Skip to main content

Hierarchical multifunctional composites with thermoelectrically powered autonomous structural health monitoring for the aviation industry

Periodic Reporting for period 1 - HARVEST (Hierarchical multifunctional composites with thermoelectrically powered autonomous structural health monitoring for the aviation industry)

Reporting period: 2018-09-01 to 2020-02-29

HARVEST is a MG-1.4-2017 36-month project that employs breakthrough technologies towards the realisation of two demonstrators with inherent thermoelectric energy harvesting capabilities. It will combine hierarchical Thermoelectric Energy Generating (TEG) reinforcements with novel matrices (3R: Repair-Recycle-Reprocess technology). The multifunctional TEG- structural composites of HARVEST aim at the Aeronautics sector.
HARVEST utilises the waste heat generated at specific sites on the airframe. The transport sector is a major contributor to waste heat, as only 20% of the fuel's energy ends up as useful energy. Aeronautical structures exhibit low energy efficiency as roughly 75% of the combustion energy produced is lost in the form of heat. The TEG-enabled materials of HARVEST will allow the conversion of otherwise lost thermal to electrical energy.
HARVEST encompasses a variety of technologies including:
• Design and development of a novel Roll-to-Roll line for producing prepreg with hierarchical fibre reinforcements and novel resin systems.
• Printing/coating of fibre tows and fabrics with nanomaterials via optimised deposition methods in a continuous process.
• Impregnation of fibre reinforcements with either plain or nano enhanced 3R matrices combining Repair-Recycle-Reprocess .
• Architectural design of TEG enabled laminates with thermoelectric outputs able to power up an electronic circuit.
• Design and development of the electronic circuit with user friendly software to store the TEG energy to (i) acquire SHM data via monitoring inherent sensing functionalities and (ii) wirelessly transmit data realising an autonomous SHM system.
• Development of predictive modelling tools to (i) model TEG materials, (ii) assist in the design and optimization processes, (iii) identify suitable heat sink locations in aeronautical structures and (iv) assess the TEG efficiency.
• Manufacturing and validation of two Demonstrators with thermoelectrically powered autonomous SHM.
• The novel developed technologies will increase aircraft safety and operational efficiency and reduce environmental impact via (i) introducing autonomous technologies towards “maintenance free” concepts, (ii) applying green energy concepts for waste heat management, (iii) reducing weight via the decrease of wiring (iv) decreasing life cycle costs (LCC) via multifunctionality.
HARVEST kicked off by defining the roadmap for its whole duration based on the selection of the two demonstrator parts. The first demonstrator will be a planar leading edge, manufactured in the autoclave. The thermoelectric energy harvesting will take advantage of the in plane temperature gradient. The second demonstrator will be a tubular structure manufactured by filament winding. In this case thermoelectric energy harvesting will be performed in the through thickness direction. For both demonstrators the 3R epoxy resin with carbon fibre tows/tapes will be employed.
HARVEST activities started with the finalisation of the design, the development and the installation of the R2R coating and prepreging line by FOM partner at the premises of the University of Ioannina (UOI). In parallel, UOI and NANOCYL developed the nanoparticle ink formulations, consisting of SWCNTs or Te based nanoparticles. CIDETEC studied and optimised the nanomodified 3R resin formulation for increased thermal conductivity. BNT successfully manufactured a 3R tubular part with filament winding. Coated carbon and glass fibres were assessed for TEG-efficiency at tow and fabric level. Tow pull out tests were employed on Model TEG-enabled 3R tows to test interfacial properties.
Initial testing showed that the best route to introduce hierarchy is via coating the fabrics with oxidised MWCNTs (MWCNT-COOH). Hierarchy will selectively endow heat (in plane) and electrical (through thickness) conductivity for the planar and tubular demonstrator respectively. At the same time, a single system lamina will provide the TEG functionality (see Figure 1).This was decided so as to (i) decrease the consumption of SWCNT inks, (ii) ensure the interfacial efficiency of the TEG-enabled laminates, (iii) avoid metallic contacts for interconnection of laminae with and (iv) adopt a multi-element approach to reach the required voltage to drive the SHM electronics.
The R2R line was employed for the production of 3R carbon fibre prepreg (see Figure 2).
TELETEL (TELE) finalised the design of the electronic board for storing TEG energy for SHM and wireless transmission and produced a breadboard (Figure 3) for first trials with a TEG-enabled mock-up manufactured by UOI.
The mock-up demonstrator generated enough energy to power the board validating the the “system lamina” approach (Figure 4).
In parallel to the experimental campaign, multiscale modelling of the thermo-electrical behaviour of composite materials was performed by UNIVERSITY OF PADOVA (UNIPD). Models were developed for assessing the thermo-electric properties along the three principal material axes of the lamina. Eventually, a model was developed for the thermoelectric properties in the presence of off-axis damage in composite laminates.
An example of the output of the numerical analyses used for model validation is shown in Figure 5a. Figure 5b shows the very good correlation of analytical predictions and numerical results.
Dissemination, communication and exploitation activities as well as effective IPR management were concurrently planned. Communication tools were developed with particular attention to social networks. Participation in conferences and a dedicated dissemination session (9th EASN Conference, Ethnes) were performed targeting scientific audience and end users. An exploitation strategy and dissemination plan for produced foreground was copiled. Relative existing standards have been identified with a view to addressing certification and standardisation issues for the developed technologies. A Data Management Plan (DMP) accurately defined all procedures for making HARVEST data FAIR (Findable, Assecible, Interoperable, Reusable).
HARVEST will demonstrate radically new and beyond the state-of-the art technologies for Aeronautics and other sectors (automotive, naval, etc.) by the deployment of nano-enhanced intelligent structural components. These include:
• New designs of R2R lines for coating on non-planar and porous or fibrous substrates.
• Nanomaterial inks with thermoelectric functionality.
• New prepreg materials with innovative 3R resin and nanomodified 3R resin.
• Electronic circuit and user software for harvesting and managing thermoelectric energy.
• Novel models for coupled thermo-electrical properties and analytical constitutive relations including software with graphical interface either as a «stand alone» tool or as a module for existing FE codes.
• Physical, mechanical and functional properties of TEG composites and systems available to the scientific community as open access publications and in a dedicated data repository.
To the beneficiaries’ knowledge, none of the above is currently available in the literature or in the market and represent substantial progress beyond the state of the art. The implementation of TEG enabled materials constitute a significant step towards more efficient and safer technologies for tha Aeronautics but also for other industrial sectors.
TEG enabled lamina with 4 SWCNT thermoelements (left) and TEG-enabled top lamina concept (right).
R2R manufactured prepreg using carbon fabric UD tape of high quality and 3R resin.
a)Vector plot of heat flux in thermoelectric FE model, b)FE results & model prediction for Seebeck.
Electronic breadboard developed and used to validate the technologies of HARVEST.
Mock-up of TEG lamina–electronic circuit operation under in plane ΔT (for heatable leading edge)..