The JEC 2015 Jury Prize was awarded in Paris to Hyundai and chassis design partner Axon Automotive (part of Far-UK Ltd.) for the Intrado hydrogen powered crossover car. Two advanced composites materials developed by Scott Bader are used to manufacture the super-lightweight carbon fibre-reinforced plastic (CFRP) car chassis. The vacuum infused chassis components for this new Intrado concept vehicle use Axon Automotive’s highly innovative Axontex TM structural beam technology, which has Crestapol® 1250LV as the specified high performance acrylic thermoset resin.
All of the chassis and frame CFRP components are robotically bonded together by Axon using Crestabond® M1-20 primer-less structural adhesive, with no mechanical fixings needed. The result is an automotive chassis with the strength and stiffness of a similar steel structure, but with a 70% saving in the overall chassis weight.
This latest JEC prize is not the first for Axon Automotive and Scott Bader for this advanced technology. Back in 2012, Axon received a JEC Automotive Innovation European Composites Award for its “B” size city concept car with its Axontex composite frame weighing just 50kg. Scott Bader also received a JEC Partnership award as Axon’s high performance resin supplier, which is still the case in 2015.
Patented CFRP Technology
The internationally patented Axontex structural beam technology has a 3D woven structure, comprising a carbon fibre braid over machine laid multiple preforms made of closed cell low density polyethylene (LDPE) foam. Crestapol 1250LV resin is then infused by vacuum assisted resin transfer moulding (VARTM) around the carbon fibres and LDPE preforms; the carbon fibre specified is Hyosung’s Tansome®
The combination of the superior mechanical properties of Crestapol 1250LV resin with the Axontex technology’s internal web configuration produces moulded CFRP chassis parts which are very light weight, yet provide the very high stiffness and mechanical strength properties needed for this type of vehicle; an ultimate tensile strength (UTS) of 900-1000 MPa (to BS 2282 Part 4) combined with a heat deflection temperature (HDT) of over 130oC have been consistently recorded during extensive testing of this composite system. A specific automotive related test is the seat belt load test according to ECE regulation 14, which the Axontex system passes, resisting up to 1350 daN +/- 20 daN per attachment.
First unveiled in 2014 at the Geneva Motor Show, the Intrado car is still at the concept stage and so the chassis is manufactured for Hyundai in the UK by Axon Automotive Ltd. at its factory in Northamptonshire, where it moulds and assembles the CFRP chassis to Hyundai agreed specifications. For more than two years, the Axon team has worked in close collaboration with Hyundai’s European Technical Centre, Scott Bader’s technical teams, and the two key carbon fibre supplier partners, Hyosung Corporation and Lotte Chemicals, to develop the exact design specifications needed for the chassis and frame of this crossover vehicle.
A key objective set by Hyundai was to achieve the lightest weight possible for the final assembled chassis and frame of the Intrado to maximize the range and performance of this, zero emissions, hydrogen powered vehicle. Dr Kevin Lindsey, Technical Director for Axon Automotive and Far-UK, commented “Significant additional weight savings were achieved in the final assembled chassis by being able to bond all the sections together. The Crestabond structural adhesive has an ideal combination of high load bearing adhesion strength, with flexibility, toughness and high impact resistance, even at low ambient temperatures.”
Robotic Adhesive Application
To assemble the CFRP chassis, including bonding in a number of steel and aluminium brackets, required the Crestabond adhesive to be precisely applied by Axon using an in-house robotic system in combination with a bulk dispenser and pneumatic gun; Axon has found that using a robotic application system for the adhesive consistently provides the level of quality needed, with precise control of the application, as well as being more cost effective. Using this approach provides OEMs with acceptable levels of productivity for medium to high volume automotive production.
For automotive engineers, the Axontex CFRP beam system offers enormous design flexibility, since it is suitable for manufacturing both straight and curved structural and load bearing parts, with no size restrictions. This innovative carbon fibre composite system provides lightweight parts with exceptional strength and torsional stiffness, plus a high resistance to deformation and bucking. The Axontex system is ideally suited for a vehicle frame, which needs both rigidity and high impact crash resistance performance. Another significant road safety structural test this system has undergone is the specific energy absorption (SEA) test; SEA is a measure of the ability of a material to absorb energy from a cash impact loading. The Axontex composite system can provide up to 1.5 times the SEA of aircraft grade aluminium.
High Performance Rapid Cure Resin
Crestapol 1250LV is an ambient temperature curing urethane acrylate based thermosetting resin, which is compatible with carbon fibres. It was developed by Scott Bader specifically for producing high performance carbon fibre reinforced (CFRP) and glass fibre (GRP) parts by vacuum infusion, resin transfer moulding (RTM) or any closed mould process. Crestapol 1250LV provides a cost effective alternative to epoxy infusion resin systems. Most composite parts made from Crestapol 1250LV are used in service after manufacture at ambient temperature without needing any post curing. However, to achieve even higher levels of temperature and mechanical performance that may be required by a specific end application, various post cure regimes can be utilised. Scott Bader has several Crestapol closed mould and pultrusion application projects ongoing around the world in a number of high performance markets including: automotive, marine, building & construction, rail, and oil & gas extraction.
Further details about Scott Bader and the complete range of resins, gelcoat and structural adhesive products available for composites, visit www.scottbader.com.
To find out more about Axon Automotive Ltd. and its Axontex technology, and Far UK Ltd., visit www.axonautomotive.com and www.far-uk.com.