El centro de investigaciones en física de los materiales en Rouen, Francia, dispone de una beca de tres años para desarrollar una tesis en mecánica de los materiales.
El contrato empieza el 03 de Octubre del 2016.
Buscamos a un candidato con muy buenos conocimientos en el comportamiento mecánico de los materiales metálicos asi como una primera experiencia en microscopia electrónica.
Contacto: Clement Keller, assistant professor, clement.keller en insa-rouen.fr, +33232959865.
Pagina web del centro: http://gpm.labos.univ-rouen.fr/?lang=fr/
Descripción del proyecto:
The use of shaping processes in the production of mechanical parts can lead to early failure during their future thermomechanical sollicitation in service. For metallic materials cyclically strain loaded, the initial strain experienced by the material during its forming process induces a modification in the cyclical behavior (increased stress level and decrease in the number of cycles to failure) compared to the same material not previously work-hardened. This effect of the initial plastic strain depends on the deformation mechanisms of the material, the amplitude and type of the prestrain (monotonic or cyclic) and the amplitude of fatigue loading1,2.
For cyclic stress loads, it seems that the initial plastic strain also plays an important role on the cyclic behavior. The existence of an initial microstructure generates, if the latter is not restored by a stage of creep, the accumulation of inelastic strain, a phenomenon generally called ratchet 3. In the case of 316L, a 2 h creep stage at room temperature eliminates part of this cyclical accumulation of inelastic strain, which seems to question the community's knowledge of the ratchet phenomenon.
The objective of this PhD thesis is to continue the work started about the link between the initial microstructure and the cyclic accumulation of inelastic strain in the Ermeca team of the Material Physics Group. To this aim, a study of the origin of the ratchet phenomenon will be performed for three cubic face-centered materials with different stacking fault energies and different microstructures. These three materials will be then subjected to cyclic stress controlled loadings with different stress amplitude and mean stress. By combining the results of these mechanical tests to a microstructural analysis, the purpose is to understand the origin of the cyclic accumulation of inelastic strain and to determinate its characteristics according to the studied material.
All the experiments will be carry out using the platform of mechanical tests and microstructural analysis (SEM/EBSD/TEM) of the laboratory. The candidate should have strong knowledge of the mechanical behavior of metallic materials and a taste for the experimental. A first experience on the realization of cyclic testing or SEM/TEM analyses will be appreciated. The candidate will demonstrate independence and rigor and a good level of English is requiered for written and oral communications.
The work will be supervised by Clément Keller (assistant professor, clement.keller en insa-rouen.fr) et Lakhdar Taleb (Professor, lakhdar.taleb en insa-rouen.fr).
Gross salary : around 1600 €
1 G. Marnier, C. Keller, L. Taleb, International Journal of Plasticity, 78 (2016) 64-83
2 A. Belattar, C. Keller, L. Taleb, Material Science and Engineering, A662 (2016) 468-480
3 L. Taleb, International Journal of Plasticity, 43 (2013) 1-19