A US joint venture has come up with an aluminium composite brake rotor concept it claims will weigh in as much as 60 per cent lighter than its conventional cast iron equivalent, and last up to three times as long.
Jointly developed by metal matrix composite (MMC) specialist REL and a research team from New York University’s Polytechnic Institute, the prototype under development, dubbed a ‘one-piece functionally graded hybrid (fibre/particle) reinforced aluminium alloy matrix automobile brake rotor’, has the potential to carve up to 15kg off the weight of cars using conventional disc brakes. That’s significant for car makers facing increasingly stringent fleet fuel economy requirements. Current US law is pushing the industry towards a fleet average of 54.5mpg – that’s 4.3L/100km in our language – by 2025.
Composite brakes aren’t new, but nor are they cheap, meaning to date they have been reserved for motorcycles, track cars and high-performance sports cars.
In its early phases, the project will ‘explore the concept of a one-piece, hybrid reinforced rotor’, REL and NYU-Poly stated in their pitch for a small business innovation research grant from the National Science Foundation. The $150,000 grant has helped in the initial product design, material and manufacturing process for the prototype.
The pitch claims the new rotor will have ‘significantly better properties and lifespan compared to conventional materials due to the functional reinforcement gradient (FRG) across the braking surface and the tailored macro-interfaces’.
Conventional mainstream brake rotors are made of cast iron, which is durable but heavy. Iron also doesn’t adapt well to the demands placed on the three functional zones of the rotor, each of which requires different strain and thermal characteristics to work at its best. The prototype study will focus on optimising performance in each zone, it continues: ‘a) friction interface (heating zone), b) venting (cooling zone) and c) mounting hub (torque transfer zone). Each of these zones must have specific material attributes for the rotor to function properly.’
The prototype will see traditional rotor materials replaced with a purpose-made aluminium alloy ‘reinforced with functionally graded ceramic particles and fibres to create a lightweight but extremely durable material that can be customised to best serve each section’.
This allows the composition to be optimised for each part of the rotor, team leader Nikhil Gupta said in the statement. ‘The hybrid material allows us to provide reinforcement where additional strength is needed, increase high-temperature performance, and minimize stress at the interfaces between the zones. Together, this should boost rotor life significantly, reducing warranty and replacement costs, and the weight savings will improve the vehicle’s fuel efficiency.’
Gupta and his team expect to come up with a functioning prototype within 12 months
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