Harnessing the benefits
Justin Cunningham discovers the potential of embedding wires within composit
While the concept of embedding wires inside composite structures is still relatively new, it has become the norm for BERU f1systems. Commercialisation of this technological breakthrough is helping the Norfolk based company enter new profitable market sectors.
The most obvious sectors to which F1 and motorsport technology can be transferred are high end automotive and aerospace applications, as these have a similar market in terms of volume and cost. And this is true for Beru f1systems. The company has been working with major automotive OEMs and with major aircraft manufacturers and turbine engine developers, exploring how to embed wiring harnesses within the structures of aircraft, engines and UAVs.
BERU f1systems has built its reputation on supplying the wiring harnesses to almost all the F1 teams. It recognised that composites lend themselves to embedded wiring and set about developing the technology. In the first generation of the technique, wires were placed in the middle of the composite during lay up. PTFE and braided wire harnesses were used to insulate the cables as they would not be affected by the high temperatures experienced inside an autoclave during curing.
However, the second generation approach sees electronic circuits printed on a flexible printed circuit boards, which are again put in the middle of the composite during lay up. As aircraft and indeed turbine engine structures move increasingly to composites, it is another key step to removing weight from the structure.
The company has also developed an embedded wiring harness for Jaguar's C-XF. John Bailey, managing director at BERU f1systems, says: "Once we demonstrated to the design engineers at Jaguar what you can do with an engine wiring harness – embedding everything into the carbon fibre – the penny dropped.
It means the wiring harness can be made to virtually any shape, it makes packaging much similar and actually adds a lot in terms of aesthetics to the design."
The downside of embedding wire in a carbon fibre structure is you cannot get to the cables to alter the wiring. However, this does make the cabling effectively tamper proof and has been dubbed 'fit and forget' by the company. The cables have a number of redundancy features built in and proliferations for additional systems, so wires can be attached for future alterations.
Automotive OEMs are increasingly looking at composites. Combustion engines are reaching near optimal performance and any future efficiency gains are likely to be small. To get any significant improvement in fuel consumption, the chassis and structure need to be made lighter. But, the minimum requirements for crash and safety systems in modern cars mean advanced materials are likely to play an ever increasing role.
The most significant issue with this philosophy is manufacturability. However, a significant amount of time and money is being spent on research and development, with major industry and government led projects set to address the problem.
Out-of-autoclave curing techniques are already beginning to come to fruition. "However," says Bailey, "while non-structural parts show potential for being produced out of the autoclave, it is highly likely that structural parts will be cured in autoclaves for sometime to come."
Another pertinent issue is the End of Life Vehicles (ELV) Regulations, which stipulate that 85% of a vehicle by weight must be recycled. Composites are generally very difficult to recycle, with the only methods for their disposal being breaking the material up and using it as road aggregate, or using a time consuming and energy intensive chemical process to separate the fibres from the resin.
However, Bailey suggests that if a chassis is made from composite, it could be restored and kept: the idea would be to just change the panels. If the car industry moved to a standardised chassis – say 10 or 20 variants – these could be recycled by the OEM, who could restore and reuse them.
Simulation and finite element analysis work by BERU f1systems will play an important part in the wider implementation of composite technology. Bailey says the accuracy with which his team can now predict composite behaviour is 'scary'. He said that, in advance of an impact simulation, the team will be able to predict accurately the material's behaviour; almost down to the point of knowing how big the shards of material will be and the direction in which they will head. But, he said, much of this skill is down to the individuals entering the data.
The potential of embedding wires within composites has also led the team to look at embedding sensors and heath monitoring equipment inside the structure. At present, this is restricted to F1 teams, but it is a technology that would transfer quickly to the aerospace industry, with the possibility of using composite materials in larger infrastructures such as wind turbines. The ability to monitor the state of the material constantly for internal cracks or delamination, normally hidden from view, would revolutionise any maintenance requirement.
Today, composite structures have to be tested by ultrasound in a laborious process that requires significant time to perform. "While aircraft are on the ground, they are not making money," Bailey concludes, "so minimising the need to check for structural damage or delaminating would be of great benefit to the aerospace industry."
Technology takes tyres internal temperature
BERU f1systems has also been developing wireless technology for use on tyre sensors. "The 'Holy Grail', particularly for motorsport, is to know the temperature of the tyre carcass," says John Bailey, managing director.
Infrared sensors had been used to measure the outside of the tyre, but this only gave surface readings, not what was actually happening in the tyre structure.
"We have developed an infrared system that fits wirelessly into the tyre and that provides a raft of information, combining carcass temperature with accurate pressure data," he says. "A leading tyre OEM is using it for testing and has discovered things about the tyre and its performance that they previously did not know. There is much less packaging and no cabling for these sensors, so you can put them where you want. It could be used for accurate temperature measurement in a restricted or harsh environment."
The company has also developed a key fob for use with luxury cars. Effectively, the cars will be fitted with the same sensor as that developed for F1, allowing the driver to read individual tyre pressures by walking round the car and pointing the fob at each wheel.
As Bailey says: "This avoids you having to go round the car with an air hose at a garage. It is a cool technology that adds differentiation to premier brands."
The company is also applying tyre pressure monitoring for use with bus and truck tyres and is investigating aircraft and off-highway derivatives.
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