Inter-sonic propagation of shear zone as an effect of longitudinal deformation

Abstract

Examples are presented when propagation of the boundaries of the zones of frictional sliding or elastic shear propagate with the speed of the longitudinal wave (or p-wave) and thus can be confused with the instances of intersonic fracture propagation. In these examples the mechanism of intersonic sliding/shear zone propagation is the longitudinal elastic deformation of the material surrounding the zone and hence controlled by the longitudinal wave velocity. Two simple models of intersonic sliding/shear zone propagation are considered: a frictional sliding of an elastic rod and shearing of an elastic rod on shear Winkler foundation. It is presumed that the shear Winkler layer can have either the conventional positive stiffness or apparent negative stiffness. In all these cases the sliding/shear zone propagates with the longitudinal wave velocity. In the case of negative stiffness of the Winkler layer the deformation rapidly increases with time reflecting the presence of influx of the external energy required by the system that realises negative stiffness.