Nanoindentation (NI) and atomic force microscopy (AFM) nanoindentation, coupled with polarized light microscopy (PLM), were used to determine the nano-/micromechanical behavior of the amorphous regions and individual crystalline structures, both spherulites and transcrystalline (TC) layers, in PEEK samples containing few carbon fibers. To this aim, thin model samples with a controlled thickness were manufactured to allow both microstructure characterization in transmission mode and indentation tests without substrate effects.

The prediction of the micromechanical response of fibre-reinforced polymer composites with numerical models relies on the assumption that the matrix behaves like a bulk sample of the same polymer. Yet, the presence of fibres likely impacts the thermochemical history and mechanical behaviour of the matrix (e.g. formation of an interphase during processing). In this work, micromechanical analysis of a thermoplastic polymer matrix is performed on glass fibre-reinforced composite samples manufactured by vacuum infusion and in-situ polymerisation.

The Young's modulus and fracture strength of single and bilayer graphene (BLGr) grown by chemical vapour deposition (CVD) were determined using atomic force microscopy-based membrane deflection experiments. The uncertainty resulting from instrument calibration and the errors due to the experimental conditions like tip wear, loading position, and sample preparation were investigated to estimate the accuracy of the method. The theoretical estimation of the uncertainty on the Young's modulus linked to the calibration is around 16%.

Nanomechanical measurements of minimally twisted van der Waals materials remained elusive despite their fundamental importance for device realisation. Here, we use Ultrasonic Force Microscopy (UFM) to locally quantify the variation of out-of-plane Young's modulus in minimally twisted double bilayer graphene (TDBG). We reveal a softening of the Young's modulus by 7% and 17% along single and double domain walls, respectively. Our experimental results are confirmed by force-field relaxation models.

Multiscale mechanical modelling aims at predicting the failure of composites from the fibre/matrix level up to the component scale. Existing frameworks are limited by the lack of reliable experimental data and by an incomplete understanding of the submicron deformation and failure mechanisms. A novel digital image correlation (DIC) method has been developed for the characterisation of the nanoscale mechanical response in composites, based on latest advances in surface patterning.