Recywind - Recyled carbon fibre in structural application

Performance bycicle frame made from rCF-material, built by V Carbon, SPIN and FHNW

Technologies

• Carbon fibre reinforced components
• Sustainability and circularity
• Re-aligned staple carbon fibre
  

Background

Carbon fibre composite materials (CFRP) are used in the automotive, aerospace, medical and sporting goods industries to achieve with maximum strength and rigidity with minimum weight. 30% of the CFRP raw material ends up as production waste and amounted to 32100 tonnes in 2022. In addition, less than 5 to 15% of CFRP waste is recycled at end of life (EoL), while 85 to 95% ends up in landfills or incinerators. Our innovation aims to promote the use of recycled CFRP, making it more cost-effective and reliable than the state-of-art.

Carbon fibre can currently reclaimed via pyrolysis. The reclaimed feedstock consists of short fibres, which can be used for injection moulding or for nonwovens. This product class offers distinctive material properties that are well above unreinforced compounds, but at the same time well below high-performance CFRP laminates. The lack of performance simply corresponds to the very low fibre volume content, reaching 35% for an isotropic nonwoven laminate. Therefore, it is a common believe in the composites industry that the potential of rCF products is limited in terms of technical feasibility and recycling costs.

Goals

The Recywind project aims to improve rCF semi-finished products in terms of their mechanical properties so they can replace virgin fibre material in structural applications. This would proof true circularity for CFRP-based composite materials. This vision is supported by the FHNW in a long-term collaboration with the company V Carbon GmbH and expanded through this project.

A performance bicycle frame will be built as technology demonstrator, to test the applicability of 2^nd-life material as a primary structure.

Results

As a starting point, the recycled material was mechanically tested to define knock-down factors for an rCF-specific design. Various industrial processes were investigated, namely film stacking, dry/wet filament winding, prepreg winding, wet pressing and the tube blowing process were explored.

Dry filament winding of tubular sections

The frame was tested for steering head stiffness and meets the prescribed minimum values. A bike was put together and tested on flat and steep terrain. The project was carried out by FHNW in collaboration with V Carbon GmbH in Switzerland and with the renowned German frame builder SPIN.

Preform compaction, vacuum setup and autoclave infusion