Problem on plastic flow at great deformations in the presence of ultrasonic vibrations

We consider the following two-stages process. At the first stage a body vib rates and by the dissipation of energy it is heated. At the second state a slowly varying in time mechanical load is superimposed on the vibrating bod y. This load creates great plastic deformations. The first stage is modeled by a coupled system of equations of forced vibration of a viscoelastic bod y and the heat equation. In the analysis of the second stage we apply the m odel of plastic flow under great deformations which was introduced and stud ied in [1].