Conditions for the localisation of plastic deformation in temperature sensitive viscoplastic materials

TitleConditions for the localisation of plastic deformation in temperature sensitive viscoplastic materials
Publication TypeJournal Article
Year of Publication2016
AuthorsMK Paesold, AP Bassom, K Regenauer-Lieb, and M Veveakis
JournalJournal of Mechanics of Materials and Structures
Volume11
Start Page113
Issue2
Pagination113 - 136
Date Published01/2016
Abstract

We study the onset of localisation of plastic deformation for a class of materials that exhibit both temperature and rate sensitivity. The onset of localisation is determined via an energy bifurcation criterion, defined by the postulate that viscoplastic materials admit a critical (mechanical) energy input above which deformation becomes unstable and plastic localisation ensues. In analogy to the classical concepts of mechanics, the conditions for the onset of localisation in temperature-sensitive viscoplastic materials are reached at a critical stress. However, it is shown that in viscoplastic materials a material bifurcation occurs when the heat supply through mechanical work surpasses the diffusion capabilities of the material. This transition from near-isothermal stable evolution to near-adiabatic thermal runaway is the wellknown concept of shear heating. Here, it is generalised and the correspondence between this runaway instability and the localisation of plastic deformation in solid mechanics is detailed. The obtained phase space controlling the localisation is shown to govern the evolution of the system in the postyield regime. These results suggest that the energy balance essentially drives the evolution of the plastic deformation and therefore constitutes a physics-based hardening law for thermoviscoplastic materials.

DOI10.2140/jomms.2016.11.113
Short TitleJournal of Mechanics of Materials and Structures