Page 4 - Research and innovation In advanced materials with application to the railway sector

II. ROLLING STOCK

The developments in materials for rolling stock must respond to the objective of a more
sustainable, economic, and efficient transport. The contribution to this goal can be classified
in different areas:

NEW ALLOYS

Nowadays, aluminium remains perhaps the reference material in the manufacturing of
railway cars. The success in its introduction and permanence is related to its lightness and
to innovations in manufacturing and welding processes, which made it an extremely
competitive solution. New alloys, perhaps adapted from the aeronautical sector, and
improvements in welding processes, such as FSW (Friction Stir Welding) are innovation
vectors that are still relevant today.

In the new alloys section, the sustained tendency to have steels with better mechanical and
wear behaviour stands out, in general for the manufacturing of rolling stock and with
special intensity, among others, in braking systems.
The development of special alloys is also a challenge in the expansion of additive
manufacturing technologies for lightweight components, with appropriate strength and
fatigue properties. Likewise, metallic foam applications are being developed in structural
systems and components.

COMPOSITE MATERIALS

The incorporation of polymer matrix composite materials is also common in the railway
sector. It is a trend that is well established in the wind sector, in the aeronautical sector and
increasingly in the automotive sector, and which has also subject of work in railway
applications. The working lines in this area focus on the extension of the use of this type of
materials to new components for structural and non-structural applications, on the
introduction of recycled and recyclable materials and on the availability of a greater variety
of fibres, resins and cores that allow adjusting the design to existing needs. Among the
needs, noteworthy are, for example, the requirements related to fire and smoke toxicity, or
the response to the impact of ballast, aspects for which these materials present certain
weakness.

This promotion of the use of composite materials goes through the development of methods
for manufacturing and joining components, in accordance with the economy of scale and
type of parts specific to the railway sector. At this point, the commitment to obtain
components with the appropriate properties through consolidation and curing processes
outside the autoclave stands out. In addition, in order to ensure the quality, repeatability
and stability of the processes, different intelligent manufacturing technologies are
incorporated, the control of processes in real time, and the development of reliable and agile
inspection methods that allow to ensure a correct consolidation of the materials, also of the
joints, especially in components of structural responsibility.

Lagging these innovations in materials for the primary structure, rolling systems, especially
critical in terms of responsibility, also require the development of new material
formulations. These systems also seek to have solutions with high damping capacity,
elastomeric materials, and new elastomer-metal interface designs.
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Position paper: Research and innovation in advanced materials with application to the railway sector
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