AEGIS (Advanced EnerGy-Absorption polymer for Impact-resistant Smart composites)

The development of a new generation of advanced fibrous composite materials plays a key role in the future evolution of the aerospace sector due to their very high weight-to-strength ratio that can lead to higher operating efficiencies per revenue passenger kilometre. However, while the fibre dominant properties guarantee excellent in-plane load-bearing characteristics, traditional composite materials exhibit weak resistance to out-of-plane loads, making them susceptible to delamination damage under impact loads that can happen during manufacturing or in service. Indeed, while for metallic media, which are homogeneous and can dissipate energy through yielding, a surface dent will only increase strain hardening locally, for composite materials it is associated with the separation of interior plies due to their intrinsic layered structure, and therefore it must be avoided since it can grow uncontrollably compromising the integrity of the entire structure and leading to severe local degradation of the mechanical properties and, in some cases, sudden critical failures. This weak impact resistance together with the complexity of the failure mechanisms typical of composite systems led in the past decade to the definition of the current design philosophy in aeronautical structures as a "no damage growth" approach, leading to overdesigned structures with high thickness and mainly quasi-isotropic layout based on the assumption of the presence of defects from the outset. Based on these premises, it appears clear the need of a comprehensive solution for the aerospace sector that matches the requirements of lightweight structures with the need for high impact resistance. AEGIS is aimed at the development of a novel hybrid composite material with exceptional energy absorption property which is based on the development of a new "smart" "pseudo non-Newtonian" polymer that can be used in traditional manufacturing processes of plate-like components and complex sandwich panels. The exceptional impact resistance of these new structures is caused by a dynamic stiffening effect given by the transient nature of a large number of crosslink bonds present in the new smart polymer, which forces the polymeric chains to dissipate a large quantity of energy in order to disentangle themselves when subjected to an external load. The development of this new polymeric layer will eliminate the issues associated with moisture absorption of traditional liquid media, allowing its efficient and rapid application on laminated structures as a "smart layer" that can be used as a superficial coating with a minimum effect on the final weight of the structure. Furthermore, due to the higher viscosity of the polymer, it will be possible to intercalate it within a scaffold material in order to develop a "smart core", guarantying ease of manufacturing and increasing the stiffness of the frequency-dependant polymer, leading to the development of novel hybrid sandwich structures.
The hybrid composite materials developed in AEGIS will be able to actively respond to specific external stimuli via dynamically enabling the entanglement of the polymeric chains only when the solicitations are above a critical threshold. By combining the exceptional in-plane specific properties of composite materials with the outstanding out-of-plane resistance of the smart polymer, AEGIS will tackle the current limitations of composite components leading to a general increase of the reliability of composite structures that can change the current design approach reducing the safety parameters and optimising the geometries of current components.

The development of the impact-resistant AEGIS composite laminates will translate to the reduction of the need of over-dimensioning components, shifting manufacturing paradigms towards cheaper processes and reducing production costs and maintenance. The main beneficiaries and the direct customers of AEGIS would be companies operating in the aerospace sector with different stakeholders placed at different positions within the production chain. In particular companies that are directly involved into the manufacturing of composite structures for the aerospace industry such as Airbus would benefit of the access to the technology related to impact-resistant laminates together with suppliers of raw fibrous materials and prepregs. This will be done through directly licensing the intellectual properties that will be developed during the AEGIS project and continued through subsequent co-development projects. The outcome of AEGIS would ignite the possibility to manufacture new innovative impact resistant structures that will allow UK industry to consolidate its competitive advantage in the field of composite structures aligning its objectives with the key areas of High Value Manufacturing and Transport system of the Catapult Programme.
As a secondary objective, by developing innovative smart composites and reducing manufacturing costs, the outcome of AEGIS will help expand composite materials into other new sectors where they have been traditionally hindered by design complexity, production costs and by the catastrophic nature of their failure mechanism. Indeed in order to expand the composite market towards mass-adoption, sectors like biomedical, railways and consumer goods industries need to address large technological (i.e. the intrinsic brittle failure of composite components) and cost-related gaps (i.e. overdesign and expensive manufacturing processes) that can be filled by the solutions proposed by AEGIS. In this, AEGIS will benefit from the support of the Research & Innovation Services of the University of Bath that will facilitate the technology transfer and help developing new relationships with industry and inter-disciplinary research collaborators. Together, these stakeholder not only will maximise the impact generated by AEGIS, expanding the adoption of its outcomes outside the aerospace sector, but they will also create a network of industries and research centres that will be able to foster new collaborations and promote new researches, fuelling R&D activities and attracting inwards investments from UK and EU.
In addition, the support of the SetSquared Business Incubator will facilitate the commercialisation process of the technology developed during the AEGIS project, offering a bespoke business support to help starting a spinout company providing specialisms and expertise in marketing, legal, IP and financial sectors.
In terms of the effect of AEGIS on society, the outcomes of the project will help shed light to the current limitations of composite materials. Improving resistance of composite materials, reducing the risk of catastrophic failures would change the manufacturing approach of composite materials, leading to lighter structures with lower CO2 footprint. This in turn will allow faster transportation systems with higher capacity and lower environmental impact, potentially improving everyday life of millions of people across UK and Europe. In addition, in view of the increase of 25% tariff on steel imports and 10% on aluminium from the US, the new market opportunities (both direct and indirect) generated by the insight on properties of smart composite structures can influence policymakers, defining new strategies in terms of existing regulations and prioritising investments in the advanced materials sector in line with points P2 and P3 of the "Productive Nation" prosperity outcomes included in the EPSRC's delivery plan 2019/20.