To verify the mathematical model of the theory of processes, numerical calculations of the complex elastoplastic deformation of St3 steel along a flat curvilinear strain trajectory under combined tension-compression with torsion were carried out. The numerical calculations are compared with the experimental data obtained by the authors on the experimental complex SN-EVM on thin-walled tubular specimen. It is shown that the used mathematical model qualitatively and quantitatively satisfactorily describes the main effects of complex plastic deformation for the class of strain trajectories under consideration.