Modeling and power-harvesting applications for magnetic shape memory alloys
NAU Assistant Professor Constantin Ciocanel
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Faculty on leading edge of smart materials research
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W RITING BY :: SYLVIA SOMERVILLE
n Northern Arizona University (NAU) laboratories, teams of researchers are studying ways to make the aerospace, defense, and other industries more energy efficient and less fossil-fuel dependent.
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THE aEROSPaCE & DEFENSE iSSuE
Storing power in composites
One cutting-edge project, involving faculty and students from NAU’s engineering and chemistry departments, focuses on a way to add an electrical-storage component to carbonfiber-based composite materials. These composites, which are lightweight yet strong enough to withstand harsh loading conditions, are being used in high-performance applications in many industries— from medical devices and sporting equipment to aerospace components, such as tails, wings, fuselages, propellers, and heat shields. Now imagine the possibility of enhancing these materials by embedding them with an electrical storage capacity, says Constantin Ciocanel, NAU assistant professor (mechanical engineering). In an aircraft, for example, the sidewall
panels could double as an energystorage device that could be charged when the aircraft is in between f lights or during less energydemanding stages of f light. Having this embedded, electricity-storage capability would reduce the need for batteries or other on-board power-storage devices, leading to a reduction in the aircraft’s weight and, correspondingly, to a decrease in fuel consumption. Built-in backup energy would also enhance the performance of cars, portable electronic devices, wind turbines, and other products. “One’s imagination is the limit on how this can be used,” says Ciocanel. The key to this innovation is a resin being developed by Ciocanel and Cindy Browder, NAU associate professor (organic chemistry). As the resin interfaces with carbon fiber stacks, it allows electricity to be stored without compromising the strength or longevity of the material. (There is no chemical reaction so the composite doesn’t deteriorate.) Plans are under way to make the power-storage composite completely sustainable—built from renewable sources that are biodegradable.
Another groundbreaking NAU project is focused on the modeling of magnetic shape memory alloys (MSMAs) under complex loading conditions. Successfully developing a model will allow engineers to design MSMA-based power harvesters, actuators, or sensors. This collaborative project within NAU’s mechanical engineering department involves both theoretical and practical breakthroughs. “Current models are excessively simple. They restrict loading to one direction,” says Heidi Feigenbaum, NAU assistant professor (mechanical engineering). “Our model is much more complex.” MSMAs exhibit up to 6 percent strain when subjected to a magnetic field and no mechanical stress. The strain or growth of the material is accompanied by a change in magnetization, which can be harnessed into voltage by placing a pick-up coil around the specimen. Also, because the strain in MSMAs is very fast (unlike in regular shape memory alloys), the material can be used for actuation or sensing applications. Although power-harvesting research is currently being conducted in the laboratory, the process can easily take place in nature. “For example, if a MSMA power harvester were to be placed in a tree in a forest and moving branches pushed against it, the alloy could deform, and the pickup coil could harvest the released energy,” Ciocanel explains. “If a humidity monitor were attached to the power harvester, you would not have to use batteries to power the sensor. You would use wind energy instead.” These are just two examples of some of the innovative, far-reaching projects being developed by NAU faculty members and the students who work with them. Each year two graduate students and four or five undergraduate students have an opportunity to work with Ciocanel and his research partners—invaluable hands-on, realworld experience that has contributed to the increasing number of mechanical engineering majors at NAU. Sylvia Somerville is a writer and editor in Northern Arizona University’s research division.
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