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Transportation: Innovative composite designs reduce weight and cost

16.10.2017 15:50 EET



Operators of rail and road transportation are under increasing pressure to reduce energy and fuel consumption and lower total cost of ownership. Composite materials enable new design concepts that weigh less, carry more load, last longer and require less maintenance than metals, without compromising safety. These benefits are already being exploited by market leaders such as MAN, Siemens and Bombardier and will ensure their continued adoption in this competitive market.


Today's rail, coach and bus operators compete in an ever changing and more challenging environment. Environmental legislation calls for improved energy efficiency and fuel economy to conserve resources and lower greenhouse gas emissions and pollution. Passenger numbers are growing, and they demand improved performance, enhanced comfort and more on-board services, without increased fares. Yet efforts to improve the passenger experience often lead to increased vehicle weight and the requirement for greater energy use.

Rail and road freight operators face a similar need to lower fuel usage and emissions, whilst transporting more goods, all at lower cost to customers.

One focus for vehicle manufacturers striving to meet these challenges is lightweighting. By replacing traditional construction materials such as steel and aluminium with lightweight composite materials significant weight reductions can be achieved. This results in improved energy efficiency and fuel economy, or alternatively the ability to carry more load. Composites are also corrosion and impact resistant, leading to reduced maintenance requirements, downtime and expense, and lower life cycle cost. By partnering with Exel Composites, component designs not possible with metals can be realised to satisfy the performance, weight and cost objectives for each individual project. 

The composites advantage

Polymer composites are composed of two main elements: the fibre reinforcement, which determines the mechanical performance of the final part; and the resin, which largely determines properties such as chemical resistance and fire retardancy. A variety of reinforcing fibres and resins can be combined, together with additives, to produce a composite part with the optimum properties for a specific application. Exel has been designing composite solutions to meet the most challenging of industrial applications for more than 50 years. Our expertise encompasses all material combinations, including glass, carbon and natural fibres, and polyester, epoxy and polyurethane resins. The cost-effective, high volume manufacture of structural profiles of consistent quality is guaranteed using our advanced pultrusion and pullwinding technologies, while our continuous lamination process enables the production of thin sheets with excellent mechanical properties. Exel's composite profiles provide numerous unique features that are crucial in the transportation industry.  

High strength with lightweight: Composites deliver strengths comparable to or better than steel and aluminium, but at lighter weight, while their stiffness properties outperform plastics and other non-metallic materials typically used. Lightweight composite components deliver cost savings through easier handling and installation, and lower energy and fuel consumption during use.  

Durability: Composite materials are resistant to a wide range of chemicals, do not rust, and can withstand the harshest weather conditions. Composites also have good impact resistance and can be deformed and spring back to shape without permanent damage. All of these factors lead to low maintenance requirements and a long service life, resulting in through-life cost savings. Many well-designed composite structures are still in use after 50 years of service.

Design freedom: The pultrusion process offers the designer major freedom regarding the geometry, properties and design of the finished profile. Going beyond the design limitations of metals, composites allow complex geometries to be achieved, and it is possible to integrate a number of functions into one component. This parts reduction can deliver lower component cost as well as easier installation. Exel manufactures the largest and most complex profiles on the market. Profiles of any length can be produced, minimising joining requirements, with widths of over 1 m. With composites it is possible to achieve the same strength characteristics as steel with much thinner wall structures, presenting further potential for weight reduction and novel design. Exel's technology enables the thinnest wall profiles available today.

Thermal insulation and dimensional stability: Composites are excellent insulators, minimising heat loss and enabling the design of highly energy efficient systems. A very low thermal expansion results in excellent dimensional stability, and composite materials retain their properties even when exposed to cold temperatures.

Good appearance: Exel's manufacturing processes deliver the best surface quality in the pultrusion industry so that profiles are produced ready for painting or coating. Two-component polyurethane paints give excellent visual results and the painted components can survive the harshest weathering tests.

