PhD opportunities

Modeling of tantalum sheet forming and prediction, by polycrystalline approaches, of the material generated on parts: mechanical behavior and microstructure

Thesis proposal

Area of expertiseMécanique
Doctoral SchoolISMME - Ingénierie des Systèmes, Matériaux, Mécanique, Énergétique
SupervisorFOREST Samuel
Research unitCentre des Matériaux
KeywordsCrystal plasticity, tantalum, sheet forming, polycrystal, thermal treatments, finite elements
AbstractPredicting the microstructure and mechanical properties of industrial components after the manufacturing process, including forming and heat treatment, is a key issue in modern mechanics of materials. Polycrystalline models (homogenized or full field), capable of providing a map, even partial, of mechanical properties (internal stresses and subsequent mechanical response) and metallurgical properties (crystallographic texture, dislocation densities, grain sizes), are insufficiently used today in an industrial context. The objective of the thesis is to show the potential of polycrystalline models in the case of hydroforming of tantalum, a particularly ductile metal. Parallel massive calculations will be implemented for a homogenized polycrystalline elastoviscoplastic model based on dislocation density, starting from the knowledge of the crystallographic texture. The local states obtained in the part will then be used to predict the metallurgical evolution of the microstructure following a heat treatment after forming. For this purpose, a recent original model coupling mechanics and phase field method in full field simulations (polycrystalline aggregates) will be used to predict the migration of grain boundaries and the nucleation of new grains from the intragranular heterogeneous field of crystal orientation and dislocation densities. The numerical predictions will be compared at each step to available experimental results as well as new mechanical tests and microstructural observations, custom made during the thesis.
ProfileEngineer and / or Master of Science - Good level of general and scientific culture. Good level of knowledge of French (B2 level in french is required) and English. (B2 level in english is required) Good analytical, synthesis, innovation and communication skills. Qualities of adaptability and creativity. Teaching skills. Motivation for research activity. Coherent professional project.

Prerequisite (specific skills for this thesis):

Thermomechanics of materials, computational mechanics, viscoplasticity, constitutive laws.

Applicants should supply the following :
• a detailed resume
• a copy of the identity card or passport
• a covering letter explaining the applicant’s motivation for the position
• detailed exam results
• two references : the name and contact details of at least two people who could be contacted
• to provide an appreciation of the candidate
• Your notes of M1, M2
• level of English equivalent TOEIC

to be sent to recrutement_these@mat.mines-paristech.fr
FundingContrat de recherche