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

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 pres...

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Main Authors: Juul, KJ, Martínez-Pañeda, E, Nielsen, KL, Niordson, CF
Format: Journal article
Sprog:English
Udgivet: Elsevier 2019
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author Juul, KJ
Martínez-Pañeda, E
Nielsen, KL
Niordson, CF
author_facet Juul, KJ
Martínez-Pañeda, E
Nielsen, KL
Niordson, CF
author_sort Juul, KJ
collection OXFORD
description 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.
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spelling oxford-uuid:47be3669-fc51-46b3-86a2-b567129876cf2024-02-29T06:42:37ZSteady-state fracture toughness of elastic-plastic solids: isotropic versus kinematic hardeningJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:47be3669-fc51-46b3-86a2-b567129876cfEnglishSymplectic ElementsElsevier2019Juul, KJMartínez-Pañeda, ENielsen, KLNiordson, CFThe 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.
spellingShingle Juul, KJ
Martínez-Pañeda, E
Nielsen, KL
Niordson, CF
Steady-state fracture toughness of elastic-plastic solids: isotropic versus kinematic hardening
title Steady-state fracture toughness of elastic-plastic solids: isotropic versus kinematic hardening
title_full Steady-state fracture toughness of elastic-plastic solids: isotropic versus kinematic hardening
title_fullStr Steady-state fracture toughness of elastic-plastic solids: isotropic versus kinematic hardening
title_full_unstemmed Steady-state fracture toughness of elastic-plastic solids: isotropic versus kinematic hardening
title_short Steady-state fracture toughness of elastic-plastic solids: isotropic versus kinematic hardening
title_sort steady state fracture toughness of elastic plastic solids isotropic versus kinematic hardening
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AT martinezpanedae steadystatefracturetoughnessofelasticplasticsolidsisotropicversuskinematichardening
AT nielsenkl steadystatefracturetoughnessofelasticplasticsolidsisotropicversuskinematichardening
AT niordsoncf steadystatefracturetoughnessofelasticplasticsolidsisotropicversuskinematichardening