Composite materials for the automotive sector - who needs who more?
Nov 24, 2017 Dr Richard Collins
Every year, the conversation at all the big trade shows is the same: This year will be the "big year" for composite material in the automotive sector. This stepwise change is still yet to occur and many question whether it will ever happen, but the evidence is that orders and volumes are gradually increasing and that this field is growing.
The main hype surrounding composites in the automotive sector is to do with their strength-to-weight ratio. Legislation and competition will keep the spotlight on this area; a 10% weight reduction can give a 7% efficiency improvement, which can be translated directly into fuel or range efficiency.
Composites are not the only solution for the automotive sector and they do not come without their downsides, as was discussed in a previous article. Lightweight metals and their alloys or improved high-strength steels are the most promising frontrunners. Aside from competitive weight savings, advanced metals also come with added advantages in the familiarity with which they are handled and repaired and the end-of-life opportunities, which are highly relevant as these industries aim towards a circular economy.
Composites have, of course, been used for sportscars and motorsport for a long time, and the percentage used in premium vehicles is forecasted to increase within the near-future. BMW have been the only OEM to embrace carbon fibre reinforced polymer (CFRP) for high-volume low-cost vehicles, but there is plenty of movement elsewhere as nearly every automotive OEM holds partnerships or has carried out collaborative projects with one of the big carbon fibre providers.
IDTechEx forecast that this modest growth for composite fibre in the automotive sector will have a 10-year CAGR of 6.5%. This growth will be spread across the different roles composites can play within this sector to differing degrees, and this article will consider the main opportunities.
IDTechEx have been extensively analysing this field and a complete insight into this industry can be seen in the report Composites 2017-2027: Innovations, Opportunities, Market Forecasts.
Where will composite parts get used in traditional vehicles?
The attention is always about CFRP parts in structural bodywork, but the many downsides have stopped this from emerging onto the scene for high-volume vehicles. IDTechEx predict that multi-material solutions will be the likely solution and some manufacturers are already looking to make hybrid parts, the expensive CFRP can be used to provide the high stiffness only where required.
A notable uptake has been seen for the use of glass fibres embedded in thermoplastic resins for both interior and exterior parts. Glass fibres keep the cost down dramatically, which is important for high-volume vehicles that will only be turning relatively small profit per car, and thermoplastics are quick and easy to use in compression molding equipment. All the big thermoplastic players are getting progressively more involved with this scene including Lanxess, DuPont, DSM, Sabic, and more. New products and applications are being regularly announced and the significant innovations are highlighted and profiled in IDTechEx Research's report Composites 2017-2027: Innovations, Opportunities, Market Forecasts. A few are included in the images below, including: a GFRP oil pan from DuPont in collaboration with JLR (left), GFRP suspension spring from Hexion (centre left), GFRP pedal from Lanxess (centre right), and CFRP wheel from Carbotech (right).
Source: IDTechEx and Hexion
Outside of the body of the car, a key potential area for composites are the wheels. Wheels have high structural requirements, a large fixed weight, and an added negative impact due to the rotational mass, this is even more relevant for the large wheels of HGVs. There are several specific examples that at present are limited to very high-end cars, but this is anticipated to emerge into HGVs and higher-volume cars in the near-future.
Natural fibres are also on the rise in this area. Bast varieties (including flax, hemp, and jute) are gaining increased prominence, not only for their beneficial properties, but also the increased pressure for life cycle assessment considerations in this sector. One of the major questions here is whether supply can be grown at a rate to keep up with demand.
Are we moving away from a monocoque design?
The automotive sector is a very conservative one, and changes do not come easily. The classic high-volume car is a monocoque structure, this is where the bodywork is structurally integral to the design, but there are an increasing number of innovations outside of this where high-performance composite materials could play a very large role.
Far-UK have used their braided carbon fibre material, called Axontex, to develop cost effective spaceframes. Spaceframes are where a framework provides all the load bearing requirements and the exterior panels are non-structural. They believe a volume car will be made using this technology by mid-2018.
The iStream, from Gordon Murray Design, is another rethink from traditional vehicle, where composite sandwich panels are bonded to steel tubing with a substantial weight reduction. This design will be used by Yamaha's entry into the automotive world with their Motiv city car due 2019.
Westfield with Axontex spaceframe (left) and iStream with composite panels (right).
Source: IDTechEx and Gordon Murray Design
How do electric vehicles differ?
IDTechEx predict that we are near the tipping point for electric vehicles (see article). EVs provide an opportunity for composites that has yet to be even slightly exploited.
Firstly, as before, there is the opportunity for a structural rethink when considering where the battery is positioned allowing for whole new designs, but if we just consider the more conventional battery layout there is still lots of scope.
Batteries do not have the same temperature expectations of a traditional ICE, but box and tray manufacturers must consider additional factors including both galvanic corrosion and how they should ideally be non-conductive to protect occupants and first responders in an accident scenario.
A prime example comes from the VW e-Golf that will be launched in 2018 (see image below). The battery tray will be made of glass fibres embedded in polypropylene, materials that cannot go anywhere near a traditional engine. It can be manufactured in 1 minute and is 35% lighter and 30% cheaper than its aluminium counterpart. This shows the larger scope composites can have in an EV driven world.
Battery tray for the VW e-Golf (left - source: IDTechEx photograph) and battery box for the Chevrolet Spark (right - source: CompositesWorld.com)
Would the composite industry dramatically suffer with a minimal growth rate for the automotive sector?
Although the conversation is regularly orientated around the automotive sector, it is a long way from being do-or-die for the composite industry. It would undoubtedly be a big pay-day for the suppliers if a stepwise change were to happen, but the next-step is likely to be a multi-material set-up and small volume increase. Unlike a few decades ago, composite materials are on the agenda on all automotive manufacturers, but intelligent design strategies and small margins will mean it is only used in specified amounts. Nevertheless, there are still plenty of profitable industries that they are diversifying into.
For CFRP, this growth is into the energy sector as spars for wind turbines, CNG fuel tanks and rail transportation. Capacity expansion plans are being announced and IDTechEx forecast that there will be a significant CAGR of 8.6% for the next 10-year period. A previous article highlighted the wealth of opportunities within this industry.
As for the automotive sector, there will remain a need to lose weight across their fleets, but as to whether this is ultimately the right solution the jury is still out.
For full company profiles, complete industry analysis, and a key insight into the innovations and opportunities within the composite industry visit www.idtechex.com\composites.