Page 5 - Research and innovation un materials applied to railways

vibrations. For this reason and because of their behaviour when faced with fire and smoke,
they are good candidates for applications in structural panels and interiors, floors and the
walls of cabins and coaches.

Composite materials of polymer matrix require special attention due to the challenges and
implications associated with the process of design and manufacture. These types of
materials are usually employed in interior applications and secondary structures. The
natural evolution is its utilization in the primary structure of coaches and in other
important structural components, following the line of development marked by
aeronautics and, more recently, automotion. Railways should draw on the experience from
these sectors and find the most suitable approach in relation to cost structures and
production. The costs of production make it unfeasible to use the processes of
consolidation and curing of pre-pregs in autoclave such as in aeronautics, while the size of
components complicate the adaptation to the process of very high pressure infusion used,
for example by BMW in their models i3 and i8. In Spain there is already experience in the
manufacture of structural components with appropriate properties through liquid
infusion processes, vacuum-bag and out of autoclave curing. It is within this framework
that a number of activities are planned at a European level, with active Spanish
participation, at the heart of the Shift2Rail initiative.

The use of these technologies also requires the development of fiber processing
technologies that automate the process of preparation and consolidation for the dry-fiber
preforms. These automated processes can achieve properties adapted to areas of greater
requirements or local reinforcement, through a mix of different fibers or fabrics or the
improved laminates out-of-plane behaviour, through stitching techniques that add fibers
in the thickness direction or even 3D preforms that can reach almost isotropic properties.

Some of the most common options for raw material are matrices based on epoxy or
phenolic formulations, and their main limitation are the requirements against fire and
smoke, which poses the need to turn to fire-resistant resins, modified with additives. With
regards to reinforcement fibers, aramid, glass and carbon can be considered, the latter of
which having greatest properties.

In the process of design and manufacture of the structural components of new materials it
should be taken into account that, in addition to the challenges inherent in the
development of these materials, as yet no regulations exist. Different companies and
Spanish technology stakeholders are involved in the development of a regulatory
framework, as demonstrated through participation in the European Commission
REFRESCO project, whose objectives are aligned in this direction.

Furthermore, one of the keys of R&D&I is the multi-material concept, with designs which
include the use of more traditional materials such as iron alloys, or aluminum, together
with new contributions made by the metal matrix composites (MMC), metallic foams or
polymer matrix composites. At the same time, these concepts introduce the need to find a
solution to bonding dissimilar materials whilst maintaining the required properties in
terms of static and dynamic loads, fatigue or aging and durability.

The Spanish contribution towards developing specific solutions for the high-speed
Medina-Mecca line is well known. One of the specific issues is the presence of abrasive
particles suspended in the air due to the track running through the Arabian Desert, which
has led to the need for a much higher resistance against abrasion. In this context, solutions
have been sought in the form of materials based on improved resins and paint coats, its

Position Paper: Research and innovation in materials applied to railways 4