Next Article in Journal
Consolidation Modeling during Thermoforming of Thermoplastic Composite Prepregs
Next Article in Special Issue
Studying Grain Boundary Strengthening by Dislocation-Based Strain Gradient Crystal Plasticity Coupled with a Multi-Phase-Field Model
Previous Article in Journal
Defects, Diffusion, and Dopants in Li2Ti6O13: Atomistic Simulation Study
Open AccessArticle

Micromechanical Modelling of the Influence of Strain Ratio on Fatigue Crack Initiation in a Martensitic Steel-A Comparison of Different Fatigue Indicator Parameters

1
Robert Bosch GmbH—Corporate Sector Research and Advance Engineering, 71272 Renningen, Germany
2
Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universität Bochum, 44801 Bochum, Germany
*
Author to whom correspondence should be addressed.
Materials 2019, 12(18), 2852; https://doi.org/10.3390/ma12182852
Received: 1 August 2019 / Revised: 26 August 2019 / Accepted: 31 August 2019 / Published: 4 September 2019
(This article belongs to the Special Issue Micromechanics: Experiment, Modeling and Theory)
Micromechanical fatigue lifetime predictions, in particular for the high cycle fatigue regime, require an appropriate modelling of mean stress effects in order to account for lifetime reducing positive mean stresses. Focus of this micromechanical study is the comparison of three selected fatigue indicator parameters (FIPs), with respect to their applicability to different total strain ratios. In this work, investigations are performed on the modelling and prediction of the fatigue crack initiation life of the martensitic high-strength steel SAE 4150 for two different total strain ratios. First, multiple martensitic statistical volume elements (SVEs) are generated by multiscale Voronoi tessellations. Micromechanical fatigue simulations are then performed on these SVEs by means of a crystal plasticity model to obtain microstructure dependent fatigue responses. In order to account for the material specific fatigue damage zone, a non-local homogenisation scheme for the FIPs is introduced for lath martensitic microstructures. The numerical results of the different non-local FIPs are compared with experimental fatigue crack initiation results for two different total strain ratios. It is concluded that the multiaxial fatigue criteria proposed by Fatemi-Socie is superior for predicting fatigue crack initiation life to the energy dissipation criteria and the accumulated plastic slip criteria for the investigated total strain ratios. View Full-Text
Keywords: martensitic steel; fatigue crack initiation; crystal plasticity; fatigue indicator parameters martensitic steel; fatigue crack initiation; crystal plasticity; fatigue indicator parameters
Show Figures

Figure 1

MDPI and ACS Style

Schäfer, B.J.; Sonnweber-Ribic, P.; ul Hassan, H.; Hartmaier, A. Micromechanical Modelling of the Influence of Strain Ratio on Fatigue Crack Initiation in a Martensitic Steel-A Comparison of Different Fatigue Indicator Parameters. Materials 2019, 12, 2852.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop