Vertically Aligned Ferromagnetic-fibre Reinforced (VAFeR) Films for Enhanced Damage Tolerant Composites

It is well established that delamination damage is the dominant failure mechanism in laminated composites. There have been numerous technologies proposed to address this failure mechanism, with many state-of-the art methods such as Z-pinning, tufting, nano fibre reinforcements all suffering from problems such as manufacturing challenges, inconsistent toughening performance and expensive materials and infrastructure costs. For this reason there has been very little commercial use of these technologies in industry. There is clearly a need for a low cost, consistent and widely applicable through thickness reinforcement technology for composite structures.
In this proposal a new concept is introduced which can deliver through thickness aligned micro-fibre reinforcements at the critical interfaces within a composite material. Using electromagnetic field alignment, ferromagnetic micro-fibres will be vertically orientated within a polymer resin film which can then be interleaved in a composite material during the standard layup process. During the cure process, the softening of the resin and the applied pressure will consolidate the layers, forcing the aligned reinforcements to penetrate the adjoining laminates, providing a mechanism which will significantly increase the fracture toughness of composite materials. With this approach, highly damage tolerant composite structures can be produced at a fraction of the costs relative to current technologies. Several practical and scientific challenges will be investigated in three key objectives:
(1) Identify ferromagnetic micro fibre materials with high magnetic field susceptibility, high stiffness and strength and compatible with a suitable thermosetting resin system
(2) Produce VAFeR films with capability to control various operating conditions for alignment and integration of the micro-fibres within a partially cured thermosetting resin film
(3) Investigate effect of micro-fibre length and volume content on the mechanical performance of composite laminates with the application of the VAFeR films
This is an exciting opportunity to develop a new cost effective procedure with capability to significantly increase the damage tolerance capability of composite structures, a potentially transformative prospect for the UK composites research and industry.

Reducing weight of structures is a key target in improving fuel economy and reducing greenhouse gas emissions of transport vehicles. To meet these targets the aerospace and automotive industries have identified composite materials as the material of choice for their structures.
Impact damage is often the limiting design criteria for the UK Ltd in high technology sectors such as aeroengines, advanced aircraft structures, wind turbines, F1 racing cars, etc. To overcome this problem, composite structures must either be over-designed resulting in heavier and bulkier vehicles or a toughening technology must be applied.

This project offers new approach to improving the damage tolerance of composites through a low cost through thickness reinforcement (TTR) technology. The success of this proposal will allow improved design and safer use of composites in service, reducing the development and operating costs of enhanced damage tolerant composite structures and help maintain UK's technical edge in composite design and manufacturing.

Current state-of-the-art technologies used for toughening enhancements of composites require major capital investment in equipment and expertise. This results in a very long and expensive product development cycle. This proposal will overcome this problem by introducing a new toughening mechanisms which can be integrated with standard manufacturing processes used in the composites industry, significantly reducing the risk involved in adopting new technology. This means smaller enterprises and non-aerospace industries such as manufacturers of wind turbines, high performance sports equipment (bicycle frames, racquets, hockey sticks etc.), marine vehicles and the defence sector can all benefit from this proposal