Characterization and modelling of pre-gelation/gelation behaviour of polymer composites

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Polymer matrix composite materials have finally become significant materials in aerospace: the Boeing 787, Airbus A350, Bombardier C-Series all depend heavily on these materials. Likewise, the use of composites in the wind energy sector is now significant, and there is a major move to composites in automotive, led by BMW with their i3 and i8 series. In all cases, the ability to reliably manufacture complex structures as quickly and efficiently as possible yet control the quality of the process is critical. ***Process simulation (nowadays included in Integrated Computational Materials Engineering or Multi-Scale Modelling) was proposed very early on as a method to reduce risk and optimize processing of composites. Simulation has always been attractive for composites as the material and structure are essentially made at the same time; thus the complexity of the problem scales rapidly when faced with real parts and geometries.***This proposal is for fundamental understanding of manufacturing science of next generation composites for newer, faster, cheaper, more sustainable and greener processes including additive manufacturing.***The overarching objective of the proposed work is to develop a coherent and continuous description of the mechanical behaviour of (a) a thermoset resin from the uncured to the cured state, over a range of temperatures taking the material behaviour from glassy to rubbery (and fluid if pre-gelation). The behaviour of interest includes the viscous and viscoelastic response (viscosity, storage and loss moduli) as well as surface tension, cure shrinkage, and thermal expansion effects; and (b) a prepreg made of such resin, including the effect of initial fibre waviness (from the prepregging process) as well as the ability of the material to wrinkle in the pre-gelation state. The description of the material response should be the basis of compatible constitutive equations that describe the material response over this wide range of conditions. This will be a major advance on the current state of the art where the characterization of material properties has been done in a disjointed and scatter-shot manner, and major assumptions made.***The benefits of currently used first generation characterization of materials for first generation process simulations of residual stress and dimensional change are increasingly obvious. With the fundamental work envisaged in this proposal, we will broaden and deepen the fundamental characterization and representation of basic resin and prepreg behaviour over the range of materials and processes that will be of significant interest in the next decades. Only with a solid science base can advanced manufacturing become a reality.