Using Neutrons To Design More Efficient Cars and Boats

Using the probing power of neutron beams, Professor Dimitry Sediako at the University of British Columbia is solving industrial challenges in the development of lighter powertrains for automotive and marine vehicles.

Image: There is ample room to improve the energy efficiency of cars, trucks, and boats by reducing how much they weigh. (Shutterstock)

Whether it’s cars on the road or boats on the water, there’s been a pressing need in recent years to make vehicles more energy efficient. “Huge advances are being made in powertrain technology—that is, in the engines and other parts that translate energy from fuel into motion of the vehicle,” says Professor Dimitry Sediako of the University of British Columbia (UBC). “And there is a lot of investment in research to make them even more efficient and lightweight, which reduces energy cost and vehicle emissions.”

Making a vehicle lighter saves on fuel because lighter vehicles need less energy to move. And compared to their heavier counterparts, lighter vehicles are also more easily powered by alternate energy sources, such as hydrogen fuel cells or electric batteries.

But even as alternate energy sources gain popularity, Sediako predicts that gasoline-based technology will continue to be needed. “Internal combustion engines are not outdated or irrelevant,” he notes. “They have much better performance than alternatives, and it may be 30 years or more before alternatives catch up. Even if electric vehicles become commonplace for commuter traffic, internal combustion engines will still be used for higher performance applications.”

“Mercury Marine launched large-scale production of new lightweight gear cases using improved manufacturing methods.”

Prof. Dimitry Sediako joined the UBC School of Engineering from Canadian Nuclear Laboratories in 2017. Sediako is pictured here with a marine gear case, which is an underwater component of an outboard motor.

Since powertrain components, including engines and transmissions, account for much of a vehicle’s weight, they are one focus of the automotive and marine manufacturing industry’s light-weighting research efforts.

In fact, the industry is challenging its materials engineers to not only develop new materials, but also to formulate new ways of processing these materials to ensure they are light enough, strong enough, and inexpensive enough for widespread use in cars and boats. With these criteria in mind, researchers are typically turning to alloys or metal-matrix composites as they seek out better materials for powertrain components.

When developing a new material or processing method for making lightweight parts, it is essential to understand how to maximize their strength and the amount of abuse they can take before failure—which is where Sediako gets involved.

Using leading scientific tools for characterizing materials, Sediako has built a reputation for being able to determine the precise limits of a material’s capabilities. Since arriving at UBC in 2017, he has been directly engaged in projects with individual companies from Canada, the US, and Europe. He has also worked on a number of collaborative research teams with scientists from multiple countries.

Much of this research is proprietary, but one project that is partially in the public domain involves Brunswick Corporation’s Mercury Marine division, which manufactures boat motors using cutting-edge technologies.

“The impact of this research is better fuel efficiency for the boats that use these parts.”

Before collaborating with Sediako, engineers from Mercury Marine were designing a new gear case (i.e., the powertrain component that holds the underwater portion of the motor). Specifically, to minimize weight, they were using a new aluminum alloy (Mercalloy362TM) and an advanced manufacturing technique known as ‘thin wall architecture.’

Casting is a common initial step in forming parts for manufacturing. (Shutterstock)

However, when the company’s engineers were assessing the limits of the gear cases’ performance, the parts developed premature cracking during testing. Premature cracks can be caused by an undesirable microstructure or a high level of stress in the alloy. The methods used to cast an alloy into a desired shape (e.g., that of a gear case) can affect both the microstructure and the stress within the part. For example, the cooling rate during the solidification process is known to affect both the microstructure and the stresses within a component.

To determine the precise cause of the premature cracking in the prototype gear cases, Mercury Marine collaborated with Sediako’s research team at UBC’s Okanagan campus.

Sediako (right) and Stroh (left) prepare for stress measurements on a prototype marine engine gear case.

Sediako has extensive expertise in applying neutron beams to understand what is happening within metals at the molecular level. Neutron beams are the only tool that can be used to non-destructively determine how much stress is hidden deep inside a material. Because neutron beams are non-destructive, they can measure the stresses within the same part both before and after it undergoes manufacturing processes such as heat treatment, which is often used to relieve stress in manufactured components. Neutron beams can also provide information about the material’s microstructure, which is difficult to obtain otherwise.

To learn what was happening within the prototype gear cases, Sediako and two graduate students, Josh Stroh and Alexandra McDougall, accessed neutron beams at the Canadian Neutron Beam Centre to perform a series of stress and microstructure measurements on various Mercalloy362 parts. Combining the neutron beam results with those from other examination methods, Sediako’s team was able to determine the varying microstructures and stress levels in Mercalloy362 parts cast with differing cooling rates, as well as the effect of heat treatment on this material. Some of these results were recently presented at the 2019 conference of The Materials Society (TMS) (doi:10.1007/978-3-030-05864-7_50).

Sediako’s findings provided the critical information that Mercury Marine needed to improve the casting methods used in the production of its prototype gear cases. The company was then able to launch large-scale production of these new lightweight parts using improved manufacturing methods that do not compromise the reliability of its marine engines.

Overall, the impact of this research is better fuel efficiency for the boats that use these parts—and it is just one example of the wider impact Sediako’s team is having on improving the advanced manufacturing techniques for lightweight automotive and marine powertrain components.

This research story was republished with the permission of the Canadian Institute for Neutron Scattering.

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