A multiscale approach to damage and rupture in glasses

phd offer 2021-2024

Sciences and Engineering of Soft Matter (SIMM),
UMR 7615
Adress : ESPCI – 10 rue Vauquelin – 75231 Paris Cedex 05
Chair : Etienne Barthel
Supervisors : Etienne Barthel et Matteo Ciccotti
Contact : etienne.barthel (arobase) espci.fr et matteo.ciccotti (arobase) espci.fr
https://www.simm.espci.fr – ED397 (Physics and Chemistry of materials - SU or PSL)

Keywords : amorphous materials, micromechanics, rupture
Fields : materials sciences or mechanics of materials, experimental
Funding : Agence Nationale de la Recherche (ANR) - income : 1900 € after taxes, 3 year contract

 
Background: It has been known for precisely 100 years that brittle materials fail due to surface defects. What is less known is how these defects are formed. For example, it is not well understood why, among many silicate glasses with otherwise very similar mechanical properties (elasticity, resistance to frac-ture propagation, hardness), some are much more resistant to crack initiation than others (Fig. - 3). The reason must be found elsewhere and we have recently suggested that the culprit is probably the material sensitivity to the localization of plastic deformation [1] as manifested, for example, in the formation of shear bands (Fig. - 1).

Project : The difficulty is that the material is brittle and therefore it is necessary to work at small scale (around 10 μm). In this project, we will develop an original experimental approach coupling optical measurement of deformation fields (Fig. - 2) with local mechanical tests, in particular in micropillars (Fig. 1) and indentation (Fig. - 2 and 3). Based on these experiments, we will try to establish relationships between material structure, mechanical properties, sensitivity to deformation localization and fracture initiation. The first objects of study will be epoxy resins, which are brittle amorphous polymers. This model system is very relevant since localization of plastic deformation is the main mechanism of strengthening in glassy polymers/elastomeric latex composites [2]. The methodology will then be applied to a few series of silicate glasses known to present a marked gradation of sensitivity to cracking [3]. Modelling carried out in parallel at INSA Lyon (G. Molnar & A. Tanguy) will also guide the experimental work and help to clarify the conclusions.

Progress and partnership: this thesis is part of the ANR GaLaad research project. Some specific experiments will require the development of dedicated set-ups, others will be carried out in two partner laboratories of the project (in situ compression at the Ecole des Mines de Saint-Etienne - G. Kermouche, Raman mapping at the ILM in Lyon - C. Martinet). Although relatively fundamental in nature, this project is also part of a long-term collaboration with two glass companies, Saint-Gobain Recherche (Aubervilliers) and Nippon Electric Glass (Shiga, Japan), with which the student will interact from time to time.

Candidate: good background in science or mechanics of materials, curiosity and a bend for original experimental approaches.

Bibliographical references:
[1] Indentation cracking in silicate glasses is directed by shear flow, not by densification
Barthel, E.; Keryvin, V.; Rosales-Sosa, G. & Kermouche, G., Acta Materialia 194 (2020) 473-481
[2 ] Modelling of the toughening mechanisms in rubber-modified epoxy polymers, Y. Huang & A. J. Kinloch, Journal of materials science 27 (1992) 2753-2762
[3] Mechanical properties of silicate glasses as a function of composition, R. J. Hand & D. R. Tadjiev, Journal of non-crystalline solids 356 (2010) 2417-2423

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Practical information

Sciences et Ingénierie de la Matière Molle

Soft Matter Enginering and Science Laboratory - UMR 7615

10 rue Vauquelin
75231 PARIS CEDEX 05
FRANCE

  • Chair : E. Barthel
  • Vice Chairs : J.B. d’Espinose & G. Ducouret
  • Administration : F. Decuq, M.-T. Mendy & M. Hirano-Courcot
  • Communication : A. Hakopian & M. Ciccotti
  • Information Technology : A. Hakopian
  • Safety, Health and Environment Assistant : F. Martin

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