Physics, Mechanics and Plasticity group

Polymer materials microstructure / physical properties relationship (coordinators: Isabelle Royaud, Marc Ponçot)

The scientific developments of the goup are focused on understanding the impact of long-term aging processes on mechanical behavior.
This approach involves monitoring the evolution of the microstructure under mechanical stress, knowing that aging (physical or chemical) may be due to:

• degradation with oxidation
• scission and / or crosslinking of macromolecule chains
• thermal degradation of the material at high strain rates
• a structural evolution (crystallinity, orientation, physical aging in the amorphous phase, volume damage)
• interfacial damage in composites, degradation phenomena specific to aggressive environments (for example, biomaterials for a bioartificial pancreas resistant to aging in vivo)

The overall objective is to predict long-term mechanical behavior, based on an understanding of the plasticity and damage of different types of materials. This approach must lead to the prediction of long-term service life, in particular in the context of the development of sustainable and eco-compatible materials.

Projects:

• FUI MECABARP
• Welding Institute (IS)
• Renault

Theses:

• Arkema / CEA / INES, Stéphane OGIER (2014-2017)
• FUI Mecabarp, Martin DONNAY (2014- 2017)
• Solenne COLLOMB (2017-2020)

Article:

In situ study of the deformation micro-mechanisms of semicrystalline polyethylene terephthalate films using synchrotron radiation X-ray scattering, Polymer, 117, 268-281, 2017, Martin Donnay; Marc Ponçot; Jean-Philippe Tinnes; Thomas Schenk; Olivier Ferry; Isabelle Royaud,

Monitoring and identification of elementary mechanisms of deformation and damage to materials (coordinators: Thomas Schenk, Isabelle Royaud, Marc Ponçot)

The scientific activity of the group is based on the understanding and modeling of the mechanical behavior of innovative materials from elementary micro-mechanisms of deformation:

• displacement of dislocations and defects in the case of metallic materials
• molecular mobility of macromolecules
• volume or composite damage (at the level of the fibers, the matrix or the fiber / matrix interface).

The materials studied are very varied: metallic materials, polymers, biomaterials (up to living material) and composites.

Projects:

• LabEx DAMAS
• MIB project
• CNES

Theses:

• MESR, Khaoula BEN HAFSIA (2013-2016)
• LabEx DAMAS, Komlavi SENYO ELOH (2017-2020)

Article:

Study of the Poly (Ethylene Terephthalate) crystallization by coupling Raman Spectroscopy and Differential Scanning Calorimetry, Journal of Polymer Research, 23 (5), 1-14, 2016, K. Ben Hafsia, M. Ponçot, P. Bourson, D. Chapron, I. Royaud

Mechanics of damage to composites (coordinator: Zoubir Ayadi)

The overall scientific objective is to assess the effect of damage to composites on the elastic properties of the structure. Good progress has been made so far in the case of static loads. This research work mainly focuses on understanding fatigue damage. The two main themes are:

• Microcracks and delaminations of laminated composites subjected to quasi-static and cyclic loading.
   
• Study of the effect of the microstructure on the initiation and the spread of detachment at the fiber-matrix interface by Representative Elementary Volume (VER) models for unidirectional composites and cross laminates.

This objective is developed in the framework of a strong partnership with the Technical University of Lulea in Sweden.
Three approaches are used: Theoretical (global-Local model), Experimental (full field method) and numerical (finite elements). They are divided into two sub-themes:

• Introduction of Micro Damage and growth in laminates under quasi-static tensile loading and fatigue
   
• Fatigue damage to thin composites for aeronautical applications.

Theses:

• Hiba BEN KHALA
• Luca DI STASIO 

Articles:

Energy release rate of the fiber / matrix interface crack in UD composites under transverse loading: effect of the fiber volume fraction and of the distance to the free surface and to non-adjacent debonds, Theoretical and Applied Fracture Mechanics, 103, 102251, 2019, Luca Di Stasio, Janis Varna, Zoubir Ayadi

Correlation microscopic / macroscopic behavior considering the heterogeneity of materials. Study of the Representative Elementary Volume (coordinators: Thomas Schenk, Marc Ponçot, Isabelle Royaud)

The group draws on its skills in matter physics (crystal defects in macromolecular architecture), to develop original coupled mechanical characterizations (diffraction, spectroscopy, etc.) with modeling of mechanical behavior.
It is based on experimental laboratory resources, from the atomic scale (MET, SEM) to the molecular scale (Raman spectroscopy) and on real-time in situ diffraction using large synchrotron type instruments at the mesoscopic scale.
To achieve their objectives, the team continues to develop original experimental devices, such as:

• its high temperature in situ mechanical testing machine under synchrotron radiation, which allows access to the 1300 ° C-1600 ° C temperature range to study new materials at very high temperatures, under more complex stressing modes
   
• its full field measurements
   
• its videometric control of mechanical tests
   
• its bulge test of thin metallic or polymer membranes (with 3D stereocorrelation)
   
• their multi-technical couplings: WAXS, SAXS, DSC, Raman spectroscopy, dynamic dielectrical analysis, tensile test, X-ray tomography with synchrotron radiation

Projects:

• Arcelor Mittal
• Nippon Steel

Theses:

• MESR, Adrien LETOFFE (2016-2020)
• MESR, Roxane TREHOREL (2015-2018)
• LabEx DAMAS, Komlavi SENYO ELOH (2017-2020)

Articles:

• Resilience improvement of an isotactic polypropylene-g-maleic anhydride by crosslinking using polyether triamine agents, Polymer, 179, 121655, 2019, Adrien Létoffé, Sandrine Hoppe, Richard Lainé, Nadia Canilho, Andreea Pasc, Didier Rouxel, Rafael J. Jiménez Riobóo, Sébastien Hupont, Isabelle Royaud, Marc Ponçot

High temperature in situ experimentation with synchrotron radiation. New high-speed measurement techniques and modeling

Examples:

• Studies of the creep of metallic materials using in situ X-ray diffraction of synchrotron radiation and high temperature furnace
   
• In-situ and in-operando studies of microstructure and mechanical behavior under load of metals and alloys
   
• Study of elementary deformation mechanisms in situ using synchrotron radiation during the creep of high resistance / high temperature alloys
   
• Modeling of diffraction peaks with the fast Fourier transformation method (FFT): in order to compare the results of theoretical mechanical simulations and experimental X-ray diffraction data

Coupling in situ Raman spectroscopy and videotractionTM for the study of polymer deformation

Examples:

• Study and understanding of the macroscopic mechanical properties of polymeric materials (VideotractionTM and 3D stereocorrelation)
   
• In situ monitoring of polymer deformation by Raman spectroscopy (evolution of the orientation factor, the crystallinity ratio and the volume damage)
   
• In situ experimentation in the study of polymers by combining simultaneously synchrotron radiation X-rays, videometric traction test (VideoTractionTM) and Raman spectroscopy

Determination of the link between defects and mechanical properties of composites (three approaches: experimental, numerical and theoretical)

Example: Study of the damage of multilayer materials in composite materials

Characterization of the physical properties of metallic materials, polymers, composites and biomaterials

• Plasticity, damage, aging / durability of materials
   
• Multi-scale characterization (mechanical and structural) of innovative materials for different societal challenges (energy, transport, health, environment)

Examples:

• Study of the mechanical properties of multimaterials (metals, polymers and composites) through the study of deformation mechanisms
   
• Determination of a plasticity limit criterion for polymer membranes: mechanical swelling test (bulge test)
   
• In situ study of the microstructure of polymers by X-ray diffraction in synchrotron radiation
   
• Study of the mechanical properties of polymers by videometric tensile tests (VideoTractionTM)
   
• In vitro study of the mechanical properties of biomaterials
   
• Study of the influence of the charge rate of composite odontological resins (fluids) on the mechanical and physico-chemical properties of materials
   
• Microstructural characterization of metals and alloys

Technology transfer

Creation of the start-up ProViSys Engineering in order to enhance and transfer the experimental know-how of the team (patents: VideotractionTM 2002 and Coupling of VideotractionTM and Raman spectroscopy 2011) http://www.provisys-eng.com/ Fr/

Professors, assistant professors

• Zoubir AYADI
• Rémy BALTHAZARD
• Abdesselam DAHOUN
• Yves MESHAKA
• Eric MORTIER
• Marc PONCOT
• Isabelle ROYAUD
• Jean-Philippe TINNES

PhD students

• Oumaima FAKRAOUI
• Maïté FERNANDES TRONCO
• Ablam MASSA
• Sreelakshmi MOOZHIYIL PURUSHOTHAMAN
• Hugo PIERSON-REMY

Post-doctoral researchers

• Jissy JACOB

Emeritus

• Gérard MICHOT