Periodic Reporting for period 2 - SUSTAINair (SUSTAINablility increase of lightweight, multifunctional and intelligent airframe and engine parts)
Période du rapport: 2022-07-01 au 2023-12-31
Commercial aviation contributes 2-3% of the world’s manmade emissions of CO2 with transportation as a whole producing ~24% according to the UN Intergovernmental Panel on Climate Change (IPCC). SUSTAINair is dedicated to improving the environmental impacts caused by an aircraft throughout its entire life cycle and taking up the challenge to foster innovation on Circular Economy by researching on application of recycled materials and optimized resource recovery. The project investigates novel assembly/de-assembly/repair/reuse of parts/subassemblies by intelligent combinations of modern joining and innovative materials technologies. SUSTAINair is addressing the major challenge of GREENING OF AIRCRAFT – in a way, that environmental benefits are meeting economic viability and European competitiveness at once. A large scale of synergies allows the consortium to focus on eight Key Enabling Technologies (KETs), each of which is targeting challenging Key Performance Indicators (KPIs). Validation of these KPIs will be performed individually per KET, but also in an integral manner by means of two demonstrators, reflecting the multi-material design philosophy, in which combinations of aluminium, titanium and FRP grades are used. SUSTAINair’s R&D is organized through five Specific Objectives, each implemented by a dedicated technical work package.
Start of the project was centred around progressing individual material technologies in combination with advancing processing routes to enable the projected recycling scenarios, based on a diligent definition of mechanical testing scenarios and general design requirements, to accord the potential in future aircraft applications. Intensive work was carried out on developing future cast and wrought aluminium alloys with enhanced recyclability. Wide ranges of intrinsic nanoeutectic as-cast alloys were screened by simulation and experimentally. Lab-scale and industrial scale casting was applied, with equivalent material properties. A first generation of performance-enhanced Al-Mg-Si alloys was produced and characterized. AM of Titanium powders was performed using virgin and recycled powder feedstock, first correlations between LPBF feedstock “age” and material performance could be obtained. CFRP upcycling development was performed for thermoset and thermoplastic secondary resources and a variety of recyclate grades from real production wastes were investigated for both material categories. First joining trials have been performed, for metal as well as thermoplastic and thermoset composites. Titanium samples with additively manufactured pins have been joined with thermoset composite sheets and single lap shear (SLS) tests have been performed. For the metal and thermoset composite parts, both 1st and 2nd life materials have been considered and a variety of process parameters screened. Next-gen SHM systems, damage modes and -propagation were analyzed, novel sensors and their structural integration progressed beyond state of the art. Potential SHM methods were reviewed, selected, further developed, and numerically and experimentally validated on component level. The original plan to provide beyond lab-scale proof of feasibility of the “automated rivet removal robot head” was re-defined relying on water jet cutting. The anticipated TRL level had to be reduced to actual lab-scale trials.
During P2 period, SUSTAINair partners have completed most of the technical tasks and started to transfer their findings to designing and manufacturing of 3 different demonstrators. WP1 provided a summary of requirements for the application of technologies and processes developed in the project demonstrators. Circular coupons and a test plan have been developed and completed. Further development of sustainable manufacturing, recycling and characterization of the processed materials was achieved. Rivet removal experiments have been carried out, including investigation in scanning techniques and cutting strategies for automated dismantling. Intensive studies were carried out on upcycling and the derived new recyclate materials were characterized and investigated, concluding in a LCA performed for the novel processes. SHM methods could be successfully demonstrated and used in the final cyclic tests with promising findings regarding the further sensor development. Extensive joining tests were performed, for metal as well as thermoset and thermoplastic composites and hybrid combinations, considering both first and second life materials. The strength of the joints was tested to quantify the performance of 2nd life materials compared to their 1st life counterparts. With M19 of SUSTAINair, the realization of a total of 3 different demonstrators started, showcasing the outcome from WPs 1-4. Manufacturing activities were initiated, alongside preparation of individual test plans and assessment of all demonstrator variants to take place in the final project period. DEC activities are progressing smoothly with increased presence at many relevant events and joined forces with sister research projects in the aviation sector.
During P2 period, SUSTAINair partners have completed most of the technical tasks and started to transfer their findings to designing and manufacturing of 3 different demonstrators. WP1 provided a summary of requirements for the application of technologies and processes developed in the project demonstrators. Circular coupons and a test plan have been developed and completed. Further development of sustainable manufacturing, recycling and characterization of the processed materials was achieved. Rivet removal experiments have been carried out, including investigation in scanning techniques and cutting strategies for automated dismantling. Intensive studies were carried out on upcycling and the derived new recyclate materials were characterized and investigated, concluding in a LCA performed for the novel processes. SHM methods could be successfully demonstrated and used in the final cyclic tests with promising findings regarding the further sensor development. Extensive joining tests were performed, for metal as well as thermoset and thermoplastic composites and hybrid combinations, considering both first and second life materials. The strength of the joints was tested to quantify the performance of 2nd life materials compared to their 1st life counterparts. With M19 of SUSTAINair, the realization of a total of 3 different demonstrators started, showcasing the outcome from WPs 1-4. Manufacturing activities were initiated, alongside preparation of individual test plans and assessment of all demonstrator variants to take place in the final project period. DEC activities are progressing smoothly with increased presence at many relevant events and joined forces with sister research projects in the aviation sector.
The concept of nanoeutectics was expanded into a wider phase space, linking the typical base system of automotive value streams, i.e. Al-Mg-Si with a significant share of the aviation EoL bandwith by actively utilizing large Zn-additions. Beyond, the method was also applied to incorporate Iron (Fe) as an active ingredient enhancing the alloys properties, thereby fitting the material composition to realistic EoL waste stream compositions. The resulting alloy, AlMg6Si2Zn3FeNi could meet the KPIs proposed. Further incorporation of Cu (and Mn) was outlined on basis of thermodynamic calculus. This would complete the projects overarching goal of providing a material for high performance parts from universal aluminium waste streams. A broad range of such alloys can significantly reduce Europe’s dependency on non-domestic primary Al resources, next to offering a three to fivefold direct reduction in processing energy consumption. Failure modes in recycled, hence by definition short fibre CFRP-materials impose unprecedented challenges towards robust design of such structures. By simultaneously advancing production routes and applying advanced characterization of failure in this materials, robust processing windows become available, elucidating the performance limits of fully recycled fibre reinforced materials. To enable the integral design of subassemblies in line with circular economy concepts, the focus of SUSTAINair is on welding and bonding techniques, thus replacing rivets at maximum. As could be proven on microstructural scale, e.g. nanostructured eutectic aluminium alloys show no weakening of joining interfaces. Structural assemblies that are to date milled from large precursors at immense material losses can be designed and produced by combining near net-shape at equal performance. Choosing the same base of alloys (Al-Mg-Si) for both cast and wrought substructures puts omitting rivets overall within reach in future generation aircraft. Next to advancing SHM and MRO methodology for all material classes described, realizing novel sensor generations that can be integrated into assemblies without reducing cyclability of structures in EoL will allow to reduce safety margins (in particular with respect to secondary feedstock utilization) in product/structural design without compromising safety.