Nanomechanics serving polymer-based composite research

Abstract

Tremendous progress in nanomechanical testing and modelling has been made during the last two decades. This progress emerged from different areas of materials science dealing with the mechanical behaviour of thin films and coatings, polymer blends, nanomaterials or microstructure constituents as well as from the rapidly growing field of MEMS. Nanomechanical test methods include, among others, nanoindentation, in-situ testing in a scanning or transmission electron microscope coupled with digital image correlation, atomic force microscopy with new advanced dynamic modes, micropillar compression or splitting, on-chip testing, or notched microbeam bending. These methods, when combined, reveal the elastic, plastic, creep, and fracture properties at the micro-and even the nanoscale. Modelling techniques including atomistic simulations and several coarse graining methods have been enriched to a level that allows treating complex size, interface or surface effects in a realistic way. Interestingly, the transfer of this paradigm to advanced long fibre-reinforced polymer composites has not been as intense compared to other fields. Here, we show that these methods put together can offer new perspectives for an improved characterisation of the response at the elementary fibre-matrix level, involving the interfaces and interphases. Yet, there are still many open issues left to resolve. In addition, this is the length scale, typically below 10 micrometres, * Corresponding author.

High performance recycled CFRP composites based on reused carbon fabrics through sustainable mild solvolysis route

“…Nanoindentation tests were performed to investigate the mechanical behaviour of the near fiber/matrix regions of the virgin (reference) and recycled composites. Figure 6 shows examples of indents performed very near the carbon fibers, sometimes as close as 1 µm, while avoiding significant mechanical interaction with the fiber on the elastic and plastic strains 27 , 28 .

Figure 6 Optical images (40 × of magnification) of ( a ) reference and ( b ) recycled composite surfaces showing the indent point location (red circle).

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Implementation and calibration of a mesoscale model for amorphous plasticity based on shear transformation dynamics

“…We have also examined the sensitivity of the predicted deformation response by the STZ model to (Hardin and Homer, 2015;Sun et al, 2016Sun et al, , 2018Tong et al, 2016) or the examination of the stress-state of an epoxy matrix pocket in a fibre-reinforced composite (Pardoen et al, 2021).…”

“…In addition, they can be used to analyse the ductility of hybrid material systems comprising an amorphous phase (Choi et al, 2012;Rozanski and Galeski, 2013;Sun et al, 2016;Zhou et al, 2013). Excellent examples of such hybrid material concepts include (1) fibre-reinforced polymer composites and thin adhesive joints where the evolution of plasticity in the glassy polymer matrix or adhesive is sensitive to the degree of confinement (Lopes Fernandes et al, 2019;Pardoen et al, 2021Pardoen et al, , 2005Van Loock et al, 2019), and (2) metallic glass-based composites where the interaction of dislocations and STZ transformations at the interfaces between the crystalline and amorphous metallic phases may lead to an enhanced macroscopic ductility (Donohue et al, 2007;Hardin and Homer, 2015;Jiang et al, 2021;Phan et al, 2020;Sun et al, 2018;Wang et al, 2015;Zhao et al, 2021;Zhou et al, 2013).…”

“…From a more practical point of view, the selection of the values of the STZ model parameters based on measurement data remains a somewhat arbitrary curve fitting task to date (Chevalier et al, 2018;Homer and Schuh, 2009;Pardoen et al, 2021;Wang et al, 2018). An analysis on the sensitivity of the mesoscale STZ model's response to the values of its basic ingredients is essential to guide the parameter identification process, but has not been explored in detail so far.…”

Foreword: Plasticity and Solid State Physics

“…Plasticity and its challenges are not limited to metals. The case of polymer-based composites is addressed by Pardoen et al [19]. The authors show how nanomechanical testing methods combined with coarse graining modelling tools provide a new picture of nonlinear fiber-matrix interactions which finally lead to damage initiation.…”