A1 Journal article (refereed), original research

Utilizing the theory of critical distances in conjunction with crystal plasticity for low-cycle notch fatigue analysis of S960 MC high-strength steel

Publication Details
Authors: Dabiri Mohammad, Lindroos Matti, Andersson Tom, Afkhami Shahriar, Laukkanen Anssi,
Björk Timo

Publisher: Elsevier
Publication year: 2018
Language: English
Related Journal or Series Information: International Journal of Fatigue
Volume number: 117
Start page: 257
End page: 273
Number of pages: 17
ISSN: 0142-1123
eISSN: 1879-3452
JUFO-Level of this publication: 2
Open Access: Not an Open Access publication


In the
current study, the elastoplastic reformulation of the theory of critical
distances (TCD) is used for low-cycle fatigue analysis of round specimens with
circumferential notches made of a direct-quenched high-strength steel. An
attempt is made to investigate the effect of microstructural heterogeneity
(which is absent in empirical notch analysis methods) on the estimation
capability of the TCD approach by embedding microstructural features in the numerical
analysis model. To this end, the originally proposed reformulation of TCD for the
low-cycle fatigue regime was modified by utilizing a numerical model equipped
with the constitutive equations of crystal plasticity for the critical zone of
the notch root. Necessary experimental tests and microstructural measurements were
performed to enable tuning of the parameters of the crystal plasticity
formulation and implementation of the numerical model. In order to keep the
complexity of the model at a reasonable level compared to its original form,
and to sustain its general applicability, some hypotheses and simplifications
were made in implementation of the numerical model, especially in presentation
of the grain morphology and post-processing of the results. The current
analysis highlights the effect of the material’s microstructural features on the
fatigue analysis approach under investigation and its main parameter, the material
characteristic length. It was seen that conservative estimations of low-cycle
fatigue life observed for sharper notches of the material when using
conventional TCD fatigue life analysis were slightly improved when material
characteristic length calculated with the crystal plasticity-embedded numerical
model was used.

Last updated on 2019-13-03 at 12:00