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Composite rail vehicle bogie shows the future

Rail operators are seeking to deliver a safer more efficient and sustainable rail system, as well as reduce the costs associated with track damage and suspension maintenance.

Recycled carbon composite benefits

Magma Structures has partnered with ELG Carbon Fibre in a consortium of rail industry specialists underwritten by RSSB, focusing on rail carriage bogie weight reduction. Showing the way forward on composite bogie design, this project has won a 2018 JEC World Innovation Award.

Magma reviews the recent technical paper presented by ELG at the JEC event in Chicago on the Future of Composites in Transportation. This shows how ELG recycled carbon fibre, combined with Magma Structures’ manufacturing expertise, can be used to design and manufacture a carbon composite rail vehicle bogie to meet ongoing rail industry challenges.

Global challenges for rail operators

With the price of oil rising, most rail operators seek to reduce fuel consumption on their diesel trains, as well as costs for electric trains where they are usually billed for their daily operations based on traction electricity charges.

Track damage also costs rail operators millions a year in repairs and maintenance.

Charges are levied based on the amount of wear and damage that operator’s trains and carriages cause.

Train weight influences both train fuel consumption and track damage, as well as the lateral forces that carriages incur on steel rails as they go around bends or over track points. As the bogie represents around 37% of the total carriage, reducing the weight of this assembly is vital.

Composites deliver right down the line

The rail industry is increasingly demanding more cost effective and lighter weight structures, in order to deliver rail vehicle design flexibility, reduced installation time and lower maintenance. The industry also needs to reduce many of the costs associated with track damage, and the downtime and financial burden of regularly maintaining train rail vehicle bogies and suspension units. The combination of these requirements make composite material solutions an attractive choice.

“Recycled carbon fibre composites reduce carbon composite manufacturing costs and deliver a light, strong and flexible alternative to traditional metal rail vehicle bogies.”
Camille Seurat, Product Engineer, ELG Carbon Fibre Ltd

A carbon composite bogie is lighter than an equivalent steel or metal alloy frame, can have the mechanical properties of the materials tailored to individual rail vehicle requirements and dimensions, and be developed to accommodate existing bogie ancillary components.

Recycled composites – responsible cost reduction

Corporate social responsibility (CSR) is a key target of most manufacturers around the world that have concerns for the planet’s future welfare. This has resulted in research into ways to get strong, light carbon fibre out of landfill and make it ready for recycling and practical reuse.

Apart from recycling, there are two challenges in the adoption of carbon fibre composites, the difficulty of manufacturing large, complex structural forms, and the cost of carbon fibre itself. Magma and ELG have partnered to provide a solution to both of these critical issues.

The Magma team has extensive experience in manufacturing large composite structures. This includes the design and manufacture of the carbon fibre masts and rigs for the world’s three largest privately owned superyachts, incorporating composite structures over 100m (330ft) tall.

ELG has pioneered the development of recycled carbon fibre, with a unique, high volume process that dramatically reduces the energy requirement for carbon fibre production by 90%.

At its UK facility, the largest carbon fibre recycling plant in the world, ELG is able to process dry, prepreg and laminate carbon fibre in a unique shredding, pyrolysis and chopping process. The mechanical properties of the recycled carbon fibre are measured using single filament testing for classification and quality control purposes.

The company’s revolutionary process means their recycled carbon fibre can be processed and moulded in the same way as virgin carbon fibre and, most importantly, reduces the raw material cost to their customers by 40%.

Progressing the composite bogie project

The bogie has a number of functions that include supporting the car body, guiding the wheelset, maintain rail vehicle stability, transmitting tractive and braking effort and providing a comfortable ride for passengers.

The carbon composite bogie design has to meet all these basic needs and comply with existing UK and European railway standards. Challenging targets were also set by the consortium for the overall composite bogie project:

As there are few existing standards in the rail industry for composite structures, the project will also define new composite standards at a level that can provide the same or better performance versus an equivalent steel fabricated bogie frame.

The bogie design specification is based on an existing class 180 carriage bogie. This has been adapted for composites with a shape that can be manufactured created using a cost effective process, as well as ensuring that the required performance targets can be met.

“A big project challenge has been integrating the existing bogie ancillary fittings, with the same equipment and same relative positions, as well as to meet or exceed any existing performance requirements.”
Damon Roberts, Magma Structures Engineering Director

The main material used in the composite bogie is the ELG Carbiso M nonwoven carbon fibre mat made of 100% recycled carbon fibre. This offers environmental benefits, as well as having 40% lower cost than virgin carbon fibre.

The resin used in the bogie frame has to deliver good mechanical and thermal properties, as well as good water resistance, corrosion resistance and longevity. A key requirement is also fire retardancy to EN 45545.

Once the initial design was developed, it was analysed for likely load cases in line with existing steel rail vehicle bogies.

Throughout the design process cost effective manufacture has been a key consideration for the project.

This includes easy, low cost, consistent and high volume production in the longer term.

Incorporation of a structural health monitoring system was also assessed and determined to be a positive benefit to the design for ongoing structural measurement. This helps to ensure a suitable maintenance program can be established.

Bogie frame testing will include static, tensile, flexural, compression and impact testing following ISO and ASTM composite standards. Cycled load fatigue testing and environmental testing was also undertaken, as well as in-situ process monitoring and structural integrity assessment.

Project milestones to date

Project results and conclusions

Carbon composite bogies can substantially reduce overall costs and maintenance for rail operators through lighter component weight, reduced recycled carbon fibre costs, efficient manufacturing processes, reduced fuel and electric traction cost levies and reduced track wear.

Robust processes developed to use nonwoven recycled carbon fibre in high volume, low cost manufacturing.

The technical and commercial viability of the approach undertaken by the rail consortium has also demonstrated that there are an increasing number of other commercial applications in the wider transportation industry.

About the project partners

Magma Structures is a global leader in carbon composite technology and the design and manufacture of large composite structures. Flexible development and manufacturing processes meet the complex design challenges of clients in the transport, defence and oil and gas sectors.

ELG Carbon Fibre Ltd operates the world’s first and largest carbon fibre recovery plant in Coseley UK, providing high quality large volume recycled carbon fibre to meet the needs of major industrial clients and projects around the globe.

Alstom is a world leader in integrated transport systems, providing equipment, infrastructure, signalling and digital mobility solutions across the transport sector. Alstom offers high-speed trains, metros, tramways and e-buses as well as other types of passenger solutions.

The University of Huddersfield Institute of Railway Research (IRR) is a world leading centre in the field of railway engineering and risk. It helps to improve knowledge on how railway vehicles interact with the track, including suspension performance, wheel-rail contact, traction and braking.

The University of Birmingham School of Material and Metallurgy is a leader in the design and development of in-situ monitoring for railway engineering and the transport systems of the future.

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