Thermodynamic dislocation theory: Torsion of bars

Abstract

The thermodynamic dislocation theory developed for non-uniform plastic deformations is used here in an analysis of a bar subjected to torsion. Employing a small set of physics-based parameters, which we expect to be approximately independent of strain rate and temperature, we are able to simulate the torque-twist curve for a bar made of single crystal copper that agrees with the experimental one. arXiv:1806.04304v1 [cond-mat.soft]

Thermal softening during high-temperature torsional deformation of aluminum bars

“…Besides, the thermal effects are highly nontrivial. Examination of the experimental data provided in (Zhou and Clode, 1998) To counter these difficulties, we have resorted to the large-scale leastsquares analyses that we have developed in Le et al, 2018a;Le and Piao, 2018). That is, we have solved the system of ordinary differential equations (ODEs) numerically, provided a set of material parameters and initial values is known.…”

“…The aim of this paper is to explore use of the thermodynamic dislocation theory (Langer et al, 2010;Langer, 2015Langer, , 2016Le et al, , 2018bLe, 2018;Le et al, 2018a;Le and Piao, 2018) in modelling high-temperature torsional deformation of aluminum bars. We analyze a set of torsion tests for an aluminum alloy 5252 reported by Zhou and Clode (1998).…”

“…Our new ability to interpret data of the kind published in (Zhou and Clode, 1998) is due to the fact that the thermodynamic dislocation theory, in its latest versions (Langer, 2016;Le, 2018;Le et al, 2018a), includes the non-uniform plastic deformations and the thermal softening. Earlier versions of the theory (Langer et al, 2010;Langer, 2015) were developed exclusively for uniform plastic deformations.…”

“…Le and Piao (2018) have proposed a theory of twisted bars for both macro and micro sizes which shows that the density of excess dislocations is negligible for twisted bars of macro sizes with small to medium twist angles. For such bars a simple extension of the TDT is possible, which takes into account the spatial variation of state variables and ignores the excess dislocations, and was proposed by Le et al (2018a). To include the thermal effect, we extend that simple version of TDT in this paper by adding the equation for the ordinary kinetic vibrational temperature at which the temperature rise is caused by the movement of dislocations.…”

High‐temperature torsion of aluminum bars

“…Le [2] has extended this theory to non-uniform plastic deformation by accounting for excess dislocations (see also [3,4]). For bodies of macroscopic sizes the theory can essentially be simplified [5]. In this work we explore the use of this simplified version of TDT in modelling high-temperature torsional deformation of aluminum bars.…”