Modeling the Behavior of Elastoplastic Rods During Tension–Torsion Deformation and Plotting Their Strain Diagram Before Rupture While Taking into Account the Type of Stress–Strain State

In the scientific literature, there is no clear conclusion on the reliability of the “single-curve hypothesis” at large strains because of the complexity of the experimental analysis of the inhomogeneous stress–strain state (SSS). The authors have developed an experimental calculation method, the integral characteristics (generalized forces and displacements) of the deformation process in which are determined experimentally and the changes in the inhomogeneous SSS of which are determined numerically. This method makes it possible to establish an essential dependence of the strain diagrams in tension and torsion on the type of stress state for steels 09G2S, 10KhSND, and 10G2FBYu under moderate and large deformations and to refine significantly the results of numerical modeling of the processes of elastoplastic deformation of rods under combined tensile–torsion loading. The proposed fast-converging algorithm is applicable for plotting strain diagrams under other types of quasistatic and dynamic loading: compression, penetration, bending, etc.