Advanced EnerGy-absorption Polymer for Impact-resistant Smart composites

Project: Research council

Description

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.
StatusActive
Effective start/end date1/11/1930/04/21

Funding

  • Engineering and Physical Sciences Research Council