Concept and Objectives:
The use of composite materials in aeronautics industry has increased constantly over the last 35 years, due mainly to their high specific strength and stiffness combined with the possibility of designing complex geometry components that are more aerodynamically efficient than metals. But due to organic nature of polymeric matrix component, composite materials are electrically and thermally bad conductors and they tend to burn easily, emitting toxic gases and smoke. For that, they require affordable, effective and certifiable protection systems against atmospheric hazards such as icing, as well as fire and burning in case of accidents.
Moreover, improved in field inspection techniques are required with the increased use of composite materials. Current technologies address those issues separately; ice protection is usually performed by mean of a metal mesh or foil incorporated into the outer ply of fabric on the skin of the structure, fire protection is performed with thermal barrier coatings on the structures and life monitoring is performed with embedded sensors. All of them add high weight penalty and complexity during the component manufacturing and posterior maintenance, even may go against the structural integrity of the component in some cases.
LAYSA Results in brief:
All-in-one structural monitoring and protection
Conventional aircraft structures employ a number of protective materials and monitoring systems for a variety of jobs. Scientists are developing multifunctional components integrating tasks for lighter and safer aircraft.
The aircraft industry increasingly uses composite materials due to their enhanced strength and light weight. In addition, they can be formed into complex shapes more aerodynamically efficient than metals. However, they are poor conductors of heat (or cold) and electricity. As a result, they can burn easily, releasing toxic gases and smoke and, conversely, enable ice formation. Ice protection is usually accomplished with a metal mesh or foil integrated into the structure whereas fire protection is performed with thermal barrier coatings.
Scientists initiated the EU-funded project ‘Multifunctional layers for safer aircraft composite structures’ (LAYSA) to develop a new layer providing both ice and fire protection, as well as structural health monitoring (SHM). SHM is currently accomplished with a third system, embedded sensors. The focus is on coupling changes in conductivity to thermal and stress measurements and developing modelling tools for design of multifunctional layers. The combination of the three systems into one promises to reduce weight, simplify manufacturing and maintenance, and perhaps even increase safety.
During the current reporting period, scientists optimised dispersion parameters and prepared or obtained all needed materials. These included nano-reinforcement dispersions, nano-doped resin films and buckypapers (thin sheets of carbon nanotubes). Scientists incorporated relationships between nano-scale structures and macro-scale properties into multi-scale models. They were used to predict electro-thermal behaviour, mechanical response and sensing performance of nano-reinforced polymer systems. Investigators also used the models to evaluate fire burn through a composite panel.
Based on the above experimental and theoretical results, the most promising materials and processes were identified and manufacturing commenced. After comprehensive testing and optimisation, two demonstrators were manufactured and guidelines developed for optimal performance and future research. Finally, scientists conducted a technical and commercial evaluation of the products to assess potential for transfer to industrial applications.
LAYSA expects to deliver high-performance multifunctional aircraft structures based on novel nanocomposites with exceptional thermal and electrical conductivity and sensing capacity. The structural elements will enable thermal protection and SHM in one system for safer, lighter planes with lower fuel and power consumption.