Syvak R. The development of scientific foundations of the mechanics of non-monotonic plastic deformation and the improvement of technological processes of metal forming

The thesis is aimed at solving an important scientific and technical problem of increasing the efficiency of metal forming processes based on the development of the scientific foundations of the mechanics of non-monotonic plastic deformation. On the basis of the Backhaus-Del body's anisotropically hardening body model, a calculating device has been developed, which makes it possible to obtain a reliable estimate of the stress-strain state under non-monotonic plastic deformation. Physical equations are proposed for calculating the components of the stress deviator for non-monotonic plastic deformation, taking into account the influence of the curvature of the deformation trajectories. A tensor model of the damage accumulation process with non-monotonic deformation is developed. Theoretical and experimental studies of the influence of the fracture angle of the loading trajectory and the value of the used plasticity resource before the fracture on the dependence of the value of the used resource on the angle of the fracture. With the help of the proposed computational apparatus, studies of technological processes of metal forming were performed, a characteristic feature of which is non-monotonic plastic deformation. The influence of the parameters of the process of radial extrusion with further sedimentation of cylindrical billets on the value of the used plasticity resource was evaluated. An estimate was made of the value of the plasticity resource used in the implementation of plastic deformation of the metal of the surface layer with multiple unloadings. Selected rational modes and parameters for the implementation of the rotary hood. Studies of the influence of the parameters of the rotational drawing process on the plasticity and stability of the process of forming sheet blanks in the manufacture of axisymmetric parts were carried out and rational modes were selected for implementing the rotational drawing on CNC machines.