Easy to bond: Composites are easy to cut and drill. They can be easily adhesively bonded to metal framework. This fast, simple assembly process reduces installation cost, and creates a clean, watertight join.  

Fire safety: Fire safety is critical in the transportation industry and resin systems have been developed to comply with the most stringent fire safety regulations. Exel has certified formulations meeting the challenging performance levels for the new EN 45545 rail standard. 

Sustainability. Composite materials offer a more sustainable alternative to metals. Their durability and resistance to corrosion result in a longer service life, lower maintenance requirements and less frequent replacement. Lightweight composite products are often easily handled and installed without heavy lifting equipment and shipment weights are lower. Direct contributions to environmental impact can be seen in applications that reduce energy requirements. Recycling routes are available for end-of-life pultruded profiles. 

Innovative designs for transportation

Exel Composites has designed innovative composite solutions for the transportation industry for more than 25 years. We have developed hundreds of designs for market leading companies around the world, including MAN, Siemens, EvoBus, Bombardier, VDL, Transtech and Iveco. By partnering with the customer during the product development phase, we can create a design to satisfy the customer's technical and financial targets. We also offer a range of finishing options – from machining and drilling, to coating and painting – to deliver a finished product ready to install. 

In rolling stock composite materials enable significant weight savings, complex shapes in design and low maintenance costs, which all drive lower energy consumption and total costs. Composite materials enable new design concepts. Exterior body panels can be produced at over 1 m wide, with integrated functional elements. These can be adhesively bonded to the steel frame of the train and painted with the rest of the body. Interior components can be re-designed for lower weight and cost. It is possible to achieve an optimum combination of large complex shape with thin enough walls for weight saving, excellent surface quality for an attractive appearance, and the fire performance required for passenger safety. Typical applications include roof systems, which can span the whole ceiling from window to window, and air conditioning ducts and heating channels, where composites reduce energy loss.  

Bus and coach applications for composites include exterior parts such as cant rails and cant rail extensions, skirts, third panels, and luggage door panels. Pultrusion allows the production of large external profiles of a uniform quality and strength and a high quality painted finish can be achieved. Thanks to the high impact resistance of composites surfaces resistant damage and scratching, and excellent corrosion resistance means parts withstand the harshest weather conditions and are unaffected by salt on winter roads. In interiors, pultruded composite parts include coves, heating/air ducts, ceiling profiles, flooring, side walls and panels, and luggage rack components. Multi-functional coves can be designed, incorporating lighting systems and other functions in the same profile, reducing installations costs.  

Composite profiles are also employed in a very wide array of products in trucks and trailers. Large side panels with integrated functions (e.g. click fit joining) deliver installation advantages. Structural elements offer mechanical strength with controlled flexibility. Composite under-run protection bars and interior scuff strips are damage tolerance and corrosion resistant. Streamlined external capping profiles can be designed, improving aerodynamics. Internal trim profiles are not affected by cleaning products. In flooring systems, composite laminates are employed to reinforce wood.

The thermal properties of composites are particularly beneficial in refrigerated truck applications. Body and door framework profiles are lightweight, robust, and increase energy efficiency, preventing condensation and ice formation. In insulated panels for sectional doors composites help maintain the temperature in the refrigeration area and ensuring the cold chain.

Collaboration is key to success

The adoption of composite materials in the transportation market is set to grow as operators continue to be challenged by more stringent demands for energy and fuel efficiency and lower cost of ownership. But to fully exploit their many benefits collaboration with a composites expert from the outset of the project is key to success. As a trusted partner to the transportation industry Exel Composites will continue to develop new materials and pioneer new design concepts in collaboration with our customers to deliver the optimum combination of weight, cost, performance and safety. With global, high volume, production capabilities, we are ready to cater to growing demand for innovative composites solutions for rail and road.

To find out more about Exel Composites' solutions for road and rail applications please contact Eric Moussiaux, Product Business Owner, Transportation.

Exel Composites Oyj, Vantaa head office, Mäkituvantie 5, FI-01510 Vantaa, Finland