Research indicates aluminum matrix composites could deliver weight saving for e-motor rotors

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Engineers seeking to improve the efficiency and performance of electric motors could benefit from using aluminum matrix composites (AMCs), according to research from the Innovate UK ‘Make it Lighter with Less’ R&D competition. The project, led by AMC specialist Alvant in collaboration with GE Aviation, Yasa Motors and the National Composites Centre, achieved a 40% rotor weight saving on an axial flux electric motor while increasing the rotor’s power-to-inertia ratio potential. In addition, the number of assembly line parts was reduced, which can result in a shorter assembly time.

As electrification increases, vehicle manufacturers are seeking to optimize motor efficiency maps, for example by improving the efficiency as a function of torque and speed that ultimately determines the energy consumption for vehicles. The industry faces the challenge of identifying ways to improve efficiency and performance, while simplifying manufacturing and overall cost.

Alvant’s proprietary AMCs enable components to be optimized for strength-to-weight and stiffness-to-weight ratio where they are needed, even in a single continuous product. Alvant’s proprietary Advanced Liquid Pressure Forming (ALPF) method can selectively reinforce areas of a component with one of its performance materials in a near net shape manufacturing approach. Alternatively, Alvant’s materials can be applied as discrete inserts into a component, allowing for cost efficiency where an array of similar inserts are the solution.

By adopting AMCs in rotor design, Alvant was able to realize further benefits. In an axial flux electric motor application, suitable for passenger cars, Alvant’s technology can save weight, and the component’s lower mass and reduction in force means engineers may be able to eliminate the number of fixing bolts required, reducing the bill of materials and assembly time.

“Using AMCs, we have been able to attack the weight yet retain the stiffness of the electric rotor, to minimize parasitic mass, improving the power-to-inertia ratio and therefore efficiency and responsiveness,” said Richard Thompson, commercial director of Alvant. “In addition, we can also offer better thermal resistance, up to 300°C, making AMCs a more suitable material than polymer composites for applications such as motors, batteries, energy recovery systems, fans and flywheels.”

In addition to the manufacturing and in-service gains, Alvant’s AMC is more sustainable, thanks to the ability to separate the fibers from the aluminum at the end-of-life stage. “Designers must increasingly factor whole life cost into design and it’s an area where AMCs score well,” added Thompson.

While the Innovate UK/Yasa project focused on a passenger car rotor, Alvant’s own research programs demonstrate the gains to be made by adopting AMCs across multiple high-stress or high-temperature applications in sectors such as aerospace, automotive, defense, consumer goods and sporting equipment.

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About Author


Matt joined UKi Media & Events in 2014 after seven years of living and working in Dubai. He has been a journalist for over a decade and has worked for a wide range of publications, including Rolling Stone, Time Out, iQ and Loaded. After starting out on the automotive team as deputy editor of Engine Technology International, Electric & Hybrid Vehicle Technology International and Transmissions Technology International, he began editing Electric & Hybrid Vehicle Technology International in 2016, and took over as editor of Tire Technology International in 2018.

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