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Eco Design: Composite functionalization: thermal and electrical conductivity

Periodic Reporting for period 3 - ECOFUNEL (Eco Design: Composite functionalization: thermal and electricalconductivity)

Período documentado: 2020-05-01 hasta 2020-09-30

The substitution of metal parts by composite materials in aircrafts is a key approach within the general trend of improving the fuel efficiency and meeting environmentally friendly designs. Metals are heavier than composites and very usually require hazardous treatments to maintain their properties in acceptable levels that should be removed from the production line. Also, carbon fiber based materials present extremely high specific mechanical properties allowing for a significant weight optimization.
Actually, the application of composite materials is not only restricted to primary structure elements, but more and more metal components of the systems of the aircraft are being manufactured now in composites. However, the intrinsic properties of metals such as electrical conductivity are challenging the progress in the “carbonization” of some elements. Thus, the manufacturing of these parts in composites needs of novel material developments and strategies to meet all the requirements.
The environmental control systems (ECS) are essential systems of the aircraft that require of high electrical conductivity to discharge the static electrical charges produced during operation. Currently, some of the ducts of the ECS were successfully manufactured in polymer compounds. Nevertheless, the limited electrical conductivity of the composites that can be employed implies the use of metal braids to assure electrical continuity of the device, which add weight to the system. In this scenario, the ECOFUNEL project aimed to create new enhanced compounds with the objective of suppressing the extra weight of the braids. The technical approach for accomplishing the objectives included the use of specific fillers for the compounds in combination with reinforcements that enabled the enhanced electrical feature while keeping appropriate levels of mechanical properties.
The last samples were tested and the relevant deliverables were completed with the data obtained. An internal closure meeting was held on September 24th 2020 to review the last results, the remaining activities and the research outcome of the Project. Moreover, the final publishable report was created and submitted to the Grant Management Portal. The technical achievements obtained during the works will allow Liebherr Aerospace SAS to implement the novel material in their ECS with the advantage of the enhanced electrical feature.
During the whole 44-month action, a set of novel material formulations were proposed and created to substitute the current commercial compounds employed in the manufacturing of ECS. The candidate materials were evaluated in some key properties such as electrical conductivity or mechanical performance. Among all, one final material was selected for the manufacturing of the real-scale prototypes, and its characteristics were evaluated and reported. The new compound obtained showed a five-fold increase of electrical performance as compared to the reference material with a limited decrease of only 15 - 20 % of the mechanical properties. The overall technical results were presented in the MATCOMP ’19 Congress and Liebherr Aerospace SAS as the Topic Manager is studying the protection and exploitation via patent.
The formulations achieved by the project establish a new line of injection grades with improved characteristics over the commercial ones, and more specifically, they open the door for the property customization of this line of materials. The use of the developed grades particularly by the Topic Manager will suppose a weight reduction of near 5 % in the whole ECS system due to the removal of the electric brides between components of the device. In addition, thanks to the joint research efforts of the Consortium members, the electrical capability of the compounds created was further improved by heat treatments leading to even more successful project results. This secondary outcome enables a new research line on the formulated compounds that brings a novel approach for electrical characteristics enhancement.
The ECOFUNEL outcome is clearly aligned with the societal interests in regard to a greener transportation through lower emission of pollutants, lower manufacturing residues and the total suppression of chromium treatments often employed in metal industry. Also, improving the characteristics of the composites empowers the competitiveness of the aeronautics sector of the European region and boosts the penetration of these materials to other systems of the aircraft and even to other transportation industries such as automotive and railways.
Actual prototype produced in ECOFUNEL project