bioCOMP4acoustics - Recyclable sound-absorbing composites with viscoelastic coated carbon+natural fibers and bio-based vitrimer matrix (copy)

Fiber (sandwich) composites in the aircabin have so far been optimized for economical, ultra-lightweight construction and are currently based almost exclusively on petrochemical raw materials for resin and fibers - bio-based and recyclable materials are missing. Low noise levels as a basis for good speech understanding are achieved in this sandwich structure by sound-absorbing glass wool between the cabin wall panels and the aircraft's outer wall as well as through the surface of the panels - with decreasing success in smaller aircraft. The implementation of innovative biomimetic concepts, i.e. a composite structures with a (visco-)elasticity gradient in the fiber and component wall thickness, has potential for noise reduction. An important prerequisite for such next-generation materials is high sustainability, i.e. (i) use of predominantly bio-based materials with (ii) easy recyclability of all valueable materials. However, taking into account the essential requirements of (iii) achieving at least the same, but optimally 10% reduced component weight ("climate-friendly aviation") and (iv) meeting the approval requirements (including flame resistance), these are missing so far. bioCOMP4acoustics closes this gap with (v) additional avoidance of toxic state-of-the-art fire retardants through R&D on 1. new resins from bio-based raw materials (i.e. vitrimers with dynamic covalent networks) with (i) processing in state-of-the- art prepreg and autoclaving processes, (ii) fire resistance through bio-based organic phosphates and (iii) solubility of polar solvents for the ecological separation of dissolved matrix monomers from fiber structures and fabrics in recycling, 2. hybrid natural (flax) & carbon fiber reinforcement with sub-micron thin hydrophilic, highly viscoelastic and adhesive coating with atmospheric pressure plasma and ultrasonic spray technology, as well as on 3. extensive mechanical material characterization on the nano to macro scale for data generation for simultaneous vibroacoustic & strength simulation for innovative gap closure between micro to macro scale in the design of ultra-lightweight sandwich composites with high acoustic damping. The choice of raw materials, processes and simulation models is based on the partners' high level of know-how (innovative composite and roll-to-roll coating technology), the joint development under specified certification requirements and under use of existing system technology. The aim as future user of the results for quieter, more sustainable aircabins and as its OEM supplier is to construct a demonstrator based on the previously developed innovative material, simulation and process toolbox. This toolbox ("digital element construction kit") also includes validated vibroacoustic simulation and ultimately enables specific topography-optimized component design while maintaining the boundary constraints of materials and production. An initial integration as a prototype into business aircraft with a simpler certification process than commercial aircraft, but higher customer demand for sound insulation, is planned 3 years after the successful end of the project.