Composites: a world first to measure deformations at the nanoscale !


Digital image correlation (DIC) allows 2D mapping of the deformations occurring in a material, by tracking the displacements of a speckle pattern deposited on the specimen surface.

The spatial resolution of the strain fields calculated with DIC depends on that of the speckle, and good-quality nanometric patterns are particularly challenging to obtain.

By relying on the technique of e-beam evaporation of indium - technique which has the ability to form discontinuous “islands” onto the substrate material and implemented within the WINFAB platform -, ultra-fine speckle patterns were successfully deposited onto carbon and glass fibre reinforced polymer composite surfaces.

In-situ compression testing of the speckled specimens was performed with a Scanning Electron Microscope (SEM) within the LACaMi platform, and the acquired images enabled the first nanoscale DIC measurements on this type of material.

This new method will hopefully help shed light on the local deformation and fracture behaviour of composites at the fibre scale, which is crucial for designing accurate finite element models of these materials throughout the lengthscales.


This achievement was made possible by the team work of two IMAP PhD students, Nathan Klavzer and Sarah Gayot (supervisor : Pr Thomas Pardoen), and a Senior Researcher, Michaël Coulombier.
This work was recently presented at the European Solid Mechanics Conference (ESMC) in Galway, Ireland, and received the Euromech Young Researcher Award among 500 candidates.

From the original article: "Nanoscale digital image correlation measurements on composites: a world first achieved in LACAMI and WINFAB !"

Published on December 01, 2022