Alessandra DEL MASSO : "Scaling transition between plant fiber and UD composite..."

PhD Work: Scaling transition between plant fiber and UD composite, propagation of variability and nonlinearities

Abstract:

Although plant-fibre reinforced composites (PFCs) represent an attractive solution for the design of lightweight, high performance and low environmental cost structures, their development requires in-depth studies of the mechanisms underlying their nonlinear tensile behaviour, as well as variability of mechanical properties. Given their multi-scale nature, this thesis aims to contribute, using a numerical approach, to the study of the propagation of behaviour across the scales of PFCs. Firstly, the study focuses on the fibre scale: a 3D model of the behaviour of the wall is first implemented in an EF calculation, in order to establish the influence of fibre morphology on the tensile behaviour. Once the non-negligible impact of the morphology has been determined, a study of the links between morphology, material and ultrastructure and tensile behaviour is conducted via a sensitivity analysis in the case of flax and hemp. The second part of the work is dedicated to the composite ply scale. A new stochastic multi-scale approach is developed and implemented. It is based on the definition of an elementary volume (VE) with random microstructure to describe the behaviour of the ply. The approach is then used to study the sensitivity of VE behaviour to nano, micro and mesoscopic parameters. Sensitivity analysis, conducted via the development of the response on the basis of polynomial chaos, allows us to construct a metamodel of the tensile behaviour of the ply.

Keywords: Plant fibres, Composites, Multiscale methods, Stochastic methods, Numerical modelling, Nonlinear behaviour

Jury :

- M. Patrick PERRÉ,  Professor, LGMP, CentraleSupelec, Univ. Paris-Saclay (Paris), France
- Laurent ORGÉAS,  CNRS Senior scientist, 3SR Lab, CNRS, Univ. Grenoble Alpes (Grenoble), France
- Philippe BOISSE,  Professor, Lamcos, INSA (Lyon), France
- Cécile MATTRAND,  Associate professor, Institut Pascal, SIGMA Clermont (Clermont-Ferrand)
- David SEVENO,  Associate Professor, MTM, KU Leuven, Belgique
- M. Vincent PLACET,  Ingénieur de recherche, Institut FEMTO-ST, UBFC
- M. Lamine BOUBAKAR,  Professor, Institut FEMTO-ST, UBFC
- Frédérique TRIVAUDEY,   Associate professor, Institut FEMTO-ST, ENSMM
- Violaine GUICHERET-RETEL,  Associate professor, Institut FEMTO-ST, ENSMM

Location : ENSMM, Amphithéâtre Émilie Du Chatelet, 26 rue de l’Épitaphe, Besançon