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Multifunctional Structures

Final Report Summary - MULFUN (Multifunctional structures)

The main objective of the MULFUN project was the development of highly integrated equipment using new multifunctional, high thermal conductive materials in aerospace applications.

The new concept provides a basis for integration of electrical, structural and thermal functions with simultaneous considerations of volume, mass savings as well as increase of reliability.

Scientific research objectives:
- to define the design techniques, tools and knowledge for MFS concept;
- to study the processing and design concepts by using high thermal conductive fibres;
- to define equipments, materials and design elements for integrated thermal elements as mini heat pipes;
- to evaluate the materials and integration needs for flexible electronics.

Technological research objectives:
- to assess the potentialities of MFS design concept for various applications;
- to integrate functional elements: electrical, thermal and structural;
- to use advanced modelling and simulation tools to design structures which include thermal and electrical functionalities;
- to develop a methodology for cost and weight reduction by re-engineering current electronic housings;
- fabrication of critical samples as technology breadboard for various applications.

Quantified objectives:
- To design, manufacture and validate a representative electronic panel based on MFS able to dissipate 20-40 W through its surface/volume, reduced in 30 % versus aluminium panel.
- To redesign, manufacture and validate an optimised phase array antenna lay-up for transport applications by using MFS achieving a weight reduction of 30 %, allowing its integration on the transport vehicle roof-structure.
- To redesign, manufacture and validate electronic power housing by using MFS with a thermal dissipation of 48 W through its lateral panels, being 30 % lighter than current aluminium housings.

The project was structured into eight Work packages (WP), as follows:
- WP1: MFS technology review
- WP2 & WP3: Structural panels with passive and active thermal control
- WP4: Integrated MFS breadboard: phase array antenna
- WP5: Power electronic housing
- WP6: Exploitation and dissemination
- WP7: EMC-EMI and radiation shielding: state of the art and selection of the approach to be followed
- WP8: EMC-EMI and radiation shielding: manufacturing, testing and validation.

During the project, four breadboards have been developed. The technologies required for the MFS design have been developed and successfully applied in the four prototypes. In all the cases, good mechanical, thermal and electrical performances have been obtained. EMC-EMI and radiation shielding aspects have also been considered.

Different approaches in order to obtain a shielding behaviour comparable to a 2 mm thick aluminium plate have been evaluated. Mass savings of around 35 % in the phase array antenna and around 65 % in the electronic box have been obtained. Therefore, the tasks and objectives of the MULFUN project have been successfully fulfilled.

The MULFUN project represents a first step in the development of the multifunctional structures. However, several aspects for future work have been identified:

- Thermal transfer between the electronics and the panel
- Temperature monitoring in order to evaluate the distribution in the panel
- Alternative cooling by using fuel-air on avionics
- Assess delamination and CTE for integration of active cooling devices into CFRP

- Tools for series production (thermoplastics, RTM), complex shapes (curved panels - CFRP sandwich for fuselage) stiffeners
- Assembly process: obtain higher conductivity through the thickness (bonding)

- Adhesives with less thermal resistance
- Nanomaterials for EMI / Radiation on monolithic laminate

- Adhesives with less thermal resistance
- Nanomaterials for EMI / Radiation on monolithic laminate

- Possibility of repairing the electronic circuits (removal of the electronics from the plate
- Methods of inspection

- Introduction of heat sinks in intermediate layers to increase the thermal dissipation on high power devices.