic compression

For dynamic compressive tests, the conditions of friction between the contact surfaces of the specimens and the bars are found to cause mechanical instability of materials with low strain hardening and low strain rate sensitivity. The adiabatic flow curves are described by a model using a weakening parameter taken into account both damage and thermally induced instability. In this paper, a material model is used, which is able to describe the material behaviour in the whole range of deformation, i.e. in the region of thermally activated processes with gradual transition to the region of damping-controlled processes.