A strand of human hair is about 50 micrometres thick. Now imagine splitting that hair into six parts. Carbon fibre is about as thick as one of these parts, ranging between five and nine micrometres. The fibres are obtained from materials containing carbon and they conduct heat and electricity. A division of ELG, ELG Carbon Fibre Ltd. (ECF), reclaims carbon fibres from production waste and end-of-life waste at its Coseley site, near Birmingham (UK). Embedded in synthetic resin, these fibres converted into new products create a composite material that offers potential especially in the field of transportation.
Light on the rails
The French transport group Alstom has also recognised this potential. In joint discussions with ECF, the two companies developed the idea of a bogie frame made of carbon fibres. A bogie frame carries the wheel sets – i.e. the wheels, wheel bearings and wheel set axles – of a rail vehicle such as a passenger or freight carriage. Carbon fibre would offer a whole range of benefits here because bogie frames are usually made from heavy steel components. A carbon bogie frame, however, would weigh only around half as much, making the carriage much lighter on the rails. This, in turn, would mean reduced energy consumption for the drivetrain, reduced rail wear and maintenance costs and, ultimately, reduced operating costs for rail transport. But savings could also be achieved much earlier in the (mass) production of carbon frames, which would not only be cheaper than the steel version but also conserve resources, in turn reducing the environmental impact.
So that’s the theory – what about the reality? While ECF has since April 2017 been setting up the supply chain for carbon fibres with Magma Structures, Alstom has brought scientific partners on board. The Sensors and Composites Group at the University of Birmingham, for example, installed optical strain and temperature sensors in the frame to monitor its condition and wear at all times. In spring of 2018, the project received £1.25 million (almost €1.4 million) from the British Rail Safety and Standards Board (RSSB) in a vehicle dynamics competition. This money ensured the design and manufacture of a prototype. The project then received further support with the JEC Innovation Award in the Rail category.
Ahead of the standard
Initial prototype tests began this month in the HAROLD laboratory at the University of Huddersfield, specially designed for testing rail vehicle technology. The laboratory device will test the static and dynamic load capacity of the bogie frame at speeds of up to 200 km/h and with a weight of 25 tonnes on the main axle. Its technical lifetime will be determined during a fatigue test with 10 million load cycles. ECF employees are currently anticipating a test phase of six to eight weeks. The results will then be evaluated and applied to the design of the frame.
To be approved for use on the railways so that it can soon transport people and goods, the frame must comply with the applicable standard at the end of the design process. “The current standard (EN 13749) has been designed for a steel frame, but we want to prove that a composite frame is able to withstand the same loads,” says ECF’s product development engineer Camille Seurat. In the future, the technology behind this could also be applied to other areas of transport, such as car bodies. Talks with customers in Europe and Asia are already in full swing.