Inspection and Maintenance are important aspects when considering the availability of aircraft for revenue flights. Modern airframe design is exploiting new exciting developments in materials and structures to construct ever more efficient air vehicle able to enable smart maintenance including self-repair capabilities. The improvement in the aircraft safety by self-healing structures and protecting Nano fillers is a revolutionary approach that should lead to the creation of novel generation of multifunctional aircraft materials with strongly desired properties and design flexibilities. In recent years, the development of new nanostructured materials has enabled an evolving shift from single purpose materials to multifunctional systems that can provide greater value than the base materials alone; these materials possess attributes beyond the basic strength and stiffness that typically drive the science and engineering of the material for structural systems. Structural materials can be designed to have integrated electrical, electromagnetic, flame resistance, regenerative ability and possibly other functionalities that work in synergy to provide advantages that reach beyond that of the sum of the individual capabilities.
Materials of this kind have tremendous potential to impact future structural performance by reducing size, weight, cost, power consumption and complexity while improving efficiency, safety and versatility. Actually, also a very advanced design of an aircraft has to take required inspection intervals into account. An aircraft with inherent protective and smart abilities could help to significantly extend the inspection intervals, thereby increasing aircraft availability.
The main objective of IASS is to develop and apply a multifunctional autonomically healing composite for aeronautic applications. The multifunctional composite systems will be developed with the aim of overcoming serious drawbacks of the composite materials.
The elixir of life for aeroplanes
Defects in aircraft structural components can cause extended downtime for maintenance and repair in the best case scenario, and accidents with catastrophic consequences in the worst. Novel self-healing composites will revolutionise aircraft structural components.
Advances in materials science in recent years have produced multifunctional composites combining traditional strength and stiffness with properties such as flame resistance or sensing capabilities. EU-funded researchers are exploiting the potential of multifunctional composites for self-healing through work on the project 'Improving the aircraft safety by self healing structure and protecting nanofillers' (http://www.iass-project.eu/ (IASS)).
The novel composites are slated to enhance reliability and service life and decrease accidents by up to 80 %, while slashing operating costs in half. In addition, they will decrease the size, weight, cost, power consumption and complexity of aircraft systems. This will have important impact on fuel consumption — also related to operating costs — and associated emissions.
Scientists are utilising inexpensive materials in ring-opening metathesis polymerisation-based chemical reactions that induce self-healing. Conductive forms of carbon, including multi-walled carbon nanotubes, carbon nanofibres, graphite forms and graphene sheets, are used to form both the conductive network and the catalyst support for the reactions.
The team has formulated and characterised the epoxy mixture and the nanofillers have been embedded in the epoxy matrix as part of the novel self-healing carbon fibre-reinforced composites (CFRCs). Scientists have modified formulations to enhance epoxy hardness and impart flame resistance as well. One of the most promising multifunctional load-bearing systems has been used to manufacture a CFRC panel.
Self-healing epoxy formulations have been tested under various processing conditions. Healing efficiency and dynamic mechanical properties are both critical to increasing the safety and reliability of the panels. These properties have been measured and are close to specified requirements. Formulations and panels will be optimised in upcoming months.
Exploitation of IASS self-healing multifunctional composites will have major short- and long-term benefits for the aerospace industry and its passengers. Self-healing of damage will keep safe planes in service, drastically reducing both disruptions to passenger travel and operating costs related to maintenance and downtime. This will have major positive impact on the competitive position of the EU aircraft industry and its role in a constantly growing market.