PhD opportunities

(SUBJECT PROVIDED) Modeling and simulation of damage in solid propellant under quasi-static loading based on micromechanical approach

Thesis proposal

Area of expertiseMécanique
Doctoral SchoolISMME - Ingénierie des Systèmes, Matériaux, Mécanique, Énergétique
SupervisorBESSON Jacques
Research unitCentre des Matériaux
KeywordsModeling, Simulation, cracking, damage
AbstractPropellants are energetic materials used in rocket and missile engines, and are composed of energetic fillers coated with an elastomer binder. Unlike the filled elastomers traditionally used in industry, these fillers are not intended to improve the mechanical strength of the material but to maximize its energetic performance. The life cycle of the engine from manufacture to commissioning can be long. The mechanical stresses undergone during the different phases (de-molding, storage, flight mission, launch) can lead to material damage and alter the nominal operation of the engine. The two most frequent damage mechanisms are the decohesion of the binder and the appearance, growth and coalescence of cavities in the binder. They generate additional combustion surfaces which increase the pressure of the combustion gases in the structure, potentially in an uncontrolled way. In this context, this thesis aims to better understand and model the mechanical behavior of these materials. For this purpose, a micromechanical model of the propellant will be developed to describe these degradation mechanisms at the charge scale. The fine description of the behavior of this composite material presents many challenges: taking into account the highly multiscale character induced by the polydisperse nature of the charges (from a few micrometers to several hundred micrometers) leads to large simulations (several tens of millions of unknowns). The hyper-elastic behavior of the binder invalidates the hypothesis of small perturbations. Damage to the binder and decohesion at the binder-filler interface lead to a smoothing behavior that requires regularization. To reduce the cost and complexity of finite element simulations, the proposed micromechanical models are often simplified (single mode loading, small deformation assumption, etc.). Recent progress in terms of high performance computing, available in the Z-set finite element suite, developed by the Mines ParisTech Materials Center and Onera, allows to lift these assumptions. A better understanding of the damage mechanisms and more predictive models will thus be obtained.

This thesis is part of the federative research project FLIBUSTIER which brings together chemists, fluid mechanics and solid mechanics on these topics.
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):

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
FundingContrat de recherche