The right train of thought

Composites in Manufacturing hears about the BRAINSTORM project, a partnership that has created a new design of incredibly lightweight Very Light Rail vehicle frames that are weaved, or braided into a series of tubes to create a prototype demonstrator frame.

Driven by the rail industry's challenges to industry and academia known as the 4Cs - reduce Cost and Carbon emissions and improve Capacity and Customer satisfaction - project BRAINSTORM aimed to develop and demonstrate the applicability of braided composite structures to a novel, lightweight, modular railcar solution.

The BRAINSTORM project ran from early 2018 to mid-2019 and was underpinned by the expertise and collaboration of leading UK innovators at FAR Composites, Composite Braiding Limited (CBL), Transport Design International (TDI) and the Warwick Manufacturing Group (WMG).

With extensive expertise and knowledge in rail, automotive, bus and aerospace, project partners TDI, Far UK, CBL and WMG provided a radical approach to rail vehicle lightweighting, as well as identifying significant opportunities for exploitation and creation of a UK-centric supply chain in this industry. This cross-sector project team designed, developed and manufactured a prototype spaceframe as a lightweight structural solution for Very Light Rail (VLR) application.

The consortium pioneered new ways of deploying technology, materials and processes to produce the vehicle frame using connecting tubes weaved from carbon fibre composites. The solution was successful in demonstrating reduced weight whilst maintaining structural integrity and affordability.

BRAINSTORM - ‘BRAIded Novel beam STructures with Opportunities in Railcar Manufacture’ – was funded by the Department for Transport (DfT) and supported by Innovate UK (IUK) as part of the Innovation in Rail 4 programme.

The project received national recognition following a visit to WMG by Secretary of State for Business and Industry, Andrew Stephenson and will be showcased at Advanced Engineering 2019 in October.

Meeting the challenge

Light rail manufacturers strive to reduce weight and find lighter materials to replace steel or aluminium components in order to make VLR stock more economical to run and reduce carbon emissions, rail wear and maintenance downtime. Advanced composite materials, whilst lighter and very proficient, have historically been regarded as an expensive solution, only capable of low- to mid-production volumes. The required strength of rail components and compliance with safety regulations also meant they have had limited use in traditional rail construction.

New opportunities are now emerging with the development of ultra-light rail transport networks but solutions need to be resilient for a long life in service, easily repairable and offer enough strength to protect passengers on board in the event of an accident.

The Coventry Very Light Rail project wanted to explore the development and application of advanced composite technology to reduce production costs. Trams typically cost more than £80 million per kilometre and its ambition was to reduce this to less than £10m per kilometre.

With a shared vision and the combined capabilities, knowledge and expertise of the BRAINSTORM consortium, the project team set out to determine if - and how - they could: 1) Design and make a light rail-related structural component, and 2) Demonstrate the potential benefits to the light and urban rail sector of composite components.

Shared vision for innovation

As lighter materials tend not to be as tough as steel or aluminium, they cannot simply be employed as a direct replacement for these metals in light rail manufacturing. The BRAINSTORM consortium therefore had to consider which components of the infrastructure were suitable and safe to have weight removed and where a composite solution might be proposed as a viable alternative. Discussions and ideas ranged from basic, functional solutions such as handrails to more structural and complex VLR carriage components.

The team had a shared vision for using the Innovation in Rail support and DfT funding to demonstrate a unique innovation and provide a solution that had ‘real world’ potential for development and deployment.

They decided to design and make a tubular ‘spaceframe’ chassis – providing the body shell and required mechanical performance for VLR carriages – and agreed that, whilst ambitious, this was possible within the available timeframe.

As the consortium had considerable collective experience of metallic equivalents and their application, the team were in a good position to understand the assurances and outcomes required by commercial customers, including the appropriate compliance with industry regulations.

Consortium partners, Composite Braiding and Far Composites are able to design, develop and produce higher volume, lower cost composite components based around braided thermoplastic technologies.

This braiding process creates ‘sock-like’ preforms using highly automated manufacturing techniques. The production methods used significantly reduce both labour costs and waste and can achieve out-turn rates of more than a mile of braided material per day.

The braiding process had already been developed to meet the cost and specification needs of the automotive industry. Based on this experience, the team estimated that - in full-scale production for VLR use – the whole moulding cycle could be reduced to less than five minutes, demonstrating the potential of this cost-effective process for high-volume applications. This predicted efficiency has the potential to remove significant cost from the future production of VLR components and structures.

The consortium identified carbon fibre combined with a thermoplastic matrix as the appropriate material solution as this synthesis provides the required strength and both the material and composite components can be processed very quickly.

The connecting beams of the spaceframe were designed with a consistent external diameter but with tailored wall thickness to give optimum cost/weight and structural performance balance depending on where they are used within the spaceframe. This also helped to keep tooling costs down and allowed all joining (assembly by welding and adhesive bonding) to be standardised.

The prototype spaceframe is considerably lighter than its traditional metallic equivalent. It can therefore be lifted easily by hand as part of a VLR assembly process. The efficiency of the production process ensures manufacturing costs are competitive with traditional methods. Additional advantages of the modular, connecting tube solution are that if any individual beam is compromised through accidental impact the damaged section can simply be replaced with a new one.

Rail industry gamechanger

Using advanced lightweight materials combined with rapid processing thermoplastics, the inherently recyclable result is a potential game changer for the light rail industry.

The 15-month BRAINSTORM project achieved the design of a light rail carriage in a braided composite tubular space frame configuration with a full review of the relevant regulatory requirements. In addition, finite element analysis shows that the structure would meet the structural and regulatory requirements (also assessed relative to its metallic counterparts). The manufacture and assembly of a full-size prototype of the front-end structure was on display at WMG and recently won Technical Innovation of the Year at the Global Light Rail Awards in London.

“The BRAINSTORM Project feels like a real step forward to the team at Far Composites,” concludes Far Composites’ director, Lyndon Sanders. “Being able to tap into the industry experience of TDI to hone the principle of a new type of body structure for mass transit applications has given us a fantastic opportunity to develop our offer.

“The collaborative working with Composites Braiding, TDI and WMG to turn that thinking into a physical demonstrator to show what it would be like in practice was really powerful. Now it’s more than a good idea, now it’s an eye-opener for industry players who can see it, touch it and even pick it up.”

www.far-uk.com