Postdoctoral position in numerical modeling of fatigue crack propagation (M/F)

Reliable fatigue crack propagation models are essential in all industries where fatigue cracks are a major concern for safety reasons, such as in the energy and transportation sectors. Fatigue life predictions for these components are often based on crack propagation calculations, with initiation accounting for a negligible portion of the life. However, structural components, e.g. in aeronautical, railway or automotive applications, are inevitably subjected to fatigue under varying load magnitudes. Even when components are designed for constant amplitude loading, the occurrence of overloads or underloads in service is frequent and affects the rate of fatigue crack propagation. In most metal alloys, a few cycles of crack acceleration followed by deceleration are observed after an overload.

The goal of the ANR ADVENTURE project (dAta DriVEn iNvestigation of faTigUe cRack growth with ovErload effects) is to better understand the effects of overloading on established cracks but also on small 3d cracks during the transitions between initiation and propagation.

In the framework of the ANR-ADVENTURE project, a 1 year post-doc contract is open at GeM. The candidate will focus on simplified numerical modeling of fatigue propagation, but taking into account the effects of overload. In the envisaged strategy, higher order terms of the asymptotic development of the elastic solution at the crack tip will be accounted for in order to estimate the size of the plastic zone at the crack tip. This size of the plastic zone will then be used to correct the propagation speed thanks to a model in the spirit of Wheeler's model [1], [2]. The model will be based on rich experimental data obtained from full 3D displacement fields measurements using X-ray tomographies acquired during in-situ experiments.

[1] Wheeler OE. Spectrum loading and crack growth. J Basic Eng, Trans ASME 1972;94(1):181–6.
[2]B.K.C. Yuen, F. Taheri. Proposed modifications to the Wheeler retardation model for multiple overloading fatigue life prediction I.J.F 28 (2006) 1803–1819

The post-doctoral fellow shall contribute to :
- experimental data analysis
- data-driven stress reconstruction
- plastic activity crack growth relationship
- definition of modeling features
- implementation and validation

The open position is part of the ANR ADVENTURE project in which 4 partners are involved. Three academic research labs are in the project: LaMCube (UMR9013), MATEIS (UMR5510) and GeM (UMR6183). The CETIF is also involved as an industrial partner.