HyFiSyn’s key innovation is its interdisciplinary and holistic approach. It brings together materials scientists, mechanical engineers, polymer chemists and process engineers to jointly tackle the challenges in the field of fibre-hybrid composites. The emphasis on training ESRs to develop both modelling and experimental skills strongly differs from the traditional approach in this field and catalyse progress and increase the innovation capacity of the ESRs and the EU as a whole.
WP1: Simulation tools for microstructural design
KUL developed finite element models for debonding around fibre breaks, incorporated this into a longitudinal tensile failure model, and extended it to include fatigue damage. DTU used a model to correlate the experimental single fibre strength distribution to the strength of composites and found good agreement. KUL developed mesoscale models for the compact tension test, to better understand how the interaction between 0° and 90° plies governs crack growth. EPFL developed a mesoscale model to predict the translaminar fracture toughness based on measured bundle pull-outs. BMW developed macroscale models to better understand dynamic and quasi-static crash behaviour of hybrid car parts. UNott and NTPT developed process models to better understand fibre alignment and tow spreading processes.
WP2: Experimental characterisation for input and validation
KUL and DTU characterised the strength distribution of a range of glass and carbon fibres. KUL also characterised the stress-strain behaviour of two epoxy systems by performing tension and compression tests. Interfacial characterisation tests were planned but failed to materialise due to the pandemic. BME and EPFL measured relevant interlaminar and translaminar fracture toughness values. All these properties were used as input parameters in various modelling activities. A wide range of fibre-hybrid composites was tested in tension, bending and impact. This creates a large database of results that led to a better understanding of the mechanical behaviour of fibre-hybrid composites.
WP3: Manufacturing of novel microstructures
Tow-by-tow spreading was found easy to implement in existing processes, but the dispersion remains limited. NTPT revealed that calandering dissimilar thin ply prepregs is able to achieve excellent dispersion at a moderate cost. KUL developed an approach for 3D printing complex microstructures that are able to increase the translaminar fracture toughness of fibre-hybrid composites. Sioen used their looms to create custom hybrid weaves of self-reinforced composites hybridised with reinforcement fibres.
WP4: Smart & functional composites
Imperial developed morphing composites that have shape memory, controllable stiffness, and intrinsic heating. A proof-of-concept structure that was initially flat was able to deploy into a mesh. UVienna upscaled electrophoretic deposition strategies to create the anode and cathode. This yielded structural batteries and supercapacitors with improved energy storage capabilities. BME extended damage sensing capabilities compared to their existing patent, and improved interlaminar fracture toughness so that pseudo-ductile behaviour is achievable even for thicker plies. Intrinsic reparability was demonstrated in discontinuous layer hybrid laminates by thermoplastic film interleaving.
WP5: Recycling & alignment
Gen2Carbon undertook trials to better understand and optimise the use of pyrolysis for recovery of glass and carbon fibre from waste composite material. They also developed a separation method based on tribo-electrostatic charge to separate recycled carbon and glass fibres. UNott have upscaled and improved a rotating drum process to align short, discontinuous. This enables them to produce aligned fibre preforms at high production rates and with complex microstructures.
In addition to training 13 young researchers, HyFiSyn gained further insight into optimising fibre-hybrid composites, overcame some of the usual limitations of composites, and introduced new functions. Finally, recyclability of these materials was addressed and solutions were found to recover costly carbon fibres.
