The aerospace and defense sectors have already greatly benefited from lightweight advanced composites which have aided in major performance improvements. As these benefits are long-term, leading manufacturers, such as Boeing and Airbus, are now building structural parts using over 50% advanced composites for their aircraft, such as the B787 Dreamliner and A380.
The composite structure designed specifically for commercial aircraft has a honeycomb prepreg composite laminate that was created in an autoclave. This material can be used in exterior applications, such as flaps, access panels, doors, wing sections, antenna radomes, and ailerons. It can also be applied for interior applications, such as floor panels, galleys, toilets, partition walls, ceiling panels, and sidewalls.
The railway sector is now also looking towards applying advanced composite materials.
TRB Lightweight Structures have prepared themselves to meet the demand for composite materials by increasing their number of composites design and manufacturing units, obtaining certifications, and employing additional labor (Figure 1). The company now has the capability to assist in training manufacturers to leverage the key performance benefits offered by advanced composites.
Figure 1. New vacuum molding equipment and experienced composites technical staff have been added to the business
Novel Capabilities of TRB
TRB has been involved in assisting train manufacturers and operators for many years. It is an IRIS-approved, Tier 1 supplier of lightweight engineering solutions for train manufacturers across the globe. It has been involved in designing, manufacturing and even installing parts for well-known projects, such as the London Victoria Line, the UK West Coast Main Line, and Hitachi’s new high-speed train.
The company offers numerous interior and exterior parts, such as galleys, storage units, floors, partitions, and main doors and specialty detrainment doors for newly built as well as renovated rolling stock. TRB now has the capability to design and process alternative lightweight composite materials that meet rigorous smoke, fire, and toxicity regulations outlined in EN 45545.
The following are some of the composite materials available from TRB:
- Phenolic sheet molding compounds
- Modified epoxy glass prepreg
- Carbon/phenolic prepreg
- Fire retardant foam cores
TRB’s latest 4,000 square foot clean room (Figure 2) is constructed in compliance with ISO 14644 standards. It also has a newly installed autoclave heated pressure vessel measuring 3 m x 1.5 m.
Figure 2. TRB Lightweight Structures has invested in a purpose-built 4000 sq. ft. clean room, which meets ISO 14644 classification standards for manufacturing composites with AS9100 accreditation.
Autoclaving is a well-recognized manufacturing process used widely for building aerospace-approved parts using only superior quality composite structures. Recently, TRB obtained AS9100 (BS EN 9100) aerospace accreditation. This globally recognized certification is a quality standard for the aerospace and defense sectors. The company already has the International Railway Industry Standard (IRIS) and ISO 9001 certifications.
New rail projects are beginning to benefit from the use of advanced lightweight materials. The Bombardier’s AVENTRA platform weighs only about 30-35 tonnes, a decrease of nearly 28% from earlier units that weighed 42 tonnes. Another huge benefit is that 50% less electricity is consumed by the AVENTRA compared to the Class 319 train. The AVENTRA is also faster, significantly reducing journey times.
Similarly, the Siemens Desiro City platform is a lightweight and energy-efficient modern train. It is on average 25% lighter than existing UK trains, thus consuming much less energy.
TRB is involved in creating lightweight solutions along with its rail customers. Recent composite projects handled by TRB include:
- New lightweight composite antenna cover for Alstom Transport (Figure 3)
- Corrosion damage repair work using a new TRB composite-based patching system for portions of castellated steel roofs on train carriages
- Reverse engineering a stronger yet lighter coupler hatch for the West Coast Pendolino
- In partnership with leading OEMs, cost-effective composite solutions are being designed and constructed to reduce the weight of key parts by as much as 60% in certain cases
Figure 3. A ballistic-strength FRP composite laminate design was chosen for these antenna covers, which are located at the bottom of Alstom train carriages
Reduction of Maintenance Costs
Instead of choosing the traditional welded mild steel patch repairs, Virgin Trains has approved the new train roof composite repair system designed by TRB. The traditional steel patch repairs are prone to corrosion, and therefore require re-repair. Conversely, TRB’s polymeric composite materials have inherent corrosion resistance. This rail maintenance project was the first of its kind in the UK. The composite patched roof section offers the same structural reliability as a welded steel patch.
The composite roof repair sheet material from TRB is manufactured from a glass fiber- reinforced epoxy prepreg resin. The resin is placed in the clean room and then molded at high temperature under pressure in the autoclave, according to the aircraft specification quality regulations. Sheets measuring 1 m2, with a thickness of 0.765 mm, are produced and then cut to the size requirements of the train roof design profile.
An epoxy glass patch is bonded over the damaged section of the roof. The rail-approved structural adhesive used for roof repairs is certified to BS 6853 and BS 476 fire standards. This roof repair format is cost-effective, and requires minimal maintenance due to the long lasting corrosion-free feature. Overall, it prevents the need for a £100,000 entire train roof replacement. Furthermore, the rolling stock is out of service for less time because roof repairs can be done within 24 hours, thanks to easy and rapid application of the TRB composite patch.
TRB has not only invested in major areas to expand its capabilities, but is also implementing continuous improvement programs throughout the business in order to optimize efficiency, increase quality to greater standards, and achieve cost savings. The company has grown by about 10% annually, and has added nearly 4,000 square foot per year of new factory space, for the last four years.
Richard Holland, managing director at TRB, explained the company’s new strategy and business expansion. He said that the company has worked over the last 18 months to put new composite capabilities and innovative business improvements in place. TRB has a long association with the UK rail sector, and will continue to deliver a number of advanced lightweight materials to meet future requirements of the railway sector.
This information has been sourced, reviewed and adapted from materials from Rail Professional, provided by TRB Lightweight Structures Ltd.
For more information on this source, please visit TRB Lightweight Structures Ltd.