PhD Topic : Development and study of laminated composite material with Carbon NanoTubes functionalization dedicated to lightweight and damage-tolerant structures
Thanks to their mechanical, thermal, and chemical properties, composite materials have significantly contributed to weight reduction in the transportation sector. To further enhance weight savings while maintaining durability and multifunctionality, the development of composite structures relies on new or modified materials. Many research efforts aim to overcome these technological barriers through material functionalization, particularly by incorporating Carbon Nanotubes (CNTs) to enhance mechanical and physical properties. However, the potential of CNTs must be further explored by considering the specific targeted functionalities and associated failure modes (i.e., damage mechanisms).
This thesis aims to investigate the relationship between CNT integration methods and the resulting damage processes from the nanoscale to the macroscale, under severe environmental and loading conditions. Two specific scenarios will be studied: (1) thermomechanical loading at cryogenic temperatures, relevant to linerless composite vessels, and (2) post-impact fatigue loading, relevant to applications requiring high damage tolerance.
An initial phase, conducted by the CNES in collaboration with the Laboratoire Edifices Nanométriques (LEDNA) at CEA, CMP Composites company, and the I2M laboratory, aiming assessed to identify the most effective CNT integration method in laminated composites for cryogenic launcher tanks (using cyanate ester resin). Three processes and corresponding layered composite development protocols were investigated, (i) transfer of aligned CNTs mats by hot pressing (ii) dispersion of entangled CNTs mixed with resin, or (iii) CVD growth of nanotubes aligned directly on the dry ply.
The goal of this doctoral research is to consolidate the material functionalization approach using CNTs (in terms of shape, density, etc.) and to deepen the understanding of the mechanical behaviour of CNT-integrated layered composites. Depending on the loading scenario, appropriate tests will be conducted to assess the influence on damage mechanisms, compared to the same material without CNTs. The characterization will primarily rely on experimental observations across multiple scales, including in-situ (under loading) observations. Numerical modelling or hybrid approaches may also support the interpretation of observed phenomena. Depending on application requirements, several fibre/matrix combinations may be considered.