Abstract
The research is devoted to studying the plasticity of metals and alloys in a cold state using the testing of the round specimens for tension. This paper aims to evaluate the accuracy of the Bridgman, Davidenkov-Spiridonova, and Ostsemin models used for calculation of stress triaxiality values on the basis of the neck geometry. The study was carried out using the computer simulation in the Deform-2D software. Specimens used for the simulation had a cylindrical gauge as well as a round notch with the initial ratio of minimum diameter to the radius of curvature in the range from 0.5 to 5. In addition, it was studied the influence of the hardening curve of material on the accuracy of the stress triaxiality determining. To evaluate the accuracy of the stress triaxiality values calculated on the basis of the neck geometry they were compared with the values determined by dividing mean stresses by equivalent ones. The research results showed the possibility to evaluate the stress triaxiality values in the center of the neck only for materials that do not have softening effects. The Ostsemin stress distribution model demonstrated the best accuracy.