Materials that can act as transducers in an actuator for controlling helicopter rotor blade pitch are being assessed at the UK’s University of Salford.

The transducers would respond to magnetic fields, converting the magnetic energy into a physical change and can be compared to piezoelectric materials. However the candidate transducers have a higher energy density and can output more force than piezoelectrics.

Two “magnetorestrictive” materials under study are Terfenol-D and Garfenol. Terfenol-D is an alloy of Terbium, Dysprosium, and Iron and is commercially available.

A magnetic coil is wrapped around the material and the current-induced field generates a dimensional change. Terfenol-D lengthens when encountering such a magnetic field.

“You could use magnetorestrictives to reduce cabin noise if you know the origin of the noise. You can create a vibration out of phase to cancel the noise,” says the University of Salford’s Institute for Materials Research’s magnetic materials and nanostructures’ research group member Xuegen Zhao.

As well as noise reduction, the project’s goal is to develop the magneto elastic transducers for high torque actuation, vibration, electrical energy generation and structural health monitoring.

The assessment is part of the European Union’s €7.56 million ($9 million) three-year Sixth Framework Programme project Magnetoelastic energy systems for even more electric aircraft.

Source: Flight International