Shear Localisation During Deformation of Thermo-Visco-Plastic Materials

The mechanisms responsible for ignition of explosive materials in response to low energy stimuli, known as “insults" in the literature, are still not well understood. It is in general believed that explosive ignition is of thermal origin, with mechanical energy being converted into heat energy in localised regions, forming so-called “hot spots”.

We investigate how an instability caused by thermal softening may give rise to localised plastic deformation which may lead to subsequent ignition. We consider the homogenous deformation of a material which exhibits strain hardening, strain-rate hardening and thermal softening behaviour. As the strain is increased the material enters into the plastic regime and hardening behaviour is observed, exacerbated by any material inhomogeneity.