University of Oulu

Lindroos, M., Laukkanen, A., Andersson, T., Vaara, J., Mäntylä, A., & Frondelius, T. (2019). Micromechanical modeling of short crack nucleation and growth in high cycle fatigue of martensitic microstructures. Computational Materials Science, 170, 109185.

Micromechanical modeling of short crack nucleation and growth in high cycle fatigue of martensitic microstructures

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Author: Lindroos, Matti1; Laukkanen, Anssi1; Andersson, Tom1;
Organizations: 1VTT Lifecycle Solutions, Espoo, Finland
2R&D and Engineering, Wärtsilä, P.O.Box 244, 65101 Vaasa, Finland
3Materials and Mechanical Engineering, University of Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 4.6 MB)
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Language: English
Published: Elsevier, 2019
Publish Date: 2022-03-31


High cycle fatigue (HCF) is a frequently limiting failure mechanism of machine elements and modern high strength steels. Present day design rules rely on semi-empirical methods, guidelines and utilization of macroscopic analysis means in origin, such as fracture mechanics. The resulting challenge is that short crack regime, critical for HCF in terms of lifetime of components and products, is somewhat poorly handled. This is an outcome of the fact that the present means and methodologies do not explicitly account for effects arising from material microstructure, an oversight micromechanics aims to rectify.

Micromechanical modeling operating on fatigue at the scale of material microstructure necessitates the introduction of suitable means to describe the mechanisms of cyclic plastic deformation and microstructural morphologies, considered critical for HCF especially at the early stages of micro-crack nucleation and damage evolution towards and within the short crack regime. In current work, a crystal plasticity based approach with combined hardening is utilized to capture the respective deformation response utilizing full field modeling. The modeling is carried out for both simplified prior austenite grain like microstructures as well as complex imaging based martensitic quenched and tempered steel microstructural models. A fully coupled damage modeling scheme is introduced to track damage nucleation and evolution at the scale of the studied microstructures. Crack closure is included within the approach to track behavior of microstructure scale defects under, e.g., fully reversed loading, more realistically. Model calibration is addressed and application cases involving damage and crack growth both under monotonic and cyclic loading are presented.

The results demonstrate how the coupling of damage to crystal plasticity modeling can be utilized to identify and track the evolution of microstructure scale damage mechanisms in complex martensitic microstructures. Interactions between strain localization and damage accumulation are presented as well as transition from micro-cracking to short crack growth. The results show that the proposed approach can interpret the intricate dependencies and relations between complex microstructures, their (cyclic) deformation mechanisms and evolution of damage, the outcomes regarding crack formation and behavior are found to be in line with similar experimental studies.

The proposed framework for modeling damage in polycrystalline microstructures is quite general in its capabilities. By solely introducing a suitable crystal plasticity based deformation model and a damage model describing nucleation and softening can plastic slip and damage interactions be studied in complex microstructures, and in principle, on any system where similar constitutive models are utilizable. The exploitation of the resulting micromechanical modeling and simulation capabilities lies both in simulation driven design of fatigue resistant components and high strength steels.

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Series: Computational materials science
ISSN: 0927-0256
ISSN-E: 1879-0801
ISSN-L: 0927-0256
Volume: 170
Article number: 109185
DOI: 10.1016/j.commatsci.2019.109185
Type of Publication: A1 Journal article – refereed
Field of Science: 214 Mechanical engineering
216 Materials engineering
Funding: Finally, the authors would like to acknowledge the financial support of Business Finland (former Tekes) in the form of a research project WIMMA Dnro 1566/31/2015.
Copyright information: © 2019 Elsevier B.V. This manuscript version is made available under the CC-BY-NC-ND 4.0 license