Composite nose sections for our TGVs. Plant-fibre fairings1 for our TERs. Metal parts made with additive manufacturing. Paints and coatings that repel viruses and bacteria. Every day, our Mechanical Systems and Interactions (SMI) Group works with people all across SNCF and in academia, exploring new materials to improve both operational performance and passenger satisfaction.
To learn more, we spoke with Sébastien Arrighi, head of the SMI Group, and Benoît Dodin and Tanguy Choupin, project leaders in our Research Division’s Innovative Materials unit.
An ever-changing field
For these specialists, the goal is always the same: bring research and innovation to our trains and infrastructure. “The field of innovative materials and processes changes every day,” says Sébastien Arrighi.
Since trains last for around 40 years, it’s important to use the right materials. But how to choose? “We’re connected to all of the disciplines within SNCF. People come to us for the science and tech expertise they need to address their issues. But we also monitor developments in our field, researching materials, assessing their value for rail, and suggesting trials tailored to SNCF Group’s business units,” explains Benoît Dodin.
Promising leads are tested in programmes that last from 6 months to 5 years, depending on the research required. From bio-based materials and composites to antimicrobial coatings and additive manufacturing, we’re putting these new materials to work in our trains and infrastructure.
Boosting performance with composites
Lighter and more resilient than metal, composites have become essential to the rail industry. “Trains have had trim made from composites since the 1960s, but using them for structural components—the skeleton of the train—is a major breakthrough,” says Tanguy Choupin.
Since February 2021, we’ve been trialling a composite bogie connector in a TER 2N NG train in commercial operation, working with Alstom and CNIM, an equipment manufacturer. The bogie connector links the body of the train—where the passengers are—to the bogie, which is attached to the wheels. In addition to being 43% lighter than metal, composite parts last longer and are more resilient. Trialling this new part in commercial operation is a first for the French rail network.
“On the safety front,” says Tanguy Choupin, “the biggest hurdle was getting it validated by the national Railway Safety Authority (EPSF).” Benoît Dodin adds, “If our composite parts last longer than metal ones, it could mean less maintenance, which could mean lower fares for passengers. That’s the promise of these materials. Now we need to confirm their performance in operation.”
We’re also testing a new composite fairing for our double-decker TGV INOUI and OUIGO trains. Underway since April 2021, the trials are part of our COCA project, aimed at developing a shell with optimum aerodynamics and impact resistance. By changing its shape, our specialists have made the part more aerodynamic and energy-efficient, eliminating a total of 537 tonnes of CO2 a year. That’s a vital concern at SNCF Group, where we're actively committed to the ecological transition in transport. The new composite TGV nose also makes the fairing more resistant to minor impacts, which reduces the number of parts that need replacing. By 2028, it will be installed on 95% of our double-decker TGVs.
Using composite materials for structural components—the skeleton of the train—is a major breakthrough.
Tanguy Choupin, Innovative Materials project leader
Meeting of minds
The COCA project brings together some 30 SNCF experts from 5 different entities: our Engineering Cluster East in Bischheim; our Rolling Stock Engineering Centre (from sites in Le Mans and Rouen Quatre-Mares); our Atlantique Technicentre; our Traction Division; and the Railway Test Agency (AEF). The project is led jointly by the Industrial Operations Division at SNCF Voyages and our Technology, Innovation and Group Projects Division. Preparatory work for the project spanned 2.5 years.
Bio-based materials—replacing glass with plants
Our SMI Group juggles multiple priorities—protecting the environment, controlling costs, delivering high performance and supporting local French suppliers. One way to solve this equation is bio-based components made from natural linen and hemp fibres grown in France. “French growers have supplied materials to industry before—for thermoformed automotive parts, for example—but we’ve never used natural linen and hemp fibres in rail,” says Benoît Dodin.
The aim is to strengthen fairings with plastic parts reinforced with natural fibres instead of the fibreglass-reinforced parts in use today. “These new materials must meet the same safety specifications as fibreglass components,” says Benoît Dodin. In 2022, a prototype will be installed on a TER regional train in Northern France for an 18-month trial. The first of its kind in Europe, the trial is designed to win approval for the new parts and test their technical performance. If deployed, plant-based parts could be 20% more eco-friendly than their fibreglass-reinforced counterparts.
Keeping passengers healthier with antimicrobial materials
At SNCF, we were cleaning and disinfecting trains and stations long before Covid-19. But the pandemic spurred our SMI Group to step up research into antimicrobial materials, says Benoît Dodin. “We and our colleagues in Materials Engineering began to wonder whether there were any materials—coatings, paints, adhesives—that could reduce microbial load. Our aim was to decrease virus and bacteria concentrations on high-touch surfaces on trains and in stations,” such as door handles, grab poles, and vending machine screens. Antimicrobial materials react to germs on contact, and they’re active 24/7. If successful, they could ease the demands on our cleaning and disinfection teams.
“Now we’re thinking about running tests in some passenger operations,” says Benoît Dodin. “I’m working with labs that are developing antimicrobial solutions. If we could deploy them in the future, we’d have surfaces treated with healthy, sustainable materials, and could cut down on chemical disinfectants aboard trains and in stations.
The field of innovative materials and processes changes every day.
Sébastien Arrighi, head of SNCF’s Mechanical Systems and Interactions (SMI) Group.
At SNCF, innovation isn’t limited to new materials—we’re also exploring new ways to make parts. Additive manufacturing, commonly known as 3D printing, is one example. This high-tech process speeds up prototyping and produces customized maintenance equipment—and even replacement parts for our trains. With additive manufacturing, we can cut supply-chain delays and manage our inventory more effectively. As with traditional production methods, safety is our absolute priority. “Whether it’s fire safety standards for plastic polymer parts, or fatigue resistance for structural components made of metal, our safety requirements are ruthless,” says Benoît Dodin.
Additive manufacturing also helps us fight obsolescence. It’s particularly useful as a way to replace 50-year-old parts without having to call in a supplier. One example of microcontacts is decades-old speedometers. “That’s clockmaking, not electronics!” says Benoît Dodin. To replace components and keep these otherwise obsolete systems in working order, we make 3D models and recreate the missing parts at our Industrial Technicentre in Saintes.”
1 Fairings are the contoured exterior shells, or coverings, that give trains their aerodynamic shape and performance.