Multifunctional Layers for Safer Aircraft Composite Structures
How the project will enhance the state-of-the-art
Current methods
Ice protection
- Electrothermal system, where heat is applied by flexible pads adhesively bonded on the surface of composite structure, or molding heating element (foil, film, resistance wire or mesh) into the surface of the composite structure during manufacturing process.
Fire protection
- Use of additional thermal barrier coatings on the structures.
- Chemical reformulation of matrix.
- Addition of additives and fillers into the matrix.
Health monitoring
- Fiber optic or piezoelectric sensors embedded into the composite structure.
Technical limitations
and issues
- Additional temperature sensors are required.
- They add laborious operations and manufacturing complexity during the component manufacturing.
- They require intense inspection and maintenance to make sure that they will function properly during precarious phases.
- Important weight increase (1-2 kg/m2), electric power consumption (11-49 kW/m2) and aerodynamic performance penalty. For that, it is not possible to use for all aircraft composite structures.
- Element burnout is of concern since no regulation exist and failure is total.
- The barrier coatings must be periodically inspected, repaired and maintained in very good conditions in order to maintain their effectiveness.
- The fillers have in many cases negative influence on the processability and mechanical properties of the resin itself.
- Chemical reformulation of the resin only achieves a partial improvement of fire properties. Combination with other method is required.
- Fiber optic diameter in many cases acts as stress concentration site, gives low strength at fiber-splicing locations, and they need for electro-optical signal conversion modules
- Piezoelectric sensors have low induced strain capability, high density, brittleness and limited fatigue life.
LAYSA improvement
- Temperature sensors are not required, because of self-sensing capability of the layer.
- Important saves due to simplification of manufacturing processes and maintenance operations
- No aerodynamic performance penalties
- Important weight reduction due to elimination of heavy heating elements. Possibility of heating all aircraft composite structures
- Element bourn out is not of concern because of improvement of fire resistance
- Reduction in power consumption due to unsurpassable current density of considered nanomaterials
- With respect to all methods, improved fire behaviour.
- With respect to barrier coatings, important saves due to simplification of manufacturing processes and maintenance operations
- With respect to fillers, easiness of manufacturing process and weight reduction
- The new integrated system does not have any detrimental effect on the structure and does not suffer by fatigue related problems.
- It will be possible a continuous health and usage monitoring and self-inspection; summarizing, a "smart maintenance" will be achieved.
As conclusion, the incorporation of ice /fire protection and structural health monitoring systems on composite structures result in adding 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.
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