Steady-state fracture toughness of elastic-plastic solids: Isotropic versus kinematic hardening

K. J. Juul*, E. Martínez Pañeda, K.L. Nielsen, C. F. Niordson

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The fracture toughness for a mode I/II crack propagating in a ductile material has been subject to numerous investigations. However, the influence of the material hardening law has received very limited attention, with isotropic hardening being the default choice if cyclic loads are absent. The present work extends the existing studies of monotonic mode I/II steady-state crack propagation with the goal to compare the predictions from an isotropic hardening model with that of a kinematic hardening model. The work is conducted through a purpose-built steady-state framework that directly delivers the steady-state solution. In order to provide a fracture criterion, a cohesive zone model is adopted and embedded at the crack tip in the steady-state framework, while a control algorithm for the far-field, that significantly reduces the number of equilibrium iterations is employed to couple the far-field loading to the correct crack tip opening. Results show that the steady-state fracture toughness (shielding ratio) obtained for a kinematic hardening material is larger than for the corresponding isotropic hardening case. The difference between the isotropic and kinematic model is tied to the non-proportional loading conditions and reverse plasticity. This also explains the vanishing difference in the shielding ratio when considering mode II crack propagation as the non-proportional loading is less pronounced and the reverse plasticity is absent.
Original languageEnglish
JournalEngineering Fracture Mechanics
Volume207
Pages (from-to)254-268
ISSN0013-7944
DOIs
Publication statusPublished - 2019

Keywords

  • Steady-state
  • Isotropic hardening
  • Kinematic hardening
  • Active plastic zone
  • Shielding ratio

Cite this

@article{d9f32b89a828410faddeb27021a83b4d,
title = "Steady-state fracture toughness of elastic-plastic solids: Isotropic versus kinematic hardening",
abstract = "The fracture toughness for a mode I/II crack propagating in a ductile material has been subject to numerous investigations. However, the influence of the material hardening law has received very limited attention, with isotropic hardening being the default choice if cyclic loads are absent. The present work extends the existing studies of monotonic mode I/II steady-state crack propagation with the goal to compare the predictions from an isotropic hardening model with that of a kinematic hardening model. The work is conducted through a purpose-built steady-state framework that directly delivers the steady-state solution. In order to provide a fracture criterion, a cohesive zone model is adopted and embedded at the crack tip in the steady-state framework, while a control algorithm for the far-field, that significantly reduces the number of equilibrium iterations is employed to couple the far-field loading to the correct crack tip opening. Results show that the steady-state fracture toughness (shielding ratio) obtained for a kinematic hardening material is larger than for the corresponding isotropic hardening case. The difference between the isotropic and kinematic model is tied to the non-proportional loading conditions and reverse plasticity. This also explains the vanishing difference in the shielding ratio when considering mode II crack propagation as the non-proportional loading is less pronounced and the reverse plasticity is absent.",
keywords = "Steady-state, Isotropic hardening, Kinematic hardening, Active plastic zone, Shielding ratio",
author = "Juul, {K. J.} and {Mart{\'i}nez Pa{\~n}eda}, E. and K.L. Nielsen and Niordson, {C. F.}",
year = "2019",
doi = "10.1016/j.engfracmech.2018.12.016",
language = "English",
volume = "207",
pages = "254--268",
journal = "Engineering Fracture Mechanics",
issn = "0013-7944",
publisher = "Pergamon Press",

}

Steady-state fracture toughness of elastic-plastic solids: Isotropic versus kinematic hardening. / Juul, K. J.; Martínez Pañeda, E.; Nielsen, K.L.; Niordson, C. F.

In: Engineering Fracture Mechanics, Vol. 207, 2019, p. 254-268.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Steady-state fracture toughness of elastic-plastic solids: Isotropic versus kinematic hardening

AU - Juul, K. J.

AU - Martínez Pañeda, E.

AU - Nielsen, K.L.

AU - Niordson, C. F.

PY - 2019

Y1 - 2019

N2 - The fracture toughness for a mode I/II crack propagating in a ductile material has been subject to numerous investigations. However, the influence of the material hardening law has received very limited attention, with isotropic hardening being the default choice if cyclic loads are absent. The present work extends the existing studies of monotonic mode I/II steady-state crack propagation with the goal to compare the predictions from an isotropic hardening model with that of a kinematic hardening model. The work is conducted through a purpose-built steady-state framework that directly delivers the steady-state solution. In order to provide a fracture criterion, a cohesive zone model is adopted and embedded at the crack tip in the steady-state framework, while a control algorithm for the far-field, that significantly reduces the number of equilibrium iterations is employed to couple the far-field loading to the correct crack tip opening. Results show that the steady-state fracture toughness (shielding ratio) obtained for a kinematic hardening material is larger than for the corresponding isotropic hardening case. The difference between the isotropic and kinematic model is tied to the non-proportional loading conditions and reverse plasticity. This also explains the vanishing difference in the shielding ratio when considering mode II crack propagation as the non-proportional loading is less pronounced and the reverse plasticity is absent.

AB - The fracture toughness for a mode I/II crack propagating in a ductile material has been subject to numerous investigations. However, the influence of the material hardening law has received very limited attention, with isotropic hardening being the default choice if cyclic loads are absent. The present work extends the existing studies of monotonic mode I/II steady-state crack propagation with the goal to compare the predictions from an isotropic hardening model with that of a kinematic hardening model. The work is conducted through a purpose-built steady-state framework that directly delivers the steady-state solution. In order to provide a fracture criterion, a cohesive zone model is adopted and embedded at the crack tip in the steady-state framework, while a control algorithm for the far-field, that significantly reduces the number of equilibrium iterations is employed to couple the far-field loading to the correct crack tip opening. Results show that the steady-state fracture toughness (shielding ratio) obtained for a kinematic hardening material is larger than for the corresponding isotropic hardening case. The difference between the isotropic and kinematic model is tied to the non-proportional loading conditions and reverse plasticity. This also explains the vanishing difference in the shielding ratio when considering mode II crack propagation as the non-proportional loading is less pronounced and the reverse plasticity is absent.

KW - Steady-state

KW - Isotropic hardening

KW - Kinematic hardening

KW - Active plastic zone

KW - Shielding ratio

U2 - 10.1016/j.engfracmech.2018.12.016

DO - 10.1016/j.engfracmech.2018.12.016

M3 - Journal article

VL - 207

SP - 254

EP - 268

JO - Engineering Fracture Mechanics

JF - Engineering Fracture Mechanics

SN - 0013-7944

ER -