A nonequilibrium thermodynamic model for viscoplasticity coupled with damage for BCC metals

We present a physically enhanced ductile damage model applicable for body centered cubic (BCC) metals. The current proposition extends the authors' recent work on thermo-viscoplasticity based on two-temperature thermodynamics and physics of disparate types of dislocation densities. The descript...

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Bibliographic Details
Published in:Mechanics of advanced materials and structures 2020-07, Vol.27 (13), p.1110-1119
Main Authors: Kar, Gurudas, Roy Chowdhury, Shubhankar, Roy, Debasish
Format: Article
Language:English
Subjects:
BCC metals
Boundary value problems
Continuum damage mechanics
Damage assessment
Dislocation density
Dislocation mobility
ductile damage
Ductile fracture
kinetic-vibrational and configurational subsystems
Microcracks
mobile and forest dislocations
Nonequilibrium thermodynamics
Thermodynamic models
Two-temperature thermodynamics
Viscoplasticity
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Summary:We present a physically enhanced ductile damage model applicable for body centered cubic (BCC) metals. The current proposition extends the authors' recent work on thermo-viscoplasticity based on two-temperature thermodynamics and physics of disparate types of dislocation densities. The description of the thermodynamic system involves primarily two types of variables (or degrees of freedom, DOFs) representing several micro/meso-scopic processes occurring in two separable time-scales during ductile damage. Processes of rearrangement and movement of defects, namely dislocations, voids, micro-cracks, take place in a time scale much slower than that of the vibration of atoms about their equilibrium positions in the lattice. Consequently, they appear in the thermodynamic theory in terms of slow configurational DOFs and the fast kinetic vibrational DOFs respectively. While we consider physics based internal variables, e.g., mobile and forest dislocation densities, for modeling viscoplasticity alone, material degradation due to ductile damage is treated in a phenomenological fashion taking recourse to the framework of continuum damage mechanics. In order to assess the performance of our proposal, numerical experiments on boundary value problems of viscoplasticity with or without damage are carried out and validated against available experimental evidence.
ISSN:1537-6494
1537-6532
DOI:10.1080/15376494.2020.1717692