The overturning of Riemann waves in elastoplastic media with hardening

Riemann waves (simple waves) are investigated within the von Mises elastoplasticity model with hardening. It is assumed that preceding processes have brought the medium into a state corresponding to a certain point on the loading surface. The conditions under which a Riemann wave overturns during its evolution, i.e., the conditions for the formation of discontinuities, are indicated.