A phase field model for elastic-gradient-plastic solids undergoing hydrogen embrittlement
File(s)
Accepted version
Author(s)
Kristensen, Philip K
Niordson, Christian F
Martínez-Pañeda, Emilio
Type
Journal Article
Abstract
We present a gradient-based theoretical framework for predicting hydrogen assisted fracture in elastic-plastic solids. The novelty of the model lies in the combination of: (i) stress-assisted diffusion of solute species, (ii) strain gradient plasticity, and (iii) a hydrogen-sensitive phase field fracture formulation, inspired by first principles calculations. The theoretical model is numerically implemented using a mixed finite element formulation and several boundary value problems are addressed to gain physical insight and showcase model predictions. The results reveal the critical role of plastic strain gradients in rationalising decohesion-based arguments and capturing the transition to brittle fracture observed in hydrogen-rich environments. Large crack tip stresses are predicted, which in turn raise the hydrogen concentration and reduce the fracture energy. The computation of the steady state fracture toughness as a function of the cohesive strength shows that cleavage fracture can be predicted in otherwise ductile metals using sensible values for the material parameters and the hydrogen concentration. In addition, we compute crack growth resistance curves in a wide variety of scenarios and demonstrate that the model can appropriately capture the sensitivity to: the plastic length scales, the fracture length scale, the loading rate and the hydrogen concentration. Model predictions are also compared with fracture experiments on a modern ultra-high strength steel, AerMet100. A promising agreement is observed with experimental measurements of threshold stress intensity factor Kth over a wide range of applied potentials.
Date Issued
2020-10
Date Acceptance
2020-07-12
Citation
Journal of the Mechanics and Physics of Solids, 2020, 143, pp.1-23
ISSN
0022-5096
Publisher
Elsevier BV
Start Page
1
End Page
23
Journal / Book Title
Journal of the Mechanics and Physics of Solids
Volume
143
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
License URL
Identifier
https://www.sciencedirect.com/science/article/pii/S0022509620303276?via%3Dihub
Subjects
cond-mat.mtrl-sci
cond-mat.mtrl-sci
cs.CE
cs.NA
math.NA
physics.app-ph
Mechanical Engineering & Transports
01 Mathematical Sciences
02 Physical Sciences
09 Engineering
Publication Status
Published online
Article Number
104093
Date Publish Online
2020-07-13