Stage-II fatigue crack growth model from 3D dislocation dynamics simulations

ABSTRACT

Stage-II fatigue crack propagation in FCC metals is investigated using 3D discrete dislocation dynamics (DD) simulations. The calculations show that dislocation/grain–boundary interaction affects slip dispersion everywhere in the grain, including in the crack tip region. The results are analysed and drawn in the form of simple, quantitative mathematical expressions, depending on a set of physical variables. This approach helps in developing a comprehensive crack propagation model, where the crack growth rate da/dN depends on both the crack tip opening displacements and the tip-related nucleation of nano-cavities. It is shown that the modelled crack response is compatible with the well-known Paris expression, which we further interpreted as a ratio between the energy stored in the tip region over the energy spent extending the crack surfaces. The model validity is finally evaluated by a comparison with relevant experimental evidence.

KEYWORDS:

• Dislocation
• fatigue
• simulation
• crack
• crack growth

Acknowledgments

The views and opinions expressed herein do not necessarily reflect those of the European Commission. The complementary support of the Materials Research Program VALO of the Nuclear Energy Division; French Atomic Energy Commission (CEA/DEN) is acknowledged as well.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 EDDI under Grant Agreements No. 633053 and No. 755039. H2020 Euratom.