The CARBIO project, led by Composites Evolution (Chesterfield, UK), has produced hybrid composites using layers of flax fiber and carbon fiber that the group claims have equal bending stiffness to all-carbon laminates, but with reduced cost, increased shock absorption and improved environmental impact.
The project has designed and manufactured a prototype automotive roof that combines the high strength and aesthetic appeal of carbon fiber with the low cost and vibration damping performance of flax. The prototype roof will be on display at the JEC World 2016 show (March 8-10; Paris).
In addition, the carbon/flax micro-sandwiches have recently been shown to perform very well in automotive sled impact tests. A 50/50 carbon/flax hybrid crush structure was reportedly found to have equal specific energy absorption to an all-carbon structure.
“We already knew that Biotex Flax could be used to reduce the cost and vibration of carbon fiber parts, but these outstanding impact test results came as quite a surprise to the R&D team,” said Brendon Weager, technical director at Composites Evolution. “These low cost, fail safe hybrid crash structures will be of significant interest to automotive and motorsport engineers.”
An alternative approach is to create hybrid fabrics, where the carbon and flax fibers are co-woven to provide tunable performance, vibration damping and unique aesthetics at a lower cost than pure carbon fabrics. One example is Biotex Flax/Carbon 180g/m2 2x2 twill, a drapable hybrid fabric designed for complex structural and decorative parts in the automotive and sports sectors.
Hybrid flax/carbon spread tow fabrics are also possible. This is being tested by manufacturers in the snow and water sports sectors.
The CARBIO project is part-funded by Innovate UK and the partners are Composites Evolution, SHD Composite Materials, KS Composites, Delta Motorsport, Jaguar Land Rover and Cranfield University.