London Underground opens door to Stephenson Award

A London Underground project supported by the NCC has won the prestigious Stephenson Award. The winning door was the result of a TSB- funded project under the “Accelerating Innovation in Rail” funding call. A consortium, led by Transport for London (TfL), embarked on a project to replace the door on the existing Central line tubes with a light weight thermoplastic door. The consortium included Transport for London, Atkins, Wabtec, UCL and the National Composites Centre. The project included the selection and testing of an appropriate composite material that could withstand the most stringent of fire regulations imposed in the underground environment. The current metallic door structure also required a trip back to the drawing board for re-modelling using finite element analysis (FEA). The novel thermoplastic door, manufactured at the NCC, was tested to validate the FEA model, and then tested to the exacting fire and mechanical performance standards required by TfL.

Jeff Ive; Liquid Resin Moulding & High Value Manufacturing Engineering Capability Lead explained,
 “This project has taken full advantage of the NCC remit to cross pollinate technologies from different sectors. Using materials used in an Aerospace application and processing them in a novel manner, we have been able to deliver an end product that has the potential to improve public transport for generations to come. We have drawn on the experience and insight of engineers, technicians and supply chains across numerous sectors to deliver this challenging project. It is a pleasure to receive acknowledgement from the rail industry, and we look forward to working more closely with them in future. There is a great opportunity, due to the door’s potential recyclability, to advance environmental materials solutions in the sector.”

The understandably stringent fire and toxicity regulations that are imposed on underground civil transport give this project its real challenge. Composites, in particular thermoset phenolic resins, have established and well-documented uses for underground civil engineering applications. However, while meeting FST requirements, these materials have inherent issues with durability as the resins cure in a brittle manner. Phenolic resins are also used within the aerospace industry, so the consortium assembled for this project sought to explore the use of fire retardant thermoplastic laminates also currently used for simple aerospace applications within the interiors of aircraft. A thermoplastic solution was seen as desirable as they are thermoformed and potentially both more durable, and recyclable.

The high performance thermoplastic laminate chosen had a high processing temperature and the pre-consolidated nature of the material posed problems in production that NCC had to overcome. Ordinarily a hot pressing process would be preferred to cope with the complex geometry of the parts. The large press capability within the NCC is currently being upgraded, so the smaller parts were processed using the existing press capability with great success, and the larger parts were consolidated in the autoclave as seen below.

This approach established the precise processing parameters required for the thermoplastic pre-preg material and allowed a prototype to be built and tested. The NCC is extremely excited to have developed this capability and understanding, as it led to knowledge and experience important to the NCC at a time of acquisition and commissioning of the new press capability.

The project has also received other acknowledgement of its achievements, winning a Rail Industry Innovation Award (RIIA) in the Environmental category, much to the delight of the technical lead on the project, Jeff Ive. Jeff, one of the many talented engineers at the NCC added, “I was thrilled to see the NCC obtaining recognition for its capability to tackle complex prototyping projects, and pleased that a wider audience could appreciate the manufacturing capability of the centre.” 

Paul Gallen from the NCC Business Development team, who attended the RIIA award ceremony, was pleased to have this platform to engage with the most innovative organisations within the sector and said “Composite materials potentially offer advantages to many rail sectors, in infrastructure as well as rolling stock. The through-life cost reduction that composites bring to installation and maintenance can often only be fully realised through new design solutions, reducing part count, and new supply chain models. The NCC is actively engaging with all major stakeholders in the sector to identify these opportunities and help knock down barriers to implementation.”

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