CURRENT INSTABILITY OF HARDENING OF DEFORMABLE MEDIUM MICROELEMENT AS A REASON OF NECK PROPAGATION

10.25712/ASTU.1811-1416.2022.04.004

Abstract

The influence of “current” instability of the deformable medium element hardening to the localization of deformation at different scale levels was studied. The term the "current instability" was used as an analogy with the current instabilities of the semiconductors electrical conductivity in strong electric fields with the specific current-voltage curves (I-U) [1]. The similar shapes of the hardening curves of an element of a deformable medium   (σ-ε) were considered as the cause of deformation localization. The phenomena of deformation localization caused by "current" instabilities of various types were considered and modeled. It was shown that the scenario of plastic flow in the case of "current" instability at the level of a microelement of the medium can manifest itself at the macro scale level of plastic flow in the form of various types of localizations. The simulation was carried out on the basis of a two-level finite element model proposed earlier by the authors [2]. The cases when either a “stable” neck or neck propagation at the macrolevel during uniaxial tension of the sample were observed. Ones depended on the shape of the hardening curves of the elementary volume of the deformed sample similar the current instability curves